Biology Today - January 2016.pdf

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Vol. XVIII

No. 1

January 2016

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Unitwise Practice Paper (Unit V)

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17 AIIMS Special (XI & XII)

Assertion & Reason : Morphology of Flowering Plants, Principles of Inheritance and Variation

19 Glance Around 20 Practice Paper-PMT 31 PMT Foundation (XII) 43 High Yield Facts-Botany

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MT BIOLOGY

TODAY | january ‘16

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UNIT V Organisms and Populations

6

Ecosystem Biodiversity and Conservation Environmental Issues

GENERAL INSTRUCTIONS (i) All questions are compulsory. (ii) This question paper consists of five Sections A, B, C, D and E. Section A contains 5 questions of one mark each. Section B contains 5 questions of two marks each, Section C contains 12 questions of three marks each. Section D contains 1 question of VBQ type with four marks and Section E contains 3 questions of five marks each. (iii) There is no overall choice. However, an internal choice has been provided in one question of 2 marks, one question of 3 marks and all the three questions of 5 marks weightage. A student has to attempt only one of the alternatives in such questions. (iv) Wherever necessary, the diagrams drawn should be neat and properly labelled.

SECTION - A 1. Which type of biotic interaction is mainly responsible for the biological control method of managing the pests? 2. A tadpole and an adult frog occupy different ecological niches. Give reason. 3. What is the percentage of photosynthetically active radiation (PAR) in the incident solar radiation? 4. Mention the broadly utilitarian argument for the conservation of biodiversity. 5. Why species richness increases with increased study area? SECTION - B 6. Give an example of mutualistic association in which the organisms involved are commercially exploited in agriculture. OR How is primary productivity affected by sunlight? Give example. 7. Cryopreservation help in the conservation of biodiversity. Explain. 8. What does the given age pyramid signify about the status of a population? The bar at the base represents prereproductive individuals.

........................ ....................... ........................ ....................... ........................ ....................... 8

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9. What do you mean by reservoir pool in terms of nutrient cycling? What is its function? 10. At a particular segment of a river near a sugar factory, the BOD is much higher than the normal level. What is it indicative of? What will happen to the living organisms in this part of the river? SECTION - C 11. We have many threads which weave the different areas of biological information into a unifying principle. Ecology is one such thread which gives us a holistic perspective to biology. Justify the above statement with suitable explanation. 12. How are the animals living in arid or desert areas adapted to survive in conditions of water scarcity? Explain with suitable example. 13. How do organisms cope with stressful external environmental conditions which are localised or of short duration? OR Name the pioneer community and climax community in a xerosere. How does the pioneer species help in establishing next type of vegetation in xerosere? 14. (a) In a population, per capita birth rate is 0.025 and per capita death rate is 0.008 during a unit time period. What is the value of intrinsic rate of natural increase, 'r' for the population? (b) Define resource partitioning.

15. Study the given figures showing two regions X and Y containing different numbers and types of species, and answer the accompanying question. Site 1

Site 2

Site 3

Site 4

Region X

Region Y

Which out of the two regions shows higher beta diversity and why? 16. Give diagrammatic representation of carbon cycle. 17. Explain the odd shape of the given pyramid of numbers. Buzzard Black birds Caterpillars Oak tree

18. Among plants and animals, which group exhibits greater species diversity? Support your answer with explanation. 19. (a) What is meant by the term 'hotspot' in biodiversity? Mention two criteria used for determining a hotspot. Name any one hotspot of India. (b) Exotic species often become invasive and drive away the native species. Give an example to justify this statement. 20. Explain any three measures to control vehicular air pollution in Indian cities.

in an industry. (a) Which values have been shown by Mayank in above situation? (b) How does an electrostatic precipitator work? (c) State the consequences if the electrostatic precipitator of a factory or a thermal power plant stops functioning? SECTION - E 24. (a) How are herbs and shrubs able to survive under the shadow of big canopied trees in thick forests? (b) A cuckoo bird lays her eggs in the crow's nest. How do you describe this interaction between the cuckoo and the crow? (c) What are osmoconformers? OR Differentiate between : (a) Primary succession and secondary succession. (b) Primary productivity and secondary productivity. 25. What is decomposition? Describe the different steps involved in the process of decomposition in an ecosystem. OR (a) With the help of a graph explain the effect of sewage discharge in river and recovery of the same after some distance. (b) Mention the four main greenhouse gases along with their percentage contribution towards greenhouse effect. 26. Explain species area relationship of biodiversity with the help of suitable graph. OR Winner : Ankita Singh, Ranchi

SOLUTIONS TO NOVEMBER 2015 CROSSWORD 1

A N

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SECTION - D 23. Mayank and Devansh are partners in a factory. After a few months of the establishment of the factory, the electrostatic precipitator (ESP) stopped functioning and needed to be replaced. Mayank wanted to replace it but Devansh said that it had no impact on the productivity and income, and therefore they should not waste money in buying a new electrostatic precipitator. Mayank convinced him by telling him about the advantages and disadvantages of using ESP 10

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21. Why does biomagnification occur with toxic substances such as heavy metals, persistent pesticides etc? 22. What are hybrid vehicles? Enlist advantages and disadvantages of using hybrid vehicles.

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(a) Explain, by giving examples, any three different ways by which population density can be measured. (b) Differentiate between interspecific competition and intraspecific competition. SOLUTIONS 1. Predation (between the pest and biocontrol agent) is the biotic interaction which is mainly responsible for the biological control method of managing the pests. 2. A tadpole and an adult frog occupy different ecological niches because the former is herbivorous and aquatic while the later is carnivorous and amphibian. 3. The percentage of photosynthetically active radiation (PAR) in the incident solar radiation is less than 50%. 4. The broadly utilitarian argument says that biodiversity is fundamental to ecosystem services that nature provides like pollination, microbial waste treatment, biological pest control etc. 5. Species richness depends upon habitat variation. Larger study area includes larger variety of habitats, thus shows greater species richness. 6. Mutualistic association between nitrogen fixing cyanobacterium Anabaena and water fern Azolla is of great agricultural importance in increasing rice production. It increases nitrogen content of soil. OR Primary productivity increases with an increase in availability of sunlight due to increased photosynthetic rate. For example, productivity in aquatic ecosystems is lesser than that in terrestrial ecosystems. It is because in aquatic ecosystems, availability of light decreases with increasing water depth. 7. Cryopreservation refers to the storage of living cells, tissues, embryos, gametes, etc. at –196°C (liquid nitrogen). The cryopreserved material is revived through special technique when required. In order to prevent extinction, endangered microorganisms or the propagules of other organisms are being cryopreserved so that they can be revived when required. Thus, cryopreservation is an important ex situ method of conservation of biodiversity. 8. Given is a bell-shaped age pyramid which signifies that the population is stable. Such age pyramid is formed when the number of pre-reproductive and reproductive individuals is almost equal and the post-reproductive individuals are comparatively fewer. It implies that the population is neither decreasing nor increasing, instead is maintained at a stable level. 12

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9. Reservoir pool is the reservoir of biogenetic nutrients from which the latter are slowly transferred to cycling pool, e.g., reservoir pool of phosphates are rocks. The function of reservoir pool is to meet deficiency of nutrient which occurs due to differences in the rate of influx and efflux. 10. A higher BOD indicates that the particular segment of the river is highly polluted. As a result, there will be sharp decline in the dissolved oxygen content in this part. It will result in mortality of fish and other aquatic organisms. 11. Ecology is defined as the study of inter-relationships between living organisms and their environment. The two main branches of ecology are – autecology and synecology. Autecology studies inter-relationship of the organisms of a single species with biotic or abiotic environment. Synecology studies inter-relationship of different groups of the living organisms, such as populations, biotic communities and their environment which are associated together as a unit. Thus it connects all organisms either plants or animals, aquatic or terrestrial together and analyses their influences on one another, their co-existence, sustainance of life on earth etc. Thus, ecology is basically concerned with different levels of ecological hierarchy or ecological organisation and works as the thread which gives us a holistic perspective to biology. 12. Animals living in the conditions of water scarcity show two types of adaptations—reducing water loss from the body and conserving water in the body. For example, desert rat who seldom gets to drink water due to scarcity has a thick coat to minimise evaporative desiccation. The animal seldom comes out of its comparatively humid and cool burrow during the day time. 90% of its water requirement is met from metabolic water (water produced by respiratory breakdown of fats) while 10% is got from food. Loss of water is minimised by producing nearly solid urine and faeces. 13. Living organisms cope with stressful condition by any of the following methods: (i) Migration : The organism can migrate temporarily from the unfavourable habitat to more favourable area and return when unfavourable period is over e.g., Siberian birds migrates from Siberia to other parts in every winter. (ii) Hibernation : The animal spends cold period in an inactive stage and resumes activity in summers. e.g., polar bears undergo hibernation during winter season to escape extreme cold.

(iii) Aestivation : Animal spend dry hot period in an inactive stage and resumes activity in favourable conditions. e.g., snails and fish. (iv) Diapause : Many insects and other invertebrates undergo diapause in which development or growth is suspended and metabolism is greatly reduced. In some long lived species adults may undergo diapause while in some the egg is the diapausal stage. It enables the animal to survive unfavourable environmental conditions. OR The pioneer species on a bare rock are usually lichens. They secrete acids to dissolve rock, helping in weathering and soil formation. These later, pave way to some very small plants like bryophytes, which are able to take hold in the small amount of soil formed by lichens' action. The climax community that will ultimately get established is forest. 14. (a) Intrinsic rate of natural increase, r = Per capita birth rate – Per capita death rate = 0.025 – 0.008 = 0.017 (b) When two or more species divide a niche to avoid competition for resources, it is called resource partitioning. Organisms with similar requirements may evolve to reproduce at different times of the year, feed at different times of the day or night, or use different parts of the habitat like different areas of a forest or different depths of a lake. 15. Region Y has higher Beta (b) diversity than region X. It is because Beta diversity measures the amount of change between two sites in a region and there is a higher turn over of species among the sites 2 and 4 in region Y. 16. Refer to answer 13, page no. 388, `MTG Excel in Biology’. 17. Given diagram represents the spindle-shaped pyramid of numbers in a forest ecosystem, showing 4 different trophic levels. The number of producers (oak trees) and the number of top consumers (buzzards) is small. This can be explained as follows: A single large oak tree supports hundreds of caterpillars, so the number of organisms increases from first to second trophic levels. However, a few black birds can feed on these caterpillars (number in tens) and even fewer buzzards (birds of prey) can feed on these black birds. So the number of organisms decreases at the third and fourth trophic levels. 18. Refer to answer 6, page no. 405, `MTG Excel in Biology’. 19. (a) Hotspots are those regions of rich biodiversity which have been declared sensitive due to direct or indirect 14

MT BIOLOGY

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interference of human activities. The two main criteria for determining a hotspot are: (i) Number of endemic species (ii) Degree of threat in terms of habitat loss. One of the hotspots of India is Western Ghats. (b) Water hyacinth (Eicchornia) had been introduced in Indian waters due to its aesthetic values. However, it spread rapidly in water bodies by vegetative propagation i.e., became invasive. Its rapid growth clogged water bodies and resulted in deaths of several native aquatic plants and animals. Thus, it drove away the native species. 20. Three measures to control vehicular air-pollution in Indian cities are : – Use of CNG as fuel in the vehicles because it burns more efficiently and little of it is left unburnt. It is also cheaper. – Use of unleaded petrol in the vehicles. – Use of catalytic converter in the vehicles as it reduces emission of poisonous gases. 21. Biomagnification occurs with toxic substances because these toxic substances are generally lipophilic and get deposited in the tissues of organism. These toxic substances accumulated by an organism cannot be metabolised or excreted, and are passed on to the next higher trophic level where they get accumulated and magnify in quantity as the higher trophic level organism consumes multiple organisms of the lower trophic level. Two such substances are mercury and DDT.

READERS’ REVIEWS You are doing a great job. I just love your “Biology Today”. Thanks for such a magazine. Abhishek Gaurav Biology Today is an immensely helpful magazine and I thoroughly enjoy reading it. The question papers are very helpful and has helped me to clear many of my previous doubts. With so much competition all around, Biology Today has proved out to be a real life saver. Feeling privileged to be one of the readers of this amazing magazine. Joydeep Saha Biology Today is the best magazine for Medical Entrance Exams. Suman Das MTG magazines and books are good enough to give a new approach to learning and get new idea about it. Abdul Rehman

22. Hybrid vehicles are the vehicles which employ more than one type of energy/fuel source, such as traditional internal combustion engine + an electric motor, e.g., diesel-electric trains use diesel engines and electricity from overhead line. Advantages : (i) Hybrid vehicles are more fuel efficient. (ii) Hybrid vehicles cause less pollution. Disadvantages : Hybrid vehicles prove to be costlier as they employ two different types of fuel sources. 23. (a) Mayank shows responsibility and concern towards environment and health of other organisms. (b) Refer to answer 6(ii), page no. 429, `MTG Excel in Biology’. (c) Refer to answer 8(i), page no. 430, `MTG Excel in Biology’. 24. (a) Herbs and shrubs survive under the shadow of big canopied trees in forests as they are perfect shade tolerant plants which show better growth in lower level of light intensity. They grow in a manner, that they are arranged in different strata according to their shade tolerance.

(b) CO2 – 60%, CH4 – 20%, CFCs – 14% and N2O – 6% 26. Refer to answer 15, page no. 410, `MTG Excel in Biology’. OR (a) Three different ways to measure population density are as follows: (i) It can be measured as numerical density (number of individuals per unit area or volume), e.g., number of Siberian cranes at Bharatpur wetlands in any year. (ii) It can be measured as biomass density (biomass per unit area or volume), e.g., a dense laboratory culture of bacteria in a Petri dish. (iii) It can be measured as relative density, e.g., the number of fish caught per trap can give a relative measure of the population density of the fish in water body. (b) Differences between intraspecific and interspecific competition are as follows:

(b) Refer to answer 8, page no. 366, `MTG Excel in Biology’.

Intraspecific competition

Interspecific competition

(c) Osmoconformers are those organisms which cannot maintain osmolarity of their body fluids constant and it varies according to their surrounding medium. OR

(i)

It is competition among The competition is individuals of the same amongst the members species. of different species.

(a) Refer to answer 11, page no. 393, `MTG Excel in Biology’.

(ii)

The competition is for all The competition is for one the requirements. or a few requirements.

(b) Refer to answer 9(f), page no. 387, `MTG Excel in Biology’. 25. Refer to answer 3, page no. 385, `MTG Excel in Biology’. OR

Concentration

(a) The graph showing effect of sewage discharge on a water body is as follows: Dissolved oxygen

(iii) The competing indivi- The competing individuals have similar duals have different adaptations. adaptations. (iv) It is more severe due It is less severe as the to similar needs and similar needs are a few adaptations. and the adaptations are different. 

BOD

Sewage discharge

Direction of flow of river

Due to discharge of sewage into the river, micro-organisms present in the river get involved in biodegradation of added organic matter and in the process consume a lot of dissolved oxygen present in river. Due to this, biochemical oxygen demand (BOD) of the river increases. As sewage is decomposed gradually, there occurs a rise in dissolved oxygen downstream and decrease in the BOD of the river water.

NOVEMBER 2015 1. VIROIDS

2. GINKGO

3. EPHEDRINE

4. SANGUIVORES

5. CRYPSIS

6. GEMMULES

7. EPIMORPHOSIS

8. NEELAKURANJI

9. MIRACIDIUM

10. SPOROPOLLENIN Winners : Raya Ghosh, Akansha Deshmukh(Chattisgarh), Raja Faizan Nabi(Srinagar)

MT BIOLOGY

TODAY | JANUARY ‘16

15

BIO -GRAM

ELISA An ELISA (Enzyme Linked Immuno Sorbent Assay) test is a method that uses components of the immune system and chemicals to detect immune responses in the body (e.g., to infectious microbes). It determines if certain substance, such as specific cytokine or antigen is present within a sample or not. ELISA is important for early diagnosis of diseases. Direct ELISA, the simplest type of ELISA is explained here. Sample coated well

Sample

Microtiter plate or ELISA plate

Antigens

Buffered samples that may contain the antigen to be tested for, are added to each well of a microtiter plate, where the samples are given time to adhere to the plastic through charge interactions. The sample in each well is immobilised on the solid support i.e., microtiter plate (usually made up of polystyrene); either non–specifically (via adsorption to the surface) or specifically (via capture by another antibody specific to the same antigen, in a “sandwich” ELISA).

Wells containing different samples

After antigen immobilisation, the detection antibody (primary antibody) is added, forming a complex with the antigen. The plate is incubated at room temperature and is typically washed with a mild detergent solution (or deionised water) multiple times, to remove any proteins or antibodies that are non–specifically bound.

Primary antibody specific to antigen

Primary antibody binds to antigen

Enzyme E

E

E

Secondary antibody Primary antibody Antigen

A substrate called chromogen is added that will change colour only when enzyme is present. If patient’s sample had the antigen to which the enzyme linked antibodies bound (through the primary antibody) then colour change would be seen. After adding the chromogen, plate is incubated for 30 mins.

A second set of antibodies specific for pathogen and conjugated with an enzyme is added to the plate, which attaches with the primary antibody-antigen complex. Then it is incubated at room temperature and plate is washed for the second time to remove unbound secondary antibodies.

Chromogenic substrate S

E

E

S

Enzyme linked secondary antibody

E S

Changed colour indicates presence of antigen

Dilute acid stop solution is added and the ELISA plate is read at 450 nm. The higher the concentration of the primary antibody present in the serum, the stronger is the colour change. Often, a spectrometer is used to give quantitative values for colour strength. 16

MT BIOLOGY

TODAY | january ‘16

PRACTICE QUESTIONS ON

Assertion & Reason

 

MOrphOLOGY Of fLOwerInG pLAnTs prIncIpLes Of InherITAnce AnD vArIATIOn

Direction : In the following questions, a statement of assertion is followed by a statement of reason. Mark the correct choice as : (a) If both assertion and reason are true and reason is the correct explanation of assertion. (b) If both assertion and reason are true but reason is not the correct explanation of assertion. (c) If assertion is true but reason is false. (d) If both assertion and reason are false. MOrphOLOGY Of fLOwerInG pLAnTs 1. Assertion : root cap is present at the apex of the root. Reason : root cap protects the root meristem as it penetrates the hard soil. 2. Assertion : Banyan tree has prop roots. Reason : Prop roots help the plant to get oxygen for respiration. 3. Assertion : Leaves of dicot plants generally possess parallel venation. Reason : Veinlets are conspicuous in dicots. 4. Assertion : In Artabotrys the stem is modified into stiff curved thorns or hooks. Reason : The hooks help the plant in climbing. 5. Assertion : roots are endogenous in origin. Reason : root branches develop from the interior usually pericycle of the parent root. 6. Assertion : In Mimosa pudica, the leaf base is swollen. Reason : Pulvinus is responsible for sleep and shock movements in Mimosa leaves. 7. Assertion : The opposite type of phyllotaxy is the arrangement of leaves in which two leaves are borne on the opposite sides of a single node. Reason : The opposite type of phyllotaxy is seen in China rose and oleander.

8. Assertion : The racemose type of inflorescence has indefinite growth. Reason : In racemose inflorescence, the peduncle continues to grow forming new bracts and flowers in succession. 9. Assertion : Hypanthodium is found in Ficus carica. Reason : In hypanthodium, receptacle is open from above. 10. Assertion : Mustard flower has radial symmetry. Reason : Mustard bears actinomorphic flowers. 11. Assertion : Caryophyllaceous corolla is found in carnation. Reason : Caryophyllaceous corolla has five or more sessile or shortly clawed petals bent horizontally like a saucer. 12. Assertion : In imbricate aestivation, one margin of a petal overlaps the margin of an adjacent petal and the other margin being overlapped by margin of adjacent petal. Reason : Imbricate aestivation is found in China rose. 13. Assertion : a true fruit is a ripened ovary which develops after fertilisation under the influence of ripening ovules. Reason : Eucarp consists of a pericarp formed from the walls of ovary and seeds formed from ovules. 14. Assertion : The outermost covering of a dicotyledonous seed is the seed coat. Reason : The seed coat has two layers outer testa and inner tegmen. 15. Assertion : The fruit of apple is called a pome. Reason : Pome develops from the fleshy thalamus of multicarpellary, syncarpous, inferior ovary. prIncIpLes Of InherITAnce AnD vArIATIOn 16. Assertion : Genes are called the units of inheritance. Reason : Genes contain the information required to express a particular trait in an organism. MT BIOLOGY

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17

17. Assertion : In monohybrid cross, in F2 generation, two traits of character are expressed in the proportion of 3 : 1. Reason : 3 : 1 ratio of F2 generation is due to segregation of factors present in F1 plants during gamete formation. 18. Assertion : The F 1 generation of andalusian fowls comprises of blue coloured fowls. Reason : Blue colour is due to epistatic suppression of black colour in one of parental fowls by alleles of white colour. 19. Assertion : Mendel used true-breeding lines for conducting experiments on genetic studies. Reason : True breeding lines show the stable trait inheritance and expression for several generations. 20. Assertion : aBO blood group system provides a good example of incomplete dominance. Reason : In aBO blood group system, none of the two contrasting alleles is dominant. 21. Assertion : F2 progeny obtained by cross-breeding of white coat coloured short horned cattle with red coat colour, shows ratio of 1 : 2 : 1. Reason : In short horned cattle, roan colour is produced due to juxtaposition of small patches of red and white colour. 22. Assertion : Chromosomes have a definite role in the development of an individual. Reason : In many organisms, sex of an individual is determined by specific chromosomes, called sex chromosomes. 23. Assertion : Some insects have XO type of sex determination mechanism. Reason : Insect’s eggs bear one X-chromosome alongwith autosomal chromosomes. 24. Assertion : Xy type of sex determination mechanism is an example of male heterogamety. Reason : In birds, male heterogamety is seen as males produce two different types of gametes. 25. Assertion : Sickle-cell anaemia results from point mutation. Reason : In sickle-cell anaemia, haemoglobin molecule undergoes polymerisation under low oxygen tension causing the change in shape of rBCs. 26. Assertion : Haemophilia is a sex-linked recessive disease in which heterozygous female transmits the disease to 50% of her male progeny. Reason : Haemophilia is due to presence of recessive sex linked gene present on y chromosome. 27. Assertion : accumulation of phenyl pyruvic acid in brain results in mental retardation in case of phenylketonuria. Reason : The affected individual lacks enzyme for the conversion of phenylalanine into tyrosine. 18

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28. Assertion : Down’s syndrome is a genetic disorder caused due to the presence of an additional copy of X-chromosome. Reason : Both X chromosomes pass into single egg due to non disjunction during oogenesis. 29. Assertion : Variety of coat colour in mice is result of dominant epistasis. Reason : In dominant epistasis, a dominant gene at one locus enhances the expression of another gene at a different locus. 30. Assertion : Monogenes produce continuous variations in the expression of traits. Reason : Monogenic inheritance controls quantitative trait.

ANSWER 1. 6. 11. 16. 21. 26.

(a) (b) (c) (a) (b) (c)

2. 7. 12. 17. 22. 27.

(c) (c) (d) (a) (b) (a)

3. 8. 13. 18. 23. 28.

(b) (a) (b) (c) (b) (d)

KEY 4. 9. 14. 19. 24. 29.

(b) (c) (b) (a) (c) (d)

5. 10. 15. 20. 25. 30.

(a) (a) (b) (d) (b) (d)



9.

10.

11.

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he questionnaire contains multiple choice questions based on current affairs and recent developments worldwide. Various facts are presented in question form to enable the students to develop knowledge as well as to test their general awareness skills and equip them with all essentials to crack various PMTs (AIIMS, etc.) This will also help them to excel in other competitive exams like Banking and various Government recruitment exams.

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Who among the following was recently suspended by International Cricket Council (ICC) for illegal bowling action? (a) Saeed ajmal (b) Kane Williamson (c) Sunil narine (d) Sachithra Senanayake World aIDS Day was celebrated on ............. 2015. (a) 25th november (b) 1st november (c) 25th December (d) 1st December _________ was elected as the president of the West african country Burkina Faso. (a) roch Marc Christian Kabore (b) Zephirin Diabre (c) Tahirou Barry (d) Michel Kafando Which of the following was awarded Golden Peacock award for the Best Film at 46th International Film Festival of India? (a) The Measure of a Man (b) Embrace of the Serpent (c) Sealed Cargo (d) Eisenstein in Guanajuato robert Lewandowski, a polish footballer was recently awarded with four Guinness World record certificates for scoring ____. (a) five goals in eight minutes fifty nine seconds (b) four goals in eight minutes twenty seconds (c) three goals in ten minutes ten seconds (d) seven goals in ten minutes Which of the following currency was recently approved as Elite reserve Currency by International Monetary Fund (IMF)? (a) Indian rupee (b) uS Dollar (c) British Pound (d) Chinese yuan In which state of India, the coal miners recently switch to turmeric farming after the ban on coal mining and transportation of coal by national Green Tribunal (nGT) in april 2014? (a) assam (b) Meghalaya (c) nagaland (d) arunachal Pradesh according to World’s 20 Most Generous People list released recently by Wealth–X and Business insider, ______ ranks fourth in the world. (a) Warren Buffett, CEO of Berkshire Hathaway

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17.

18.

(b) Gordon Moore, Co-founder of Intel (c) azim Premji, Chairman of Wipro (d) Mark Zuckerberg, Founder of Facebook Who among the following won Macau Open Grand Prix Gold Women’s Singles title for 3rd consecutive time? (a) PV Sindhu (b) Minatsu Mitani (c) Saina nehwal (d) Carolina Marin On 27th november 2015, LrSaM missile co-developed by India and Israel was successfully tested from an Israeli navel Platform. The missile is a/an ________. (a) air-to-surface missile (b) surface-to-surface missile (c) surface-to-air missile (d) air-to-air missile Garden reach Shipbuilders and Engineers Limited (GrSE) handed the second anti-Submarine Warfare Corvette ‘Kadmatt’ to Indian navy. Which of the following statement(s) is/are correct regarding the highlights of this report? I. The warship was handed over by rear admiral (retd.) a. K. Verma, Chairman and MD of GrSE to the Commanding Officer of the ship Mahesh C. Moudgil. II. The ship is capable to fight in nuclear, biological and chemical warfare environments. (a) I only (b) II only (c) Both I and II (d) neither I nor II Who has been recently appointed as Head of retail Banking in the Mashreq’s Banking Group? (a) Som Subroto (b) Farhad Irani (c) arundhati Bhattacharya (d) naina Lal Kidwai The Mayyazhi Mahotsavam 2015 was held in which union Territory of India? (a) national Capital Territory of Delhi (b) Chandigarh (c) Daman and Diu (d) Puducherry The first historic day-night Test match played at adelaide Oval was played between which of the following two countries? (a) australia and South africa (b) India and South africa (c) new Zealand and Sri Lanka (d) australia and new Zealand Who among the following recently became the WBa (Super), IBF, WBO, IBO and The ring unified heavyweight champion? (a) Wladimir Klitschko (b) Tyson Fury (c) rico Verhoeven (d) Benjamin adegbuyi Which of the following countries recently allowed women to contest municipal elections? (a) Libya (b) Sudan (c) Saudi arabia (d) Serbia Which of the following countries is building world’s largest animal cloning factory? (a) united States of america (b) China (c) Japan (d) India Which among the following countries recently launched its first commercial satellite? (a) China (b) South Korea (c) India (d) Japan

ANSWER 1. 6. 11. 16.

(c) (d) (c) (c)

2. 7. 12. 17.

(d) (b) (a) (b)

3. 8. 13. 18. MT BIOLOGY

(a) (c) (d) (d)

KEY 4. 9. 14.

(b) (a) (d)

TODAY | January ‘16

5. (a) 10. (c) 15. (b)  19

PRACTICE PAPER

CLASS XI & XII

SInGLe OpTIOn COrreCT This paper contains 180 multiple choice questions. Each question has four choices (a), (b), (c) and (d), out of which ONLY ONE is correct. (Mark only One Choice). Negative Marking (–1)

Marks : 180 × 4 = 720

CLASS XI 1. Which of the following is a correct statement? (a) Methanomonas bacteria, present in gut of ruminant animals, are obligate anaerobic, which are used in production of biogas. (b) Vast majority of bacteria are autotrophic and a few are heterotrophic. (c) Bacterial structure is simple, they are very complex in behaviour and show the most extensive metabolic diversity. (d) Mycoplasma are facultative anaerobic.

4. Eight bacteria kept in cup divide repeatedly and produce 64 bacteria in 2 hours. Find the time consumed in binary fission. (a) 15 minutes (b) 20 minutes (c) 40 minutes (d) 30 minutes

2. ‘Citrus canker’ is a well known disease of citrus plants, characterised by development of holes in their leaves due to necrosis caused by (a) Pseudomonas citri (b) Penicillium citri (c) Trichoderma citri (d) Xanthomonas citri.

5. How many of the following statements are true? (i) Building block of fungal body is mycelium. (ii) Lichens exchange gases through ‘cephalodium’. (iii) Lichens and mosses are air pollution indicators. (iv) Oospores, zoospores and conidia are asexual spores of fungi. (v) Trichonympha found in the intestine of termites help in their nutrition. (a) 2 (b) 4 (c) 3 (d) 1

3. Which of the following statements are true w.r.t. bacteria? (i) Typical bacteria are 1-2 mm in size. (ii) Glycocalyx differs in composition and thickness among different bacteria. (iii) Fimbriae are elongated tubular structures formed of special protein, help in attachment of bacteria to host cell. (iv) Mesosome of bacteria is formed of extensions of plasma membrane in the cell anterior, in the form of vesicles, tubules and lamellae helping in anaerobic respiration. (v) Polysome of bacteria is formed of one r-RNA attached to many ribosomes. (a) (i) and (ii) (b) (i) and (iv) (c) (ii), (iii) and (iv) (d) All except (ii)

6. Which of the following statements are correct? (i) Dikaryon in higher fungi is n + n nuclei containing, where two nuclei are commonly different in genetic makeup. (ii) Fungus growing on dung is coprophilous, where as growing on bark is corticolous. (iii) Disease of fungus producing ‘sooty mass’ of spores is called smut, which is caused by Puccinia. (iv) Alternaria, Colletotrichum and Trichoderma belong to Class Deuteromycetes. (v) Morchella is an edible mushroom of Class Basidiomycetes. (a) (i), (ii) and (iv) (b) (ii), (iv) and (v) (c) (i), (ii), (iv) and (v) (d) All the five statements are true.

Contributed by : Harpal Singh, Harpal's Biology Classes, Chandigarh, 09781124215

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7. Which of the following are incorrect matches? (i) Bracket fungi – Harmful to our timber resource (ii) Neurospora – Used extensively in biochemical and genetic research (iii) Lysergic Acid Diethyl amide – Hallucinogenic and derived from Claviceps purpurea (iv) Albugo candida – Belongs to Class Phycomycetes (v) Conidiospores – Deuteromycetes and Ascomycetes (a) (i) and (iii) (b) (ii), (iii) and (v) (c) (iii) and (v) (d) None of these 8. How many of the following fungi are members of Basidiomycetes? Agaricus, Aspergillus, Alternaria, Puff balls, Claviceps, Ustilago, Puccinia, Albugo, Trichoderma, Edible Morel (a) 5 (c) 6

(b) 4 (d) 7

9. Which of the following criteria used for classification of Fungi into its classes? (a) Mode of spore formation (b) Morphology of mycelium (c) Fruiting bodies (d) All of these 10. Which of the following is true of its label from 1 to 4?

(a) 4 – ‘Gills’ help in exchange of gases. (b) 3 – Annulus, outgrowth of pileus for assisting in spore dispersal. (c) 2 – Stipe edible part, rich in protein and formed of secondary mycelium. (d) 1 – Primary mycelium produced by germination of teleutospore. 11. Bacteria differ from cyanobacteria by which of the following features? (i) Absence of flagella and fimbriae. (ii) dsDNA without attached histones. (iii) Anoxygenic photosynthesis. (iv) Stored food as glycogen. (v) Absence of N2 fixing cells like heterocyst. (a) (i), (iii) and (iv) (b) (ii), (iv) and (v) (c) (iii), (iv) and (v) (d) (i), (iii), (iv) and (v) 22

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12. Which of the following is a correct one? (a) NH3 ¾X¾ ® NO2 ¾Y¾ ®NO3, where X = Nitrobacter, Y = Nitrosomonas. (b) Pseudomonas and Thiobacillus → Denitrifying bacteria. (c) Gram –ve bacteria susceptible to antibiotics. (d) Frankia – Fixes nitrogen in leguminous root nodules. 13. Which of the following environmental conditions essential for the optimum growth of Rhizopus on a stale bread piece? (i) Darkness (ii) Relative humidity 95% (iii) Well lighted place (iv) Temperature 5°C (v) Relative humidity about 10% (vi) Temperature of about 25°C (a) (i), (ii) and (vi) (b) (ii), (iii) and (vi) (c) (i), (v) and (vi) (d) (i), (iv) and (v) 14. Which is correct w.r.t. cell wall of bacteria and fungi? (a) In both, it is highly selective for absorption. (b) Both contain mucopeptide. (c) Both contain abundant cellulose. (d) Both contain NAG. 15. Read carefully the table and fill up the blanks: Classes

Major Pigments

Stored Food

Cell Wall

Flagellar Number & Position of Insertions

Chlorophyceae

A

Starch

Celluose

2-8, equal, apical

Phaeophyceae

Chlorophyll-a and c fucoxanthin

Mannitol, laminarin

Rhodophyceae

Chlorophyll-a and d phycoerythrin

B

C

Cellulose

2, unequal, lateral

D

A, B, C and D in the above table refer to (a) A-chlorophyll-a and d; B-Starch and Laminarin; C-Cellulose; D-2-10 equal apical (b) A-Chlorophyll-a and c; B-Mannitol and starch; C-Cellulose and algin; D-2-8 equal lateral (c) A-Chlorophyll-a and b; B-Floridean starch; C-Cellulose and algin; D-Not present (d) A-Chlorophyll-a and b; B-Mannitol and floridean C-Cellulose; starch; D-Not present 16. In algae, vegetative reproduction mainly takes place by (a) budding (b) akinetes only (c) fragmentation (d) heterocyst.

17. How many of the following statements are true? (i) Volvox and Fucus show oogamy. (ii) Agar is commercially obtained from Gelidium and Gracillaria. (iii) Gametophyte is parasite on sporophyte in Sphagnum. (iv) Funaria is monoecious and Marchantia is dioecious. (v) Source of SCP are Spirullina and Chlorella. (a) 4 (b) 3 (c) 5 (d) 2 18. Group of sporangia on a sporophyll is known as (a) inducium (b) prothallus (c) sorus (d) strobilus. 19. Assume that a fern sporophyte has two fertile leaves. Each containing 10 fertile pinnae. Each fertile pinna contains 4 sori. If each sorus contains 5 sporangia and each sporangium contains 6 spore mother cells, then the total number of spores produced will be (a) 9600 (b) 2400 (c) 4800 (d) 19,200. 20. Which of the following statements is false? (a) Floridean starch is a stored food in red algae which is very much similar to amylose and glycogen in structure. (b) Sphagnum is monoecious and autoecious, whereas, Marchantia is dioecious. (c) ‘Horse tail plants’ belong to Class Sphenopsida and contain scale leaves and photosynthetic stem. (d) Polysiphonia and bryophytes show haplodiplontic life cycle. 21. Juvenile gametophyte, the protonema, is found in (a) some mosses and vascular cryptogams (b) all bryophytes (c) all mosses and some liverworts (d) mosses. 22. How many of the following structures are haploid? Zygote of fern, Oosphere of liverwort, Gemma cell in Marchantia, Prothallus of fern, Sperm mother cell of Funaria, Leaf cell of a moss (a) 5

(b) 4

(c) 6

(d) 3

23. Heterospory originated in (a) seed bearing primitive dicots (b) Sphagnum (c) Selaginella (d) Adiantum. 24. Assumed number of chromosomes in endosperm of a gymnosperm is 16. Find which of the following is a correct match, w.r.t. organs and chromosome numbers. (a) Leaf = 32 (b) Pollens = 16 (c) MMC = 32 (d) All of these.

25. Which of the following is the most distinguishing feature of bryophytes? (a) Autotrophic gametophyte parasitised by sporogonium. (b) Mostly homosporous, but, a few heterosporus. (c) 1st cell in the life of sporophyte is zygote. (d) Shows isomorphic alternation of generation. 26. Which of the following is a heterosporus fern? (a) Salvinia (b) Selaginella (c) Dryopteris (d) Lycopodium 27. Recognise the label ‘X’ in the following plant. Dwarf shoot Long shoot

‘X’

(a) Naked ovule (c) Seed

(b) Fruit with few seeds (d) None of these

28. Which of the following is right code for matching shown in Column-I and Column-II? Column-I Column-II (i) Walking fern (p) Ginkgo (ii) Bogg moss (q) Cycas (iii) Living fossil (r) Adiantum caudatum (iv) Maiden hair tree (s) Sphagnum (a) (i)-r, (ii)-s, (iii)-p, (iv)-q (b) (i)-s, (ii)-r, (iii)-q, (iv)-p (c) (i)-r, (ii)-s, (iii)-q, (iv)-p (d) (i)-r, (ii)-q, (iii)-s, (iv)-p 29. Giant red wood tree is (a) Cedrus deodara (c) Rhododendron

(b) Eucalyptus regans (d) Sequoia.

30. In _____ , a dominant independent gametophyte alternates with a short lived, dependent sporophyte. (a) Volvox (b) Adiantum (c) Marchantia (d) Cedrus 31. Which of the following statements are false? (i) Pollen grains released at 3, 4 and 2-3 celled stage in Cycas, Pinus and angiosperms, respectively. (ii) Peat has long been used as fuel, is derived from aquatic moss Sphagnum. (iii) Bryophytes are of great ecological importance as they help in controlling soil erosion as well as soil formation during ecological succession. (iv) Male cone of Pinus is equivalent to flower of angiosperm. MT BIOLOGY

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(v) Endosperm of Cycas is a post fertilisation food laden product. (a) (v) only (b) (iv) and (v) (c) (iii), (iv) and (v) (d) (i) and (v) 32. Study the following diagrams very carefully and recognise them.

(i)

(a) (b) (c) (d)

(i) Polysiphonia Porphyra Porphyra Polysiphonia

(ii)

(ii) Fucus Fucus Laminaria Laminaria

(iii)

(iii) Salvia Salvinia Salvinia Salvia

(iv)

(iv) Equisetum Horsetail Equisetum Horsetail

33. All of the following are correct statements, except (a) W.r.t. gymnosperms, [spore → sporangium → sporophyll → strobilus] is correct pattern of arrangement of reproductive structures. (b) Most of the pteridophytes are homosporous and very few are heterosporous. (c) Bryophytes differ from pteridophytes by containing vascular tissue. (d) ‘Taxol’ an anticancer drug derived from bark of stem in plant Taxus baccata. 34. Leaves of conifers are well adapted to withstand extremes of temperature, humidity and wind, because of the following feature/s. (a) Acicular leaves (b) Absence of venation (c) Sunken stomata (d) All of these 35. Which of the following is a true statement? (a) Ferns are the first to appear after forest fire. (b) Chilgoza nuts are fruits of Pinus gerardiana. (c) Ovuliferous scale is equivalent to stamen. (d) Coralloid roots are associated with Anabaena for N2 fixation in Cycas, which are positively geotropic. 36. “Green multicellular asexual buds developing in a small receptacle on thalli” are called (a) bulbils, found in Selaginella (b) gemmules, found in sponges (c) gemmae, found in liverworts (d) reduction bodies, found in Sycon. 37. How many of the following features pertain(s) to gymnosperms? (i) Xylem commonly, lacks vessels and phloem lacks sieve tubes. 24

MT BIOLOGY

TODAY | JANUARY ‘16

(ii) (iii) (iv) (v) (a)

Lack pericarp, but, endosperm is haploid. Gametophyte parasite on sporophyte. Haplontic life cycle. Few members homosporus. 3 (b) 2 (c) 4 (d) 1

38. 1st cell in the life cycle of sporophyte and last cell in life of gametophyte, among ferns is (a) Spore and spore mother cell, respectively (b) Zygote and spore, respectively (c) Zygote and gametes, respectively (d) Spore and zygote, respectively. 39. Which of the following is an incorrect statement? (a) Sphagnum used as moss stick and for trans-shipment of live plants. (b) Mosses and lichens are air pollution indicators, as well as, 1st to colonise bare rocks. (c) Marchantia, a dioecious bryophyte has multicellular rhizoids. (d) In Funaria reductional division takes place in the theca region of capsule. 40. Which of the following is a wrong match? (a) Spermatophyte, without flowers and fruits – Gymnosperms. (b) Cryptogams, without seeds, with vascular tissue – Pteridophytes. (c) Thalloid plant body, abundant mitospores, non-vascular cryptogams, with jacketed sex organs - algae. (d) Seedless, non-vascular cryptogams with antheridia and archegonia – Bryophytes. 41. Gymnosperms contain (a) antheridia and no archegonia (b) antheridia and archegonia (c) no antheridia and no archegonia (d) archegonia and no antheridia. 42. Among pteridophytes Selaginella belongs to Class (a) Anthocerotopsida (b) Sphenopsida (c) Psilopsids (d) Lycopsida. 43. Archegonium of gymnosperm contains ____ neck canal cells. (a) 6-10 (b) 4-8 (c) One (d) Zero 44. Funaria may be differentiated from Pinus by the character(s) (a) no fruit is produced (b) no seed is produced (c) contains antheridia and archegonia (d) both (b) and (c). 45. Prothallus of fern contains (a) sporangia (b) strobilus (c) sorus (d) gametes.

46. Bryophytes are different from Fungi in having (a) terrestrial habitat (b) sterile jacket around sex organs (c) multiflagellate gametes (d) gametophytic body. 47. What is common in all the three, Funaria, Dryopteris and Ginkgo? (a) Independent sporophyte (b) Presence of archegonia (c) Well developed vascular tissues (d) Independent gametophyte 48. The spreading of living pteridophytes is limited to narrow geographical region because of (a) gametophytic growth needs cool, damp and shady place. (b) requirement of water for fertilisation. (c) absence of stomata in leaf and absence of vascular tissue. (d) both (a) and (b). 49. Deep in the tropical rain forest, a botanist discovered an unusual plant with vascular tissues, stomata, a cuticle, flagellated sperm, strobilus like reproductive structures bearing seeds and an alternation-of-generations in the life cycle. He was very excited about this discovery because it would be rather unusual for a plant to have both (a) a strobilus and flagellated sperm (b) vascular tissues and alternation of generations (c) seeds and flagellated sperm (d) alternation of generations and seeds. 50. Distinguishing feature of angiosperm is (a) production of seeds (b) poor adaptability to various environmental conditions (c) double fertilisation (d) pollination and siphonogamy. 51. Which of the following are correct statements? (i) Unique features to all mammals are mammary glands, hair on skin, diaphragm and ear pinnae. (ii) Protochordates include cephalochordates, urochordate and hemichordates. (iii) Annelids are metamerically segmented with schizocoelom. (iv) All chordates are vertebrates. (v) Reptiles are characterised by cornified skin. (a) (i), (ii), (iii) and (v) (b) (ii), (iii) and (v) (c) (i), (iii) and (v) (d) (iii) and (v) 52. How many of the following matches are wrong? (i) Marine animals with comb plates – Ctenophora. (ii) Animals containing canal system – Echinoderms. (iii) Pseudocoelomates with some parasites – Aschelminthes.

(iv) Most primitive vertebrates, ectoparasite on fish – Cyclostomata. (v) Fish, amphibians and reptiles – Anamniotes. (a) 2 (b) 3 (c) 1 (d) None 53. Hemichordates have following body parts (a) head, trunk and tail (b) head, foot and visceral mass (c) cephalothorax and abdomen (d) proboscis, collar and trunk. 54. How many of the following matches are correct? (i) Uropygeal gland – Birds (ii) Collar cells – Sycon (iii) Well developed keel – Struthio (iv) Placoid scales – Chondrichthyes (v) Swim bladder – Scoliodon (a) 5 (b) 4 (c) 3 (d) 2 55. Metameric segmentation is found in (a) Annelida (b) Chordata (c) Arthropoda (d) all of these. 56. Which of the following are true matches? (i) Amphioxus – Flame cells (ii) Crop and Gizzard – Birds (iii) Collar cells – Water vascular system (iv) Colloblasts – Ctenophora (v) Tornaria larva – Balanoglossus (a) (i), (ii) and (iv) only (b) (iii), (iv) and (v) only (c) (i), (ii) and (iii) only (d) (i), (ii), (iv) and (v) 57. Which of the following taxa contains bilaterally symmetrical larva and radially symmetrical adult? (a) Hemichordata (b) Echinodermata (c) Protochordates (d) Cnidaria 58. Which of the following animals contains alimentary canal, but, lacks anus? (a) Fasciola (b) Taenia (c) Dog tape worm (d) Amphioxus 59. Filaria disease is caused by (a) female Culex (b) female Anopheles (c) female Aedes (d) none of these. 60. Which of the following excretory organ and the animal is correctly matched? (a) Proboscis gland – Balanoglossus (b) Green gland – Amphioxus (c) Kidney – Prawn (d) All of these 61. Bilateral symmetry, worm like body, circular in T.S., sexual dimorphism, pseudocoelomate, coenocytic epithelium, is a group of characters, shown by MT BIOLOGY

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25

(a) tapeworm (c) earthworm

(b) Ascaris (d) sandworm.

70. Identify the following animals and the classes to which they belong.

62. Which of the following is not an Echinoderm? (a) Sea urchin (b) Sea fan (c) Sea lily (d) Sea cucumber 63. Nematoblast is an organ of (a) offence (b) anchorage (c) defence (d) all of these. 64. Which of the following is a correct statement? (a) Infective stage of Ascaris in human is egg. (b) Vector for Wuchereria bancrofti is male Culex mosquito. (c) Walking worm is Peripatus, connecting link between Arthropoda and Mollusca. (d) Chloragogen cells of earthworm are equivalent to pancreas of human. 65. Which of the following is a wrong statement? (a) Nereis is dioecious and has parapodia for swimming. (b) Locust is a colonial arthropod. (c) Limulus is commonly called king crab. (d) Pinctada is a pearl forming mollusac. 66. Which of the following arthropods does not act as vector of human diseases? (a) Xenopsella cheopsis (b) Glossina palpalis (c) Phlebotomus argentipus (d) Male Aedes mosquito 67. Match List-I (larval forms) with List-II (corresponding adults) and select the correct answer using the codes given. List-I List-II A. Tornaria (i) Nereis B. Brachiolaria (ii) Balanoglossus C. Axolotl (iii) Starfish D. Trochophore (iv) Salamander (a) A-(ii), B-(iii), C-(i), D-(iv) (b) A-(ii), B-(iii), C-(iv), D-(i) (c) A-(iii), B-(ii), C-(iv), D-(i) (d) A-(i), B-(ii), C-(iii), D-(iv) 68. Osphradium of Pila helps in (a) osmoregulation (b) rasping (c) chemoreception (d) excretion. 69. Which of the following is a wrong match? (a) Central vascular cavity of Hydra – Coelenteron (b) Neophron in human are functional unit of kidney. (c) Endoskeleton fully ossified and long bones pneumatic in flying birds. (d) Duckbilled platypus is a monotreme mammal, a connecting link between reptiles and mammals. 26

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A

B

C

(a) A-Salamandra, Amphibia; B-Testudo, Reptilia; C-Chameleon, Reptilia (b) A-Salamandra, Reptilia; B-Chelone, Reptilia; C-Garden lizard, Reptilia (c) A-Salamandra, Amphibia; B-Chelone, Reptilia; C-Tree lizard, Reptilia (d) A-Salamandra, Reptilia; B-Testudo, Reptilia; C-Chameleon, Wall lizard 71. Match column-I with column-II and select the correct option from the codes given. Column-I Column-II A. Protochordata (i) Delphinus B. Limbless amphibian (ii) Myxine C. Oviparous mammal (iii) Ornithorhynchus D. Aquatic mammal (iv) Doliolum E. Jawless vertebrate (v) Ichthyophis (a) A-(v), B-(iv), C-(iii), D-(i), E-(ii) (b) A-(iv), B-(v), C-(iii), D-(i), E-(ii) (c) A-(iv), B-(v), C-(iii), D-(ii), E-(i) (d) A-(v), B-(iii), C-(i), D-(ii), E-(iv)

1.

Make as many biological terms as possible using the given letters. Each word should contain the letter given in circle. 2. Minimum 4 letter word should be made. 3. In making a word, a letter can be used as many times as it appears in the box. 4. Make at least 1 seven letter word.

O G

R I

E

O P

S

Z

T Y H M O N

E

A

Send your response at [email protected] or post to us with complete address by 25th of every month to win exciting prizes. Winners’ name from October issue onwards will be declared on 1st of every month on www.mtg.in

72. Select the correct option in respect of characteristics of each group. Cyclostomes (i) Sucking mouth (ii) Scales absent (iii) Marine

Chondrichthyes Ventral mouth Placoid scales Marine

Osteichthyes Terminal mouth Cycloid/Ctenoid scales Mostly fresh water, some marine (iv) 6-15 pairs of gills 5-7 pairs of gills 4 pairs of gills with without operculum operculum

(a) (i) and (ii) are correct (b) (i) and (iv) are correct (c) All are correct (d) Only (iii) is correct 73. Which of the following groups of animals are uricotelic? (a) Reptiles, birds, land snails and terrestrial insects (b) Reptiles, birds, land snails, all crustaceans. (c) Aquatic amphibians, birds, land snails, insects (d) Amphibians, reptiles, birds, insects 74. Which of the following statements is correct for all sponges without exception? (a) They all have calcareous spicules. (b) They have high regeneration power. (c) They are found only in cold marine water. (d) They are all radially symmetrical. 75. The figures (A-D) show four animals. Select the correct option with respect to a common characteristic of two of these animals.

77. The figures given below show the types of coelom. Identify them and select the correct group of organisms which possess them.

A

(a) (b) (c) (d)

B

A Annelids Molluscs Echinoderms Echinoderms

B Aschelminthes Arthropods Aschelminthes Arthropods

C

C Platyhelminthes Platyhelminthes Annelids Platyhelminthes

78. Which of the following group is formed of only the hermaphrodite organisms? (a) Earthworm, tapeworm, housefly, Nereis (b) Earthworm, tapeworm, sea horse, Nereis (c) Earthworm, leech, sponge, roundworm (d) Earthworm, tapeworm, leech, sponge 79. You have discovered an animal having characters like triploblastic, bilateral symmetry, coelomate, chitinous exoskeleton, head, thorax and abdomen as body parts, and jointed appendages. You should place the animal under (a) Tetrapoda (b) Arthropoda (c) Annelida (d) Hemichordata. 80. Post anal tail is found in (a) snails (b) scorpion (c) snakes (d) all of these. ASSerTIOn & reASOn

A

(a) (b) (c) (d)

B

C

D

A and D respire mainly through body wall. B and C show radial symmetry. A and B have cnidoblasts for self-defence. C and D have a true coelom.

76. Which one of the following groups of three animals is correctly matched with their one characteristic morphological feature? Animals (a) Scorpion, spider, cockroach (b) Cockroach, locust, Taenia (c) Liver fluke, sea anaemone, sea cucumber (d) Centipede, prawn, sea urchin

Morphological features Ventral solid central nervous system Metameric segmentation Bilateral symmetry

Jointed appendages

In this type of questions, a statement of assertion (A) is followed by a statement of reason (R). Mark the correct choice as : (a) If A and R both are correct and R is the correct explanation of A. (b) If A and R both are correct but R is not the correct explanation of A. (c) If A is true but R is false. (d) If both A and R are false. 81. Assertion : Deuteromycetes are commonly known as imperfect fungi. Reason : In Deuteromycetes, only asexual and vegetative phases are known. 82. Assertion: The cell wall of diatoms is indestructible. Reason: The cell wall of diatoms is embedded with calcium carbonates. 83. Assertion: In Ascomycetes and Basidiomycetes well distinct dikaryophase is present during sexual life. MT BIOLOGY

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Reason: During sexual reproduction of Ascomycetes and Basidiomycetes, plasmogamy is immediately followed by karyogamy. 84. Assertion: Rhodophycean algae can show change in their colour as per their presence on surface or bottom of water reservoir. Reason: Rhodophycean have ability of complementary chromatic adaptation. 85. Assertion: Sporophyte of bryophytes is dependent on gametophyte. Reason: Sporophyte of bryophytes lacks root like structures to absorb nutrition from damp soil. 86. Assertion: Living pteridophytes are limited and restricted to narrow geographical regions.

87.

88.

89.

90.

Reason: Pteridophytes do not form seeds. Assertion: Gymnosperms are first completely successful land plants. Reason: In gymnosperms vascular tissue is present. Assertion: The body of reptiles is covered by dry and cornified skin, epidermal scales or scutes. Reason: Reptiles are true terrestrial vertebrates. Assertion: Polyps produce medusae sexually and medusae form the polyps asexually. Reason: Polyps and medusa are the common feature of different group of cnidarians. Assertion: All the members of platyhelminthes are protostomes. Reason: Mouth is formed by blastopore in these animals.

CLASS XII 91. Which of the following statements are true? A. Four typed layers of cells, in the wall of angiospermic microsporangium, are named as tapetum, middle layers, endothecium and epidermis from outer to inner side. B. Apomictic embryos of Citrus and mango seeds are clone of their parent. C. Fruits produced from ovaries without the act of fertilisation are called parthenogenetic. D. Ovary wall mature into testa. E. In angiospermic plant endosperm development proceeds the development of embryo. (a) A, B and E (b) B, C and E (c) B, D and E (d) B only 92. To produce 96 male gametes in angiosperms, minimum number of meiosis required are (a) 24 (b) 48 (c) 12 (d) 96. 93. Coffee is derived from perisperm of seed, which is (a) enlarged nucleus of PEC (b) remains of endosperm of seed (c) remnants of nucellus (d) modified inner integument of ovule. 94. How many of the following statements are true? (i) Tassels of maize are, sticky stigma containing, styles. (ii) Cleistogamy ensures seed setting but decreases hybrid vigorous. (iii) Geitonogamy in bisexual flowers is functional cross pollination but genetical self pollination. (iv) Eichhornia produces purple flowers and is pollinated by bees. (v) Dioecy is a device to ensure cross pollination (a) 5 (b) 4 (c) 3 (d) 2. 28

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95. Which of the following is a correct sequence during life cycle of angiosperm for the following terms/events? A. Pollen grain B. Sporogenous tissue C. Microspore tetrad D. PMC E. Male gamete (a) B → D → C → A → E (b) B → C → D → A → E (c) C → B → D → A → E (d) C → D → B → A → E 96. Which of the following is a correct statement? (a) Double fertilisation was discovered by Nawaschin from Monotropa plant. (b) Polygonum type of embryosac is bisporic, 7 celled 8 nucleate. (c) Most common typed endosperm in angiosperm is nuclear typed. (d) Epiblast is reduced coleoptile of grasses. 97. Shown diagram is a fertilised embryo sac. Which of the following is true about it? C

A

B

(a) A-produced by fusion of 2 cells and 3 haploid nuclei called PEN.

(b) B-degenerating 3 haploid cells of micropylar region. (c) C-Growing embryo and degenerating antipodals. (d) A-produces 3n food ladden tissue.

105. Choose correct option for A, B, C and D of a dicot embryo. Plumule A

98. Which of the following is a true match, except? (a) Carpel – Modified megasporangium. (b) Michelia – Polycarpellary apocarpus gynoecium. (c) Callose – Polysaccharide found in thickenings of endothecial wall. (d) Ubisch’s granules – Produces exine. 99. Site of origin of integument in angiospermic ovule is (a) raphe (b) chalaza (c) hilum (d) funicle. 100. How many of the following listed plants will produce nonendospermic seeds? Castor, Barley, Orchids, Groundnut, Maize, Pea, Mustard, Wheat (a) 3 (c) 5

(b) 6 (d) 4

101.In most of the water pollinated angiospermic species, pollen grains are protected from wetting by (a) lipid rich, yellowish, pollen–kit (b) exine formed of resistant substance sporopollenin (c) mucilaginous covering (d) any of the above depending upon species. 102.Which of the following is a true statement, except. (a) Stamen is a modified microsporophyll and ovule is a megasporangium. (b) Typical anther is dithecous, tetrasporangiate and tetragonal and its microsporangium is eusporangiate. (c) Pollinium contain all pollens produced in one anther lobe and found in orchids. (d) Bending of pollen tube towards synergid is a chemotactic movement. 103. Male plant 6n and female plant 4n takes part in sexual reproduction. Which of the following is true match? (a) Aleurone grain layer cell – 7n (b) Nucellus – 6n (c) PEN – 8n (d) Cells in epidermis of root in next generation – 4n 104.Which of the following statements is untrue? (a) In angiosperms pollen grain commonly released at 3 celled stage. (b) Most common typed ovule among angiosperm is anatropus. (c) 5 nuclei participate in double fertilisation. (d) Pollen allergy is caused by Parthenium heterophorus.

B

D C

(a) (b) (c) (d)

A-Hypocotyl; B-Cotyledons; C-Root cap; D-Radicle A-Cotyledons; B-Hypocotyl; C-Root cap; D-Radicle A-Cotyledons; B-Hypocotyl; C-Radicle; D-Root cap A-Cotyledons; B-Radicle; C-Hypocotyl; D-Root cap

106. Sequence of development during the formation of embryo sac is (a) Archesporium → Megaspore → Megaspore mother cell → Embryo sac. (b) Megasporocyte → Archesporium → Megaspore → Embryo sac. (c) Megaspore → Megaspore mother cell → Archesporium → Embryo sac. (d) Archesporium → Megaspore mother cell → Megaspore → Embryo sac. 107.Total number of meiotic divisions required for production of 100 grains in maize is (a) 25 (b) 100 (c) 125 (d) none. 108.During siphonogamy of angiosperm pollen tube enters embryo sac through (a) filiform apparatus of egg (b) through healthy and persistent synergid (c) through degenerating synergid (d) through haustorial outgrowth of synergid. 109.Which of the following are incorrectly matched? (i) Palynology – Study of pollen markings (ii) Stomium – Present in the line of dehiscence of anther. (iii) Canthrophily – Pollination by beetle. (iv) Vallisneria – Epihydrophily. (v) Papaya – Monoecious plant. (a) (i), (iii) and (v) (b) (iii) and (v) (c) (iii), (iv) and (v) (d) (v) only 110.During polyembryony in Citrus, extra embryo arise from (a) both integument and nucleus (b) synergids and antipodals (c) nucellus and antipodals (d) nucellus only. 111.(A) Family planning programmes initiated in India in 1971. (B) According to the 2001 census of Indian population, growth rate was about 1.7%. Indian population will become double by the year 2034, a prediction. MT BIOLOGY

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(C) Saheli – an oral contraceptive pill, used once a week is rich in estrogen – progrestogen combination. (D) Hepatitis, genital herpes and HIV infection are incurable. (E) Gonorrhea, syphilis and trichomoniasis are bacterial STDs. How many of the above statements are false? (a) 3 (b) 2 (c) 4 (d) 1 112.Most common contraceptive used by Indian women is IUDs, but, LNG-20, a contraceptive (a) is one typed lubricated condom enrich with spermicides (b) is one typed copper releasing IUD (c) makes uterus unsuitable for implantation (d) is one typed barrier method of contraception. 113.How many of the following statements are false? A. If STD is not timely detected and cured, it may lead to complication like PID, ectopic pregnancy, even cancer of the reproductive tract. B. In tubectomy conduction of gamete is interrupted and insemination is prevented. C. Oral contraceptive inhibits ovulation, implantation, as well as alter the quality of cervical mucus to retard entry of sperm. D. Amniocentesis, mainly, used to detect prenatal abnormalities of chromosomes leading to various syndromes. E. RCH stands for “Reversible Contraceptive Hazards”. (a) 2 (b) 3 (c) 1 (d) 4 114.To form embryo in vitro, the male gamete is transferred into female gamete directly. Such a technique is called (a) GIFT (b) ICSI (c) IVF-ET (d) IUI. 115.Technique GIFT is recommended for those females who (a) can’t provide suitable environment for fertilisation (b) can’t produce ovum (c) can’t retain foetus long enough in uterus to complete gestation (d) cervical canal too narrow to allow passage for the sperms. 116.Which of the following statements are true w.r.t. shown method of contraceptive device?

C. D. E. (a) (c)

Rarely adopted by Indian males from well to do families. May lead to impotency. Almost non reversible. A and E only (b) A, C and E A, B and C (d) All except C

117.Match column-I with column-II and select the correct option from the codes given below. Column-I Column-II A. Natural methods (i) Coitus interruptus B. IUDs (ii) LNG-20 C. Barrier methods (iii) Diaphragms D. Surgical methods (iv) Multiload 375 E. Oral contraceptive (v) Saheli (vi) Nirodh (vii) Sterilisation (viii) Vasectomy (ix) CuT (a) A-(i); B-(ii), (iv), (ix); C-(iii), (vi); D-(vii), (viii); E-(v) (b) A-(i); B-(ii), (iv); C-(iii), (vi), (ix); D-(vii), (viii); E-(v) (c) A-(i); B-(ii), (iv), (ix); C-(iii), (ix); D-(vii), (viii); E-(v), (vi) (d) A-(i); B-(iv), (ix); C-(ii), (iii), (vi); D-(vii), (viii); E-(v) 118. Intensely lactating mothers do not generally conceive due to the (a) suppression of gonadotropins (b) hypersecretion of gonadotropins (c) suppression of gametic transport (d) intense production of luteinising hormone. 119.Which of the following is a correct match w.r.t. menstrual cycle? (a) Menstrual phase – Break down of perimetrium of uterus along with blood vessels which forms liquid that comes out through vagina along with unfertilised ovum. (b) Luteal phase – A temporary endocrine gland placenta is formed which released LH to maintain endometrium allow proper implantation and other events of gestation. (c) Follicular phase – Secretion of gonadotropin increase leads to development of mature graafian follicle ready for ovulation. (d) Ovulatory phase – Surge in secretion of luteinising hormone to its maximum, rupturing of Graafian follicle, release of egg at primary oocyte. 120. Parturition is induced by complex neuroendocrine mechanism involving hormone(s) such as (a) cortisol (b) estrogen (c) oxytocin (d) all of the above

A. Semen will be mixture of secretion from prostrate gland, seminal vesicles and bulbourethral glands only. B. Can prevent transmission of STD’s.

121.Which of the following are false statements? (i) Typically ovulation takes place on 14th day of menstruation cycle, oocyte will be at metaphase II stage. (ii) Out of ejaculated sperms 48-72 million sperms must show vigorous motality for normal fertility. Contd. on page no. 75

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Class-12

PMT FOUNDATION

Maximise your chance of success and your seat in AIPMT and other PMTs by reading this column. This section is specially designed to optimise your preparation by practising more and more. It is a unitwise series having chapterwise question bank, allowing you to prepare systematically and become more competent. Recall question or single concept question – indicated by a single finger. Application question or question which requires 2 or 3 concepts to solve - indicated by 2 fingers. Application question or question which requires 3 or more concepts - indicated by 3 fingers.

unIT-VI : rePrODucTIOn chAPTer-1 : rePrODucTIOn In OrGAnIsms

multiple choice Questions 1. Find out correct order of vegetative propagules of plants like potato, ginger, Agave, Bryophyllum and water hyacinth. (a) Offset, bulbil, leaf bud, rhizome and eyes (b) Leaf bud, bulbil, offset, rhizome and eyes (c) Eyes, rhizome, bulbil, leaf bud and offset (d) Rhizome, bulbil, leaf bud, eyes and offset 2. In which one pair both the plants can be vegetatively propagated by leaf species? (a) Agave and Kalanchoe (b) Bryophyllum and Kalanchoe (c) Asparagus and Bryophyllum (d) Chrysanthemum and Agave 3. Oestrous cycle is reported in (a) cows and sheep (b) humans and monkeys (c) chimpanzees and gorillas (d) none of these 4. Vegetative reproduction by layering is found in (a) rose (b) jasmine (c) mango (d) all of these 5. The growth phase of an organism before attaining sexual maturity is referred to as (a) juvenile phase (b) vegetative phase (c) both (a) and (b) (d) none of these

6. Which of the following four phases, in the post emergence life of an angiospermic plant, begins just after germination of seed and ends when the plant develops the capacity to reproduce? (a) Death (b) Maturity (c) Ageing (d) Juvenility 7. Fusion of two organisms is called (a) homogamy (b) syngamy (c) allogamy (d) hologamy. 8. Gametogenesis refers to the process of (a) fusion of two gametes (b) fusion of two gametangia (c) formation of two types of gametes (d) formation of male gamete only. 9. Choose the correct pair. (a) Coconut, Cucurbits - dioecious (b) Honeybee, Rotifers - parthenogenesis (c) Ornithorhynchus, Whale - viviparity (d) Frog, Peacock - external fertilisation 10. Product of sexual reproduction generally generates (a) new genetic combination leading to variation (b) large biomass (c) longer viability of seeds (d) prolonged dormancy. MT BIOLOGY

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True or False

Passage Based Questions

11. Asexual reproduction is common among single-celled organisms, and in plants and animals with relatively simple body organisation.

23.(A) Complete the given passage with appropriate words or phrases. In flowering plants, the (i) is formed inside the ovule. After (ii) , the sepals, petals and (iii) of the flower wither and fall off. The (iv) remains attached to the plant. The zygote develops into the (v) and the ovules develop into the (vi) . The (vii) develops into the fruit which develops a thick wall called (viii) .

12. Asexual reproduction involves formation of the male and female gametes, either by the same individual or by different individuals of the opposite sex. 13. The reproduction by zoospores occur in some lower fungi like phycomycetes and some algae. 14. In anisogamy, fusing gametes differ in size or motility. 15. In monoecious plant, both male and female flowers are present on different plants. 16. Monocarpic plants flower only once in their life and die after producing fruits. 17. Endogamy involves the fusion of two gametes produced by different parents. 18. Embryogenesis is the formation and development of a multicellular embryo from unicellular zygote. 19. In arrhenotoky type of parthenogenesis, only females are produced by parthenogenesis. 20. In oviparous animals, the zygote develops into a young one inside the body of the female organisms.

match The columns 21. Match Column I with Column II. A. B. C. D. E.

Column I Conidia Polyembryony Offsets Arrhenotoky Zoospores

(i) (ii) (iii) (iv) (v)

Column II Eichhornia Rotifers Penicillium Chlamydomonas Armadillo

22. Match Column I with Column II. (There can be more than one match for items in Column I) A. B. C. D. E.

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Column I Binary fission Dioecious plants Parthenogenesis Sporangiospores Corms

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(i) (ii) (iii) (iv) (v) (vi) (vii) (viii) (ix) (x)

Column II Date palm Apus Amoeba Rhizopus Colocasia Crocus Euglena Mucor Papaya Cypis

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(B)

Read the given passage and correct the errors, wherever present. The process of formation of male and female gametes is called sporogenesis. Gametes are diploid cells. In some algae, the two gametes are similar in appearance and are called anisogametes. In most of asexually reproducing organisms the gametes are of morphologically dissimilar types, hence, they are known as isogametes. In anisogametes the male gamete is called the egg and the female gamete is known as the antherozoid.

Assertion & reason In each of the following questions, a statement of Assertion (A) is given and a corresponding statement of Reason (R) is given just below it. Of the statements, mark the correct answer as : (a) if both A and R are true and R is the correct explanation of A (b) if both A and R are true but R is not the correct explanation of A (c) if A is true but R is false (d) if both A and R are false. 24. Assertion : In external fertilisation, gametes are released in water in large numbers. Reason : Gametes released in water in external fertilisation are subjected to harsh environmental conditions. 25. Assertion : Chlamydospores store reserve food material and are capable of withstanding long unfavourable conditions. Reason : Chlamydospores are thin walled spores produced directly from hyphal cells. 26. Assertion : Coconut is a dioecious plant. Reason : In coconut, male and female flowers are present on different plants. 27. Assertion : In binary fission a parent cell divides into two identical daughter cells. Reason : The nucleus of the parent body divides repeatedly during binary fission.

28. Assertion : Non-primate females permit copulation only during oestrous period. Reason : During oestrous period, sex urge is increased.

Figure Based Questions 29. Refer to the given figure and answer the following questions.

3. If the number of chromosome in root cell is 14, then what will be the chromosome number in synergids? (a) 14 (b) 21 (c) 7 (d) 28

A

4. The portion of embryonal axis above cotyledon is called as (a) epicotyl (b) hypocotyl (c) coleoptile (d) radicle.

B

5. Exine of pollen grain is made up of (a) pectocellulose (b) lignocellulose (c) sporopollenin (d) pollen kit.

C

....... .... .. .. .. (a) Identify A, B and C in the given figure. (b) Briefly describe the process of A, B and C. 30. Refer to the given figures and answer the following questions.

A

2. During the process of sexual reproduction in flowering plants, double fertilisation involves (a) fertilisation of egg cell by two male gametes (b) fertilisation of egg cell and a central cell by two male gametes brought by same pollen tube (c) fertilisation of egg cell and a central cell by two male gametes brought by different pollen tubes (d) fertilisation of two egg cells by two male gametes brought by same pollen tube.

B

(a) Identify figures A and B. (b) Briefly describe figures A and B. chAPTer-2 : sexuAL rePrODucTIOn In FLOwerInG PLAnTs

multiple choice Questions 1. Which of the following feature(s) is/are common to both wind and water pollinated flowers? I. Pollen grains are long and ribbon-like. II. Stigma is large and feathery. III. The flowers are not colourful. IV. The flowers do not produce nectar. (a) III and IV only (b) II and III only (c) I and II only (d) II only

6. Entry of pollen tube through the chalazal end is called (a) porogamy (b) mesogamy (c) chalazogamy (d) syngamy. 7. If 400 pollen grains are produced in a single monothecous anther then, what was the number of pollen grain mother cells in each of the sporangia ? (a) 200 (b) 100 (c) 50 (d) 25 8. Apomixis is (a) formation of seeds by fusion of gametes (b) formation of seeds without syngamy and meiosis (c) formation of seeds with syngamy but no meiosis (d) none of the above 9. Identify the wrong statement regarding post-fertilisation development. (a) The ovary wall develops into pericarp. (b) The outer integument of ovule develops into tegmen. (c) The fusion nucleus (triple nucleus) develops into endosperm. (d) The ovule develops into seed. 10. The sequence of development of embryo sac is (a) archesporium → megaspore → embryo sac → megasporangium (b) archesporium → megaspore → megaspore mother cell → embryo sac (c) archesporium → megaspore mother cell → megaspore → embryo sac (d) megaspore mother cell → archesporium → megaspore → embryo sac. MT BIOLOGY

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in the (iii) towards micropylar half of the ovule. The typical and most common type of (i) is (iv) type. It contains (v) nuclei but (vi) cells – (vii) micropylar, (viii) chalazal and one (ix) .

True or False 11. Epicotyl is the part of embryonal axis in between cotyledonary node and radicle. 12. Solid style has a special tissue of pectinised thick walls known as transmitting or conducting tissue. 13. Xenogamy is transfer of pollen grains from the anther to the stigma of another flower of the same plant. 14. Occurrence of more than one embryo in a seed is referred to as polyembryony. 15. Cleistogamous flowers always remain closed so that anthers and stigmas are never exposed. 16. Intine is inner layer of pollen grain made up of sporopollenin. 17. The wall of ovary develops into the wall of fruit called pericarp. 18. Innermost wall layer of microsporangium is endothecium which nourishes the developing pollen grain. 19. Non-albuminous seeds have no residual endosperm as it is completely consumed during embryo development. 20. The synergids have special cellular thickenings at the micropylar tip called filiform apparatus.

match The columns 21. Match Column I with Column II. Column I A. Ategmic ovule (i) B. Homogamy (ii) C. Ruminate endosperm (iii) D. Hydrophily (iv) E. Tritegmic ovule (v)

Column II Areca Zostera Santalum Catharanthus Asphodelus

22. Match Column I with Column II. (There can be more than one match for items in Column I) Column I Column II A. Stamen (i) Syngamy B. Double fertilisation (ii) Anther C. Sporoderm (iii) Intine D. Seed coat (iv) Triple fusion E. Dichogamy (v) Filament (vi) Protandry (vii) Testa (viii) Protogyny (ix) Exine (x) Tegmen

Passage Based Questions 23.(A) Complete the given passage with appropriate words or phrases. In angiosperms, the female gametophyte is called (i) . It is an oval multicellular (ii) structure which is embedded 34

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(B)

Read the given passage and correct the errors, wherever present. Seed and fruit formation are stimulated by the act of pollination. In angiosperms this process produces two structures – a haploid zygote and a diploid endosperm cell. The zygote gives rise to a nutritive tissue and endosperm cells forms the embryo. With the growth of embryo the peripheral part of the nutritive tissue is eaten up. Nutritive tissue in turn crushes the micropyle.

Assertion & reason In each of the following questions, a statement of Assertion (A) is given and a corresponding statement of Reason (R) is given just below it. Of the statements, mark the correct answer as : (a) if both A and R are true and R is the correct explanation of A (b) if both A and R are true but R is not the correct explanation of A (c) if A is true but R is false (d) if both A and R are false. 24. Assertion : Megasporogenesis is meiotic formation of haploid megaspores from diploid megaspore mother cell. Reason : The arrangement of megaspores in a tetrad is commonly tetrahedral. 25. Assertion : Cross pollination involves the transfer of pollen from anther of one flower to the stigma of a genetically different plant. Reason : In dichogamy the anthers and stigmas mature at different times. 26. Assertion : Scientists are trying to identify genes for apomixis. Reason : Increasing cost of hybrid crop production can be avoided if apomictic genes can be introduced in hybrid seeds. 27. Assertion : Emasculation is not required in unisexual flowers. Reason : Emasculation is the removal of stamens from the floral buds of bisexual flowers to eliminate chances of self pollination. 28. Assertion : Orinithophilous flowers are generally dull coloured with strong fermenting or fruity odour, abundant nectar and pollen grains. Reason : Ornithophily is cross pollination performed by insects.

Figure Based Questions 29. Refer to the given figure and answer the following questions. A B

C

D

(a) Identify A, B, C and D in the given figure. (b) Briefly describe part B and D. (c) Which labelled part represent rudiments of second cotyledon? 30. Refer to the given figure and answer the following questions. A

B C D

(a) Identify A, B, C and D in the given figure. (b) Which labelled part is known as fibrous layer? (c) Write the function of labelled part D. chAPTer-3 : humAn rePrODucTIOn

multiple choice Questions 1. In humans, what is the ratio of number of gametes produced from one male primary sex cell to the number of gametes produced from one female primary sex cell? (a) 1 : 4 (b) 1 : 1 (c) 4 : 1 (d) 1 : 3 2. The correct sequence of embryonic development is (a) Blastula - Morula - Zygote - Gastrula (b) Zygote - Blastula - Morula - Gastrula (c) Zygote - Morula - Blastula - Gastrula (d) Gastrula - Morula - Zygote - Blastula. 3. Sperm of animal species A cannot fertilise ovum of species B because

(a) fertilizin of A and antifertilizin of B are not compatible (b) antifertilizin of A and fertilizin of B are not compatible (c) fertilizin of A and B are not compatible (d) antifertilizin of A and B are not compatible. 4. Choose the correct statement. (a) hPL plays a major role in parturition. (b) Foetus shows movements for the first time in the 7th month of pregnancy. (c) Signal for parturition comes from fully developed foetus and placenta. (d) Embryo’s heart is formed in the 5th month of pregnancy. 5. Starting from the maximum, arrange the following male reproductive accessory organs in the correct order, based on the amount of secretion. (i) Prostate glands (ii) Seminal vesicles (iii) Bulbourethral glands (a) (i) > (ii) > (iii) (b) (iii) > (ii) > (i) (c) (ii) > (iii) > (i) (d) (ii) > (i) > (iii) 6. Which of the following hormone stimulates Sertoli cells? (a) FSH (b) Estrogen (c) ACTH (d) Testosterone 7. Which of these combinations is most likely to be present before ovulation occurs? (a) FSH, corpus luteum, oestrogen, secretory uterine lining (b) LH, corpus luteum, progesterone, secretory uterine lining (c) FSH, Graafian follicle, oestrogen, uterine lining becoming thick (d) Luteinizing hormone (LH), Graafian follicle, progesterone, thick uterine lining 8. LH surge occurs during which phase of the menstrual cycle? (a) Menstrual phase (b) At the beginning of proliferative phase (c) Just before the end of the luteal phase (d) Ovulatory phase 9. The foetal ejection reflex in humans triggers the release of (a) oxytocin from foetal pituitary (b) human chorionic gonadotropin (hCG) from placenta (c) human placental lactogen (hPL) from placenta (d) oxytocin from maternal pituitary. 10. Acrosome of sperm is derived from (a) centriole (b) endoplasmic reticulum (c) Golgi bodies (d) peroxisome. MT BIOLOGY

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The process of fusion of a sperm with an ovum is called fertilisation. During fertilisation, a sperm comes in contact with the (i) layer of the ovum and induces changes in the membrane that (ii) the entry of additional (iii) . The secretions of the (iv) help the sperm enter into the (v) of the ovum. This induces the completion of the (vi) division of the (vii) .

True or False 11. Insemination is the transfer of sperms by the male into the genital tract of the female. 12. Sertoli cells secrete androgen binding protein that concentrates testosterone in the seminiferous tubules. 13. Spermatogenesis is the process of the transformation of spermatids into spermatozoa. 14. During embryonic development, a solid ball-like structure which looks like a little mulberry is known as blastula. 15. In ovulatory phase, both LH and FSH attain a peak level. 16. Chorion is composed of trophoblast present on inner side and somatopleuric extraembryonic mesoderm present towards the outerside. 17. Teratogens are certain agents or drugs that cause abnormal development of embryo. 18. Depolarisation of oocyte plasma membrane prevents polyspermy and ensures monospermy. 19. Vasa efferentia carries spermatozoa from cauda epididymis to the ejaculatory duct. 20. Colostrum contains several antibodies that provide passive immunity to the new born babies.

match The columns 21. Match Column I with Column II. Column I Column II A. Leydig cells (i) Implantation of blastocyst B. Placenta (ii) Progesterone C. Endometrium (iii) Fructose D. Seminal vesicles (iv) Androgen E. Oviducts (v) Fallopian tube 22. Match Column I with Column II. (There can be more than one match for items in Column I) Column I Column II A. Male sex accessory (i) Relaxin ducts B. Corpus luteum (ii) Seminal vesicles C. Male accessory glands (iii) Rete testis D. Ovarian stroma (iv) Progesterone E. Chorionic placenta (v) Epididymis (vi) Medulla (vii) Bulbourethral gland (viii) Chorion (ix) Decidua basalis (x) Cortex

Passage Based Questions 23.(A) Complete the given passage with appropriate words or phrases. 36

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(B)

Read the given passage and correct the errors, wherever present. The mature ovum or a female gamete is tubular in shape. The human ovum is said to be mesolecithal. Its cytoplasm is called acroplasm containing mitochondria, termed as mitochondrial vesicle. There are many centrioles in the ovum. The cytoplasm is enveloped by the plasma membrane and very large vesicles called cortical granules are present below it. A wide perivitelline space is present inside the plasma membrane.

Assertion & reason In each of the following questions, a statement of Assertion (A) is given and a corresponding statement of Reason (R) is given just below it. Of the statements, mark the correct answer as : (a) if both A and R are true and R is the correct explanation of A (b) if both A and R are true but R is not the correct explanation of A (c) if A is true but R is false (d) if both A and R are false. 24. Assertion : Sex in human beings is determined by the father. Reason : The set of sex chromosome present in the human female is XY and male is XX. 25. Assertion : Trophoblast forms the foetal part of placenta and does not form any part of the embryo proper. Reason : Trophoblast is the outermost layer of cells of a blastocyst. 26. Assertion : Colostrum provides passive immunity to the new born infant. Reason : Colostrum contains antibodies, having IgA as the major immunoglobulin. 27. Assertion : Sertoli cells are present in between the seminiferous tubule. Reason : Sertoli cells are found in small groups and are rounded in shape. 28. Assertion : Primary oocytes are formed from the oogonia in the ovary of the foetus. Reason : Each primary oocyte forms two ovum and two polar bodies.

Figure Based Questions 29. Refer to the given figure and answer the following questions. E B

F

A

C D

(a) Identify the labelled parts A, B, C, D, E and F. (b) Name the hormone secreted by the labelled part A and write its one function. (c) Briefly describe the role of hormone secreted by labelled part D. 30. Refer to the given figure and answer the following questions.

(b) prevents the production of semen (c) prevents the movement of sperms into the urethra (d) prevents a man from having an erection. 3. Which one of the following groups includes all sexually transmitted diseases? (a) AIDS, syphilis, cholera (b) HIV, malaria, trichomoniasis (c) Gonorrhoea, hepatitis-B, chlamydiasis (d) Hepatitis-B, haemophilia, AIDS 4. The technique called Gamete Intra Fallopian Transfer (GIFT) is recommended for those females (a) who cannot produce an ovum (b) who cannot retain the foetus inside uterus (c) whose cervical canal is too narrow to allow passage for the sperms (d) who cannot provide suitable environment for fertilisation. 5. Cu ions released from copper-releasing intra uterine devices (IUDs) (a) make uterus unsuitable for fertilisation (b) decrease phagocytosis of sperms (c) suppress sperm motility (d) prevent ovulation. 6. The status of the foetus for genetic counselling can be determined by (a) foetoscopy (b) amniocentesis (c) aminoacidopathy (d) ultrasound imaging.

(a) Identify A, B, C, D and E in the given figure. (b) Briefly describe the part labelled as D. (c) Name the enzyme present in labelled part B. chAPTer-4 : rePrODucTIVe heALTh

multiple choice Questions 1. IUDs which are used by females (a) are implanted under the skin and they release progestogen and estrogen (b) act as spermicidal jellies (c) release copper ions in the uterus having spermicidal effects (d) block the entry of sperms into vagina. 2. Vasectomy (a) prevents the production of sperms in the testes

7. Which of the following pairs is not correctly matched ? (a) Gonorrhoea - Treponema pallidum (b) Genital Warts - Human papilloma virus (c) Chlamydiasis - Chlamydia trachomatis (d) Scabies - Sarcoptes scabiei 8. Diaphragms are contraceptive devices used by the females. Choose the correct option from the statements given below. (i) They are introduced into the uterus. (ii) They are placed to cover the cervical region. (iii) They act as physical barriers for sperm entry. (iv) They act as spermicidal agents. (a) (i) and (ii) (b) (i) and (iii) (c) (ii) and (iii) (d) (iii) and (iv) 9. Which two of the following statements are incorrect regarding in vitro fertilisation? (i) In this method, ova from the wife/donor female and sperms from the husband/donor male are induced to form zygote in the uterus. MT BIOLOGY

TODAY | JANUARY ‘16

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(ii) If the embryo is having 2 blastomeres, it is transferred into the uterus. (iii) If the embryo is with more than 8 blastomeres, it is transferred into the uterus. (iv) The baby thus produced is called test tube baby. (a) (iii) and (iv) (b) (i) and (ii) (c) (ii) and (iii) (d) (i) and (iv) 10. Oral contraceptive pills prevents pregnancy by (a) killing the ovum (b) blocking fertilisation (c) preventing ovulation (d) suppressing sperm motility.

True or False 11. Immigration is the movement of individuals out of a place or country which results in the decrease in population. 12. Amniocentesis is a foetal sex determination and disorder test based on the chromosomal pattern in the cells of amniotic fluid surrounding the developing embryo. 13. Natality rate decreases population size and population density. 14. Exponential growth shows S-shaped or sigmoid growth curve whereas logistic growth shows J-shaped growth curve. 15. Vasectomy is a sterilisation technique for males in which two vasa deferentia are cut and tied up. 16. Population growth rate is indicated by the annual average growth rate and doubling time, it can never be negative. 17. Oral contraceptive pills contain either progestin alone or a combination of progestogen and oestrogen. 18. In females, ovulation is induced by clomiphene citrate. 19. In zygote intra-Fallopian transfer technique, zygote or early embryo is transferred into the Fallopian tube. 20. In foetoscopy, a needle-thin tube containing a viewing scope is inserted into the uterus for direct view of the foetus.

match The columns 21. Match Column I with Column II. Column I Column II

38

A. Non-medicated IUD

(i)

B. Chancroid

(ii) Male condom

C. Genital warts

(iii) Lippes loop

D. Nirodh

(iv) Female condom

E.

(v) Haemophilus ducreyi

Femidom MT BIOLOGY

Human papilloma virus

TODAY | JANUARY ‘16

22. Match Column I with Column II. (There can be more than one match for items in Column I) Column I Column II A. Hormone releasing IUDs (i) Amoebiasis B. Bacterial STDs (ii) i-pill C. Combined pills (iii) Unwanted 72 D. Protozoan STDs (iv) Progestasert E. Emergency contraceptives (v) Trichomoniasis (vi) Syphilis (vii) LNG-20 (viii) Mala D (ix) Gonorrhoea (x) Mala N

Passage Based Questions 23.(A) Complete the given passage with appropriate words or phrases. AIDS is a sexually transmitted (i) disease, caused by (ii) . The patient gets immune deficiency because AIDS pathogen attacks helper (iii) . It can be diagnosed by (iv) and (v) test. Pathogen of AIDS is transmitted via blood and (vi) . Although there is no cure of AIDS, yet certain drugs like (vii) and (viii) can prolong the life of patient. (B) Read the given passage and correct the errors, wherever present. In test tube baby technique, i.e., advanced reproductive technology, the fusion of ovum and sperm is done inside the body of woman, to form a zygote which is allowed to divide to form embryo. This embryo is implanted in vagina where it develops into a foetus (test tube baby). In this technique zygote is allowed to divide and form 16 blastomeres. The proembryo thus formed is transferred into the uterus. If the embryo is having more blastomeres, it is transferred into the Fallopian tube.

Assertion & reason In each of the following questions, a statement of Assertion (A) is given and a corresponding statement of Reason (R) is given just below it. Of the statements, mark the correct answer as : (a) if both A and R are true and R is the correct explanation of A (b) if both A and R are true but R is not the correct explanation of A (c) if A is true but R is false (d) if both A and R are false. 24. Assertion : Genital warts caused by human papilloma virus is a sexually transmitted disease.

Reason : Genital warts spreads through sexual intercourse with carriers of the viruses of this disease. 25. Assertion : Population growth rate is indicated by the annual average growth rate and the doubling time. Reason : It depends on birth rate and age-sex ratio only. 26. Assertion : Mortality rate is the number of births per one thousand individuals per year. Reason : Mortality rate increases population size and population density. 27. Assertion : Oral contraceptive pills are not recommended for women with a history of disorders of blood clotting. Reason : Oral contraceptive pills increase the risk of intravascular clotting.

E A B C

D

(a) Identify A, B, C, D and E in the given figure. (b) Briefly describe the procedure given in the figure. 30. Refer to the given figure and answer the following questions. B

28. Assertion : Immigration results in the increase in population. Reason : Immigration is the movement of individuals out of an area.

A C D

Figure Based Questions 29. Refer to the given figure and answer the following questions.

E

(a) Identify A, B, C, D and E in the given figure. (b) Briefly explain the method given in the figure.

U N S C R A MB L E

ME

Unscramble the letters using the given clues. Scrambled letters 1. 2. 3. 4.

NPERSAIMTOI TNSPCEIAE RTOXIPHMCOI JTCONNOI

5. 6.

NRTAKEI LTAORY

7. 8. 9. 10.

PYMIORMETHANU HNCELIS CLSNIPGI GSYONNSGEIE

Clues

Words

Release of sperms from seminiferous tubules. Enzyme used for clearing of juice in bottled juices. Mode of nutrition shown by Euglena. Arrangement of vascular bundle in which xylem and phloem are present together in the same bundle on the same radius. Water insoluble fibrous protein. Scientist who experimentally proved semi-conservative DNA replication in Vicia faba. Cancer treatment involving the use of interleukin-2. Pioneer species of xerarch. Step of post transcriptional modification. Development of plants from unfertilised cells of female gametophyte and ovules in tissue culture.

................................. ................................. ................................. .................................

................................. ................................. ................................. ................................. ................................. .................................

Readers can send their responses at [email protected] or post us with complete address by 25th of every month to win exciting prizes. Winners’ name will be published in next issue. MT BIOLOGY

TODAY | JANUARY ‘16

39

sOLuTIOns CHAPTER-1 : REPRODUCTION IN ORGANISMS

1. 6.

(c) (d)

2. 7.

3. 8.

(b) (d)

(a) (c)

4. 9.

(b) (b)

or inside the body of the organism. ‘C’ represents embryogenesis, which is the development of the embryo from the zygote. During embryogenesis, zygote undergoes mitotic cell division and cell differentiation. Cell division increases the number of cells in the developing embryo while cell differentiation helps to form specialised tissues and organs to form an organism.

5. (c) 10. (a)

11. True 12. False : Sexual reproduction involves formation of the male and female gametes. 13. True

14. True

15. False : In monoecious plant, both male and female flowers are present on the same plant. 16. True

30. (a) A – Zoospores of Chlamydomonas B – Conidia of Penicillium (b) Figures A and B represent asexual reproductive structures-zoospores of Chalamydomonas and conidia of Penicillium respectively. Zoospores are special kind of motile and flagellated spores produced inside the zoosporangia. They are generally naked i.e., without cell wall. The flagella help to swim in aquatic habitat for proper dispersal. Conidia are non-motile spores produced singly or in chains by constriction at the tip of lateral side of special hyphal branches, called conidiophores. They are produced exogenously, dispersed by wind and germinate directly by giving out germ tubes.

17. False : Endogamy involves the fusion of male and female gametes of the same parent. 18. True 19. False : In arrhenotoky type of parthenogenesis, only males are produced by parthenogenesis. 20. False : In viviparous animals, the zygote develops into a young one inside the body of the female organism. 21. A-(iii), B-(v), C-(i), D-(ii), E-(iv) 22. A-(iii, vii), B-(i, ix), C-(ii, x), D-(iv, viii), E-(v, vi) 23.(A) (i) zygote (ii) fertilisation (iii) stamens (iv) pistil (v) embryo (vi) seeds (vii) ovary (viii) pericarp (B) The process of formation of male and female gametes is called sporogenesis gametogenesis. Gametes are diploid haploid cells. In some algae, the two gametes are similar in appearance and are called anisogametes isogametes/ homogametes. In most of asexually sexually reproducing organisms the gametes are of morphologically dissimilar types, hence, they are known as isogametes anisogametes/ heterogametes. In anisogametes the male gamete is called the egg antherozoid/sperm and the female gamete is known as the antherozoid ovum/egg. 24. (a) 25. (c) 26. (d) 27. (c) 28. (a) 29. (a) A – Gametogenesis B – Fertilisation C – Embryogenesis (b) The given figure is the schematic representation of sexual reproduction. ‘A’ represents gametogenesis, the formation of two types of gametes - sperm (male gamete) and ovum (female gamete). Gametes are haploid cells. ‘B’ represents fertilisation, which is a complete and permanent fusion of two gametes from different parents or from the same parent to form a diploid zygote. It occurs either in external medium 40

MT BIOLOGY

TODAY | JANUARY ‘16

CHAPTER-2 : SExUAL REPRODUCTION IN FLOwERING PLANTS

1. 6.

(a) (c)

2. 7.

(b) (c)

3. 8.

(c) (b)

4. 9.

(a) (b)

5. (c) 10. (c)

11. False : Epicotyl is the part of embryonal axis in between plumule and cotyledonary node. 12. True 13. False : Xenogamy is transfer of pollen grains from anther to the stigma of a different plant. 14. True

15. True

16. False : Intine made up of cellulose and pectin. 17. True 18. False : Innermost wall layer of microsporangium is tapetum, it nourishes the developing pollen grain. 19. True

20. True

21. A-(iii), B-(iv), C-(i), D-(ii), E-(v) 22. A-(ii, v), B-(i, iv), C-(iii,ix), D-(vii, x), E-(vi, viii) 23.(A) (i)

(B)

embryo sac

(ii) haploid

(iii) nucellus

(iv) Polygonum (v) 8 (vi) 7 (vii) 3 (viii) 3 (ix) central Seed and fruit formation are stimulated by the act of pollination fertilisation. In angiosperms this process produces two structures - a haploid diploid zygote and a

diploid triploid endosperm cell. The zygote endosperm gives rise to a nutritive tissue and zygote forms the embryo. With the growth of embryo the peripheral central part of the nutritive tissue is eaten up. Nutritive tissue in turn crushes the micropyle nucellus. 24. (c)

25. (b)

26. (a)

29. (a) A – Scutellum C – Epiblast

27. (b)

28. (d)

B – Coleoptile D – Coleorrhiza

(b) The given figure is L.S. of an embryo of a plant belonging to grass family. B represents coleoptile and represents coleorrhiza. Coleoptile is a foliar structure that encloses the epicotyl bearing shoot apex and leaf primordia. It protects the plumule during emergence from soil. Coleorrhiza is a sheath encapsulating both radicle and root cap. It does not protect the radicle during its passage into the soil. (c) Epiblast (labelled as C), represents rudiments of second cotyledon. 30. (a) A – Epidermis C – Middle layers

(c) Labelled part D represents tapetum. It has a number of functions, which are as follows: (i) It provides nourishment to the developing microspore mother cells and pollen grains. (ii) It produces lipid rich Ubisch granules containing sporopollenin for exine formation, pollenkitt in case of entomophilous pollen grains, special proteins for the pollen grains to recognise compatibility and hormone IAA. (iii) It secretes enzymes like callase which is responsible for the degradation of callose wall present around pollen tetrad. CHAPTER-3 : HUMAN REPRODUCTION

(c) (a)

11. True

2. 7.

(c) (c)

3. 8.

16. False : Chorion is composed of trophoblast present towards the outerside and somatopleuric extraembryonic mesoderm present on inner side. 17. True

(b) (d)

4. 9.

(c) (d)

5. (d) 10. (c)

12. True

13. False : Spermatogenesis is the process of formation of sperms which includes formation of spermatids and formation of spermatozoa from spermatids. 14. False : During embryonic development, a solid ball-like structure which looks like a little mulberry is known as morula.

18. True

19. False : Vasa efferentia carries spermatozoa from the rete testis to the epididymis. 20. True 21. A-(iv), B-(ii), C-(i), D-(iii), E-(v) 22. A-(iii, v), B-(i, iv), C-(ii,vii), D-(vi, x), E-(viii, ix) 23.(A) (i) zona pellucida (ii) block (iii) sperms (iv) acrosome (v) cytoplasm (vi) meiotic (vii) secondary oocyte (B)

The mature ovum or a female gamete is tubular spherical in shape. The human ovum is said to be mesolecithal alecithal. Its cytoplasm is called acroplasm ooplasm containing mitochondria large nucleus, termed as mitochondrial germinal vesicle. There are many no centrioles in the ovum. The cytoplasm is enveloped by the plasma membrane and very large small vesicles called cortical granules are present below it. A wide narrow perivitelline space is present inside outside the plasma membrane.

24.

(c)

B – Endothecium D – Tapetum

(b) Endothecium (labelled part B) is known as fibrous layer. Endothecial cells develop fibrous thickenings of a-cellulose on the inner and radial walls and become dead. Because of the presence of these fibrous thickenings this layer is known as fibrous layer.

1. 6.

15. True

25. (b)

26. (a)

27. (d)

28. (c)

29. (a) A – Graafian follicle B – Tertiary follicle with antrum C – Ovum D – Corpus luteum E – Primary follicle F – Corpus albicans (b) The given figure is diagrammatic section view of mammalian ovary. Labelled part A represents Graafian follicle which secrete oestrogens mainly estradiol. It stimulate proliferation of the endometrium of the uterine wall. (c) Labelled part D represents corpus luteum. It secretes progesterone which stimulates the uterine glands to produce increased amount of watery mucus. It is also essential for maintenance of the endometrium. Such an endometrium is necessary for implantation of the fertilised ovum and other events of pregnancy. 30. (a) A – Plasma membrane C – Neck E – Tail

B – Acrosome D – Middle piece

(b) The given figure is the structure of a sperm. Labelled part D represents middle piece of human sperm. It contains the mitochondria coiled around the axial filament which is called as mitochondrial spiral. It provides energy for the movement of tail that facilitate MT BIOLOGY

TODAY | JANUARY ‘16

41

sperm motility essential for fertilisation. So, it is also known as the ‘power house of the sperm’. (c) The labelled part B represents acrosome which contains hyaluronidase and various proteolytic enzymes collectively known as spermlysins that helps in fertilising the ovum. CHAPTER-4 : REPRODUCTIvE HEALTH

1. (c) 2. (c) 3. (c) 4. (a) 5. (c) 6. (b) 7. (a) 8. (c) 9. (b) 10. (c) 11. False : Immigration is the movement of individuals into a place or country which results in the increase in population. 12. True 13. False : Natality rate increases population size and population density. 14. False : Exponential growth shows J-shaped growth curve whereas logistic growth shows S-shaped or sigmoid growth curve. 15. True 16. False : Population growth rate can be negative. 17. True 18. True 19. True 20. True 21. A-(iii), B-(v), C-(i), D-(ii), E-(iv) 22. A-(iv, vii), B-(vi, ix), C-(viii,x), D-(i, v), E-(ii,iii) 23.(A) (i) viral (ii) Human immunodeficiency virus (HIV) (iii) T-lymphocytes (iv) ELISA (Enzyme-linked Immunosorbent Assay) (v) Western Blotting (vi) Semen (vii) Azidothymidine / Zidovudine (viii) Dibanosine (B)

In test tube baby technique, i.e., advanced assisted reproductive technology, the fusion of ovum and sperm is done inside outside the body of woman, to form a zygote which is allowed to divide to form an embryo. This embryo

is implanted in vagina uterus where it develops into a foetus (test tube baby). In this technique zygote is allowed to divide to form 16 8 blastomeres. The proembryo thus formed is transferred into the uterus Fallopian tube. If the embryo is having more blastomeres, it is transferred into the Fallopian tube uterus. 24. (a) 25. (c) 26. (d) 27. (a) 28. (c) 29. (a) A – Placenta B – Uterine wall C – Amniotic fluid D – Cells shed by growing foetus E – Syringe with needle withdraws a small amount of fluid and cells. (b) The given figure represents the procedure of amnio centesis in which amniotic fluid containing cells from the skin of the foetus and other sources are withdrawn by using a special surgical syringe with needle. These cells are cultured and are used to determine chromosomal abnormalities such as Down’s syndrome, Klinefelter’s syndrome and metabolic disorders such as phenylketonuria; sickle cell anaemia of the foetus. Unfortunately, it is being misused to kill the normal female foetus. Therefore, it is legally banned for the determination of sex to avoid female foeticide. 30. (a) A – Ovary B – Uterus C – Cervix D – Vagina E – Fimbriae (b) The given figure represents tubectomy, a permanent sterilisation method of birth control in females. In this method small part of the Fallopian tube is removed or tied up through a small cut in the abdomen or through vagina. This is very effective method of birth control with very poor reversibility. 

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YIELD FACTS

Class XI

–

2 –

– – –

K.CET

J&K

–

1 2

Kerala

–

1

3 –

1 1

–

1

1

1

–

AIIMS

MT BIOLOGY

AMU

2

– – – –

–

2

2014

5

2013

3

2012

2

2011

AIPMT/NEET

Important characterIstIcs of monerans

• Monerans are basically unicellular (monos-single) prokaryotes and contain the most primitive of living forms. • They are varied in their nutrition—saprotrophic, parasitic, chemoautotrophic, photoautotrophic and symbiotic. The photoautotrophs include both aerobes and anaerobes. • The cells are microscopic (0.1 to a few microns in length). • Cell wall is generally present. It contains peptidoglycan and polysaccharides other than cellulose. • Cells have one envelope type of organisation, i.e., the whole protoplast is covered by plasma membrane but internal compartmentalisation is absent. • Genetic material is not organised into a nucleus. • DNA is naked, i.e., it is not associated with histone proteins. DNA lies coiled inside the cytoplasm and is known as nucleoid. It is equivalent to a single chromosome. • All membrane bound cell organelles are absent, e.g., mitochondria, lysosomes, spherosomes, Golgi bodies, plastids, etc. • The flagella, if present, are single stranded instead of being 11 stranded in eukaryotes. They are formed of protein called flagellin.

Analysis of various PMTs from 2011-2015

• Monera is a kingdom of prokaryotes. Therefore, it is also known as prokaryota. It includes the most primitive forms of life which developed from an early stock known as progenote. Being the earliest forms of life, monerans are adapted to all types of habitats. • Monerans have very little morphological differentiation. Therefore, it is very difficult to distinguish groups, subgroups, genera and species on the basis of structural and morphological characters alone. Many other characters are taken into consideration while classifying monerans e.g, biochemical, physiological and ecological characters. Molecular homology is being increasingly used in delimiting different taxa.

2015

Monerans

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43

• Mitotic spindle is absent. • Gametes are absent. Gene recombination has been discovered in certain cases. Otherwise reproduction is by asexual methods. • Some of the monerans have the ability to perform nitrogen fixation.

classIfIcatIon of monerans

• There are two major groups of monerans, Archaebacteria and Eubacteria. • Archaebacteria include ancient and primitive forms of bacteria. Based on the occurrence they can be, methanogens, halophiles and thermoacidophiles. • Eubacteria include true bacteria. They are of two types, bacteria and cyanobacteria. Rickettsiae, actinomycetes, mycoplasmas, etc., are various groups included in eubacteria.

archaebacterIa • This is simplest and most primitive group of bacteria. The cell wall of these bacteria is made of polysaccharides and proteins (peptidoglycans and muramic acid are absent in cell wall). • Further branched chain lipids are present in plasma membrane of archaebacteria, due to which these can face extremes of conditions of temperature and pH. • Three main types of archaebacteria are: (i) Methanogens: These are strict anaerobic bacteria and mainly occur in muddy areas and also in stomach of cattle (Methanobacterium), where cellulose is fermented by microbes. • These are responsible for methane gas (CH4) formation in biogas plants, because they have capacity to produce CH4 from CO2 or formic acid (HCOOH) (e.g., Methanobacterium, Methanococcus). (ii) Salt lover archaebacteria or halophiles: These bacteria occur in extreme saline or salty conditions (upto 35% of salt or NaCl in culture medium) (e.g., Halobacterium, Halococcus). • A purple pigmented membrane containing bacteriorhodopsin is developed in sunlight in these bacteria, which utilises light energy for metabolic activities (different from photosynthesis). (iii) Thermoacidophiles: These are the bacteria which are found in hot sulphur springs (upto 80°C). These are aerobic bacteria, which have the capacity to oxidise sulphur to H2SO4 at high temperature and high acidity (i.e., pH 2.0), hence given the name thermoacidophiles, i.e., temperature and acid loving. • Some of these bacteria are able to reduce sulphur to H2S under anaerobic conditions (e.g., Thermoplasma, Thermoproteus). 44

MT BIOLOGY

TODAY | JANUARY ‘16

• Archaebacteria are considered to be the `oldest of living fossils’.

bacterIa

• The bacteria are microscopic, unicellular, true chlorophyllfree prokaryotes which reproduce by binary fission. • They may occur singly or in aggregations to form colonies. In bacterial colonies, the individual cells are functionally independent. They are physiologically and biochemically diverse. • Bacteria possess rigid cell walls. Some are motile, whereas others are not.

Distribution and habitat

• Bacteria are cosmopolitan in distribution and are ubiquitous (everywhere). They occur in water, soil, air, animals, plants, in snow (upto – 190ºC) and also in hot water streams. They are found floating in the atmosphere mostly as “wanderers” on dust particles, up to height of several thousand feet, except just after heavy rains or snow storms when the air is generally free of them. • They are abundant on the surface of the human body and are present in large number in the intestinal tract and on all the mucous membranes. Unlike many higher organisms, bacteria have no natural death. • Under the three-domain system of taxonomy, introduced by Carl Woese (1977), which reflects the evolutionary history of life, the organisms found in kingdom Monera have been divided into two domains–Archaea and Bacteria (with Eukarya as the third domain). Furthermore, the taxon Monera is paraphyletic (does not include all descendants of their most recent common ancestor), as Archaea and Eukarya are more closely related to each other than either is to bacteria.

types of bacteria

• On the basis of shapes bacteria have been divided into six types: (i) Cocci : These are spherical or ellipsoidal in shape and are of 6 types : – Monococci : occur singly. – Diplococci : occur in pairs. – Tetracocci : occur in groups of 4. – Streptococci : occur in chains. – Sarcinae : occur in cubical forms of 8 or multiple of 8. – Staphylococci : occur in clusters like grapes. (ii) Bacilli : These are rod-shaped and are of following types: – Palisade bacilli : occur like a stack. – Diplobacilli : occur in pairs. – Streptobacilli : occur in chains.

(iii) Spirilla : These are spiral or helical in shape, e.g., Spirillum, Spirochaete. (iv) Vibrios : These are comma shaped bacteria, e.g., Vibrio cholerae. (v) Stalked : The bacterium possesses a stalk, e.g., Caulobacter. (vi) Budding : The bacterium is swollen at places, e.g., Rhodomicrobium.

Tetracoccus Sarcina Monococcus Staphylococcus Diplococcus Streptococcus Bacillus

(i) Monotrichous : When single flagellum occurs at one end only, e.g., Pseudomonas, Thiobacillus, Vibrio cholerae, Xanthomonas citri. (ii) Lophotrichous : When a group of flagella is present at one end only, e.g., Spirillum volutans. (iii) Amphitrichous : When single or group of flagella is present at both the ends, e.g., Nitrosomonas. (iv) Peritrichous : When flagella are present all over the surface of bacteria, e.g., E. coli, Salmonella, Proteus vulgaris. (v) Atrichous : When flagella are absent, e.g., Pasteurella pestis, Lactobacillus.

Diplobacillus

Palisade bacillus Streptobacillus Spirillum Vibrio Stalked Budded Fig.: Various forms of bacteria

structure of bacterial cell

• The structure of the bacterial cell can be broadly divided as follows : – Structure external to the cell wall. – Structure of the cell wall. – Structure internal to the cell wall. • The structures that are present external to the cell wall are glycocalyx or capsule, flagella, fimbriae and pili. The structures internal to the cell wall include plasma membrane, mesosome, cytoplasm, etc.

Glycocalyx • It is a sticky, gelatinous material that collects outside the cell wall to form an additional surface layer. • When this layer is firmly attached to the surface of the cell, it is called a capsule. If it is loosely distributed around the cell, the glycocalyx is called a slime layer. Presence or absence of capsule is genetically fixed. • Capsule is made of polysaccharides and amino acids. • Glycocalyx helps in (i) prevention of desiccation, (ii) protection from phagocytes, toxic chemicals, drugs, viruses, etc., (iii) attachment, (iv) immunogenicity, (v) virulence, etc. • Capsulated bacteria forming smooth colonies are called S-type bacteria. These are highly virulent. Noncapsulated bacteria forming rough colonies are called R-type bacteria. Flagella • Flagellum is the organ of motility in bacteria. Bacteria are of the following types on the basis of flagellation :

• Each flagellum is 4-5mm in length and arises from a basal granule called blepharoplast. Flagella is made up of flagellin protein. • Bacterial flagellum has three basic parts – filament, hook and basal body. It is made up of one or three a-helical strands. The basal body bears ring like swellings in the region of plasma membrane and cell wall. • There are two pairs of rings in Gram –ve bacteria and only a single pair of rings in Gram +ve bacteria. Hook is curved tubular structure which connects the filament with the basal body. It is the thickest part of flagellum. • Filament is long tubular structure which causes turbulence in the liquid medium.

Hook L-ring P-ring Rod S-ring M-ring

Filament Cell wall

Fig.: Lower region of flagellum of a gram negative bacterium

Pili and fimbriae • Many Gram-negative bacteria possess a number of hairlike structures that are shorter, straighter and thinner than flagella and are used for the attachment rather than for MT BIOLOGY

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CONCEPT

MAP

FLORAL MORPHOLOGY

GYNOECIUM Central, female reproductive part which develops from thalamus and consists of carpels (megasporophylls). l Each carpel consist of– stigma (the tip which receives pollen), style (elongated structure connecting stigma and ovary), ovary (lower swollen part containing ovules). l On the basis of number of carpels present, it can be moncarpellary (one carpel only) or multicarpellary (many carpels) which can be apocarpous (carpels free e.g., Ranunculus) or syncarpous (carpels fused e.g., Petunia). l On the basis of number of locules (chamber) present in the ovary, it can be unilocular (pea), bilocular (mustard), trilocular (Asparagus), tetralocular (Ocimum), pentalocular (China rose) or multilocular (Althaea). l

l The stamens may be equal or unequal in length. When there is two long and two short stamens, the condition is called didynamous, e.g., Ocimum. When out of six stamens, four are longer in inner whorls and two in outer whorl are shorter, the condition is called tetradynamous, e.g., mustard. l Dehiscence of anthers to expose the pollen grains can be longitudinal (long slits appear lengthwise e.g., mustard), transverse (breadthwise slits, e.g., Malva), porous (pores appear at the tip e.g., Solanum or base e.g., Cassia), valvular (split at several places by lifting of surface layers, e.g., Barberry), irregular (e.g., Najas). l Longitudinal dehiscence may be laterorse (slits on sides), introrse (slits towards the inner side or centre of the flower), extrorse (slits lie towards the outer side of flower).

PLACENTATION Arrangement of placenta (which bear ovules) on the ovary wall which can be : (i)Marginal : One or two longitudinal alternate rows of ovules along the ventral suture in unilocular ovary, e.g., pea, Cassia etc. (ii)Parietal : Ovules on walls of bi–multicarpellary but unilocular ovary e.g., Argemone. (iii) Axile : In multicarpellary, syncarpous, multilocular gynoecium; margins fuse at the centre of the ovary to form an axis which bears ovule e.g., Solanum. (iv)Free central : Unilocular ovary with ovules borne on central axis e.g., Dianthus. (v)Basal : Ovary unilocular with a single ovule at its base, e.g., sunflower. (vi)Superficial : Multicarpellary, syncarpous gynoecium bears a large number of ovules that are borne on the walls of loculi without specific order, e.g., Nymphaea.

A

flower is a highly condensed and modified shoot. It contains reproductive organs of the flowering plants, which develop fruits and seeds. There are four types of floral organs viz. sepals, petals, stamens and carpel or pistil. A flower having all the four types of floral organs is known as complete flower e.g., cotton. If one or more of the floral organs are absent it is called incomplete flower e.g., cucurbits. A flower having both the essential organs i.e., stamens and carpels is called hermaphrodite or bisexual flower, e.g., China rose, whereas a flower having only one of the two essential organs is known as unisexual flower e.g., mulberry. Flowers having only stamens are called staminate flowers and those having only carpels are called pistillate flowers. On the basis of symmetry flower can be actinomorphic (two equal halves in any plane), zygomorphic (two equal halves in one plane), or asymmetrical.

COROLLA

ANDROECIUM l Third and male whorl of the flower made up of stamens (microsporophylls) which consist of filament (lower stalk-like part which may be absent in some), anther (upper swollen part usually having two lobes or theca i.e., bithecous or in some monothecous, e.g., Althaea) and connective (sterile band which connects two anther lobes). In Salvia, connective forms a long curved structure, its one end has a fertile anther lobe and other has a sterile anther lobe. Stamens may be shorter than other whorls (inserted) or may protrude out of the flower (exserted). l On the basis of attachment to the filament, anthers can be adnate (filament runs along the back of the anther or becomes continuous with the connective, e.g., Ranunculus), basifixed (filament fixed at anther its base, e.g., Datura), dorsifixed (filament attached to back and anther immobile, e.g., Passiflora), versatile (filament attached to back and the anther can swing freely, e.g., grasses). l The cohesion between the stamens may be monadelphous (all the filaments united into a single bundle, anthers free, e.g., China rose), diadelphous (filaments united in two bundles, anthers free, e.g., pea), polyadelphous (filaments united into more than two bundles, anthers free, e.g., castor), syngenesious (anthers united into a bundle, filaments free, e.g., sunflower), synandrous (anthers as well as filaments united throughout the length, e.g., Colocasia). The free stamens are called polyandrous. l On the basis of adhesion of stamens to flower, it can be epiphyllous (attached to perianth, e.g., Asphodelus), epipetalous (attached to petals, e.g., Datura), gynandrous (attached to gynoecium, e.g., Calotropis).

l Second whorl inner to calyx made up of petals

which protects the inner whorls and attracts insects for pollination. Corolla may be polypetalous (petals free) or gamopetalous (petals fused). l Polypetalous corolla may be cruciform (four clawed or unguiculate petals arranged cross wise e.g., mustard), caryophyllaceous (five unguiculate or clawed petals with limbs placed at right angles, e.g., Dianthus), rosaceous (five or more sessile or shortly clawed petals with limbs spread regularly outwards, e.g., rose), campanulate or bellshaped (e.g., Physalis), papilionaceous (five unequal or irregular petals viz. 1 standard or vexillum – posterior largest–, 2 wings or alae –lateral, smaller– and 2 anterior petals fused together to form keel or carina). l Gamopetalous corolla may be campanulate (bell-shaped or inverted cup shaped e.g., Campanula), urceolate (urn-shaped e.g., Bryophyllum), tubular (tube-like or cyclindrical e.g., disc floret of sunflower), infundibuliform (funnel shaped e.g., Petunia), rotate (corolla with short tube having limbs placed transversely like a saucer or the spokes of a wheel, e.g., Solanum nigrum), salver shaped or hypocrateriform (tubular corolla with spreading lobes, e.g., Clerodendrum), bilabiate (bilipped corolla with gaping, wide open mouth, e.g., Ocimum), personate (bilipped corolla with closed lips, e.g., Antirrhinum), ligulate or strap-shaped (short and narrow tube-like corolla with upper part flattened like a strap, e.g., ray floret of sunflower), spurred (one or more petals drawn out like a beak or spur, e.g., Larkspur).

l

AESTIVATION

Stigma Style Ovary

Arrangement of petals (or sepals) in a flower bud with respect to members of the same whorls which can be open (margins of adjacent petals sufficiently apart from each other), valvate (margins of the adjacent petals lie close, without overlapping, e.g., mustard), twisted or contorted (one margin of a petal overlaps the margin of an adjacent petal (external) and the other margin is overlapped (internal) by the margin of adjacent petal, e.g., China rose), imbricate (one petal external, one internal; and of the remaining three petals one margin is overlapped, other overlapping, e.g., Cassia), quincuncial (special type of imbricate aestivation in which two petals external, two internal and in one petal one margin is overlapped, one is overlapping, e.g., calyx of Cucurbita maxima), vexillary (posterior petal overlapping the two lateral petals, the latter overlapping the two anterior petals, e.g., pea). l

Pollens

Anther Filament

Ovule

THALAMUS (Torus/Receptacle) l Broadened or swollen part of the flower which lies at the tip of the pedicel and bears floral organs. l In most flowers the thalamus is condensed but in some, one or more internodes elongate viz. anthophore (internode between calyx and corolla e.g., Dianthus), androphore or gonophore (internode between corolla and androecium, e.g., Passiflora), gynophore (internode between androecium and gynoecium, e.g., Capparis), gynandrophore or androgynophore (both androphore and gynophore present, e.g., Gynandropsis pentaphylla), carpophore (the thalamus in between the two carpels elongates and after bifurcation protrudes out of the two carpels, e.g., Coriandrum).

On the basis of relative position of floral organs on thalamus flower may be epigynous (ovary inferior, p l a ce d b e l ow o t h e r w h o r l s, e. g. , g u ava ) , hypogynous (ovary superior, e.g., China rose), or perigynous (ovary half superior or half inferior and thalamus may be disc e.g., pea, cup e.g., Prunus or flask e.g., rose shaped).

l

CALYX Outermost whorl made up of sepals which are usually green but sometimes coloured (i.e., petalloid). They protect the inner whorls and carry out photosynthesis when green. l The sepals may be free (polysepalous) or fused(gamosepalous). They can be caducous (fall just at the time of opening of bud, e.g., poppy), deciduous (attached till the flower withers, e.g., mustard), persistent (remain attached to the fruit, e.g., tomato). l Sepals can be modified to form pappus (hairy structure which helps in dispersal e.g., sunflower), leafy petalloid (large leaf like coloured structure, e.g., Mussaenda), spinous (persistent and modified into spines, e.g., Trapa), spurred (drawn out into beak or spur, e.g., Larkspur), hooded (modified into a hood, cover ing the whole flower, e.g., Aconitum) or bilabiate (twolipped, e.g., Salvia). l

BRACTS Specialised leaves from the axil of which flower arise. They can be foliaceous (leaf-like e.g., Adhatoda), petaloid (like petals, e.g., Bougainvillea), scaly (membranous, small e.g., sunflower), spathy (large, boat-shaped bract enclosing an inflorescence, e.g., banana, maize), glumes (small, dry, scaly as in spikelet of Poaceae ). l There are one or more whorls of bracts found at the base of calyx which form epicalyx in most members of Malvaceae, e.g., China rose. Sometimes, bracts are in one or more whorls around and below the entire inflorescence, e.g., coriander and are called involucre. l

PEDICEL OR STALK l Lower internode of flower. A flower with pedicel is called pedicellate and one without it, is sessile. It may bear bracteoles along with the bracts.

motility. These structures, which consist of a protein called pilin, are divided into two types, fimbriae and pili. • Pili are longer, fewer and thicker tubular outgrowths which develop in response to F+ or fertility factor in Gram –ve bacteria. So they are also called sex pili. They help in

attaching to recipient cell and forming conjugation tube. • Fimbriae are formed in large numbers. There are 300-400 of them per cell. Diameter is 3-10 nm and length is 0.5 – 1.5 mm. They help in attaching bacteria to solid surfaces or host tissues.

Table : Differences between prokaryotic and eukaryotic flagella Prokaryotic flagella

Eukaryotic flagella

(i)

They are single stranded.

They are 11-stranded.

(ii)

A covering membranous sheath is absent.

Flagella are covered by sheath derived from plasmalemma.

(iii)

The size is smaller.

The size is larger.

(iv)

They are narrower.

They are thicker.

(v)

Each flagellum has three parts—basal body, hook and filament.

There are two parts, basal body and shaft.

(vi)

Basal body bears rings.

Basal body bears rootlets.

(vii)

They are formed of protein flagellin.

The strands are formed of protein tubulin.

(viii)

They perform rotatory movements.

They perform lashing or undulatory movements.

Cell wall • Underlying the capsule and external to the cytoplasmic membrane is the cell wall which provides rigidity and shape to the bacterial cell. • The most important function of the cell wall is to protect the cell contents from external stresses and from lysis resulting from osmotic pressure. • Periplasmic space appears between plasma membrane and cell wall. • Cell wall is made of polysaccharides, proteins and lipids. • On the basis of differential staining technique called Gram

staining technique developed by Christian Gram in 1884, bacteria can be divided into two large groups : Gram + ve and Gram – ve bacteria. • In the cell wall of Gram +ve bacteria, both horizontal and vertical peptide linkages are present, due to which mesh is dense and hence the stain does not come out. Further outer layer of cell wall of Gram +ve bacteria is made of teichoic acid. In the cell wall of Gram –ve bacteria, either horizontal or vertical peptide linkages are present, due to which mesh is loose and hence stain comes out. Further outermost layer of cell wall of Gram –ve bacteria is made of lipopolysaccharides.

Teichoic acid

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• One of the unique components of cell wall of bacteria is peptidoglycan or mucopeptide or murein (made of mucopolysaccharide + polypeptide). In peptidoglycan, NAG (N-acetyl glucosamine) and NAM (N-acetyl muramic acid) are joined by short peptide chains or cross bridges of amino acids. The cell walls of Gram +ve bacteria contain 60–90% peptidoglycan whereas cell walls of Gram –ve bacteria contain about 10% peptidoglycan. • Cell wall of Gram –ve bacteria is thin (8-12 nm) and hard

and is not destroyed by penicillin, whereas cell wall of Gram +ve bacteria is thick (20-80 nm) and is destroyed by penicillin. Further, cell wall of Gram –ve bacteria is less homogenous, more complex and multilayered. Lipids (including phospholipids, lipopolysaccharides and lipoproteins) make up 80-85% of the total cell wall. The cell wall of Gram +ve bacteria is more homogenous and single layered and amorphous. Lipids are almost absent. Presence of lipopolysaccharides in cell wall of Gram –ve bacteria makes them pathogenic.

Table : Differences between Gram +ve and Gram–ve bacteria Gram +ve bacteria

Gram –ve bacteria

(i)

They remain coloured blue or purple with Gram stain The bacteria do not retain stain when washed with absolute even after washing with absolute alcohol or acetone. alcohol.

(ii)

The wall is single layered. Outer membrane is absent. The wall is two layered. Outer membrane is present.

(iii)

The thickness of the wall is 20-80 nm.

It is 8-12 nm.

(iv)

The lipid content of the wall is quite low.

The lipid content of the wall is 20-30%.

(v)

The wall is straight.

The wall is wavy and comes in contact with plasmalemma only at few places.

(vi)

Murein or mucopeptide content is 60-90%.

It is 10%.

(vii)

Porins are absent.

Porins or hydrophilic channels occur in outer membrane.

(viii)

Cell wall contains teichoic acids.

Teichoic acids are absent.

(ix)

Examples: Staphylococcus, Streptococcus, Pneumococcus, Bacillus, Clostridium,Mycobacterium, Streptomyces.

Examples : Salmonella, E.coli, Pseudomonas, Vibrio and Azotobacter.

Plasma membrane • Bacterial plasma membrane or plasmalemma has a structure similar to that of a typical membrane. It is made of a phospholipid bilayer with proteins of various types (extrinsic, integral, transmembrane). However, typical sterols (e.g., cholesterol) are absent. Instead pentacyclic sterols, called hopanoids, are found in some bacteria. Hopanoids stabilise the membrane. • Bacterial membrane is metabolically active as it takes part in respiration, synthesis of lipids and cell wall components. Mesosome • It is a circular to villiform membranous structure which develops as an ingrowth from the plasma membrane. • It is less prominent in Gram –ve bacteria but is quite conspicuous in Gram +ve bacteria. • Mesosome is of two types, septal and lateral. Septal mesosome connects nucleoid with plasma membrane. It takes part in the replication of nucleoid. Lateral mesosome is

not connected with nucleoid. It contains respiratory enzymes and is therefore, often called chondrioid.

Cytoplasm • It is crystallo-colloidal complex that forms the protoplasm excluding its nucleoid. • Cytoplasm is granular due to presence of a large number of ribosomes. • Membrane bound cell organelles as found in eukaryotes are absent. However, all biochemical pathways are found in prokaryotic cells. • Cytoplasmic streaming is absent. • Sap vacuoles are absent. Instead gas vacuoles are present. • Various structures present in cytoplasm are as follows: (i) Ribosomes • The ribosomes are 70S in nature. Each ribosome has two subunits, larger 50S and smaller 30S. MT BIOLOGY

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• Ribosomes take part in protein synthesis. Free or matrix ribosomes synthesise proteins for intracellular use while fixed ribosomes synthesise proteins for transport to outside.

(ii) Chromatophores • In certain photosynthetic bacteria, most of the cytoplasm is occupied by single-membraned, vesicular structures which are the extensions of the cytoplasmic membrane. These are called chromatophores and contain photosynthetic pigments along with the enzymes and electron carriers for the photosynthetic phosphorylation.

Glycogen RNA

Lipid globule

Cell wall Mesosome

Respiratory enzymes Pilus (Fimbria) Filament Hook

Ribosome

(iii) Inclusion bodies • They are non-living structures present in the cytoplasm. The inclusion bodies may occur freely inside the cytoplasm (e.g., cyanophycean granules, volutin or phosphate granules, glycogen granules) or covered by 2-4 nm thick non-lipid, non-unit protein membrane (e.g., gas vacuoles, carboxysomes, sulphur granules, PHB granules). • On the basis of their nature, the inclusion bodies are of 3 types — gas vacuoles, inorganic inclusions and food reserves. (a) Gas vacuoles • They are gas storing vacuoles found in cyanobacteria, purple and green bacteria and a few other planktonic forms. Gas vacuoles protect the bacteria from harmful radiations. They also constitute buoyancy regulation mechanism for their proper positioning in water during day time as per requirement of photosynthesis. (b) Inorganic inclusions • Several types of inorganic granules occur in bacteria. They include volutin granules, sulphur granules, iron granules, magnetite granules, etc. Because of the ability to pick up different colours with basic dyes, they are called metachromatic granules.

Polyribosome

Nuclear body (Nucleoid)

Mucilage Cytoplasm Plasma membrane

Basal body Flagellum

Fig.: Cell structure under electron microscope (Plasmid and volutin granules not shown).

(c) Food reserves • Cyanobacteria have cyanophycean starch or a-granules, b-granules of lipid globules and cyanophycin or protein granules. In bacteria, starch is replaced by glycogen. Neutral fats are absent. Instead polybetahydroxybutyrate or PBH granules are present. Nucleoid • Bacteria lack nuclei and do not possess the complex chromosomes characteristic of eukaryotes. Instead their genes are encoded within a single double-stranded ring of DNA which is present in the centre of cell not surrounded by any membrane (so DNA is considered naked). This primitive type of nucleus is known as nucleoid or genophore or incipient nucleus. Plasmids • Many bacterial cells also possess small, independently replicating circles of DNA called plasmids. Plasmids contain only a few genes, usually not essential for the cell’s survival. They are best thought of as an excised portion of the bacterial chromosome.

1.

Why do most antibiotics selectively kill bacterial cells only and not human cells?

2.

The bacteria which are surrounded by capsule (encapsulated bacteria) are more pathogenic (or virulent) than the bacteria which are not surrounded by capsule. Why is this so?

3.

Differentiate between the cell wall composition of Gram +ve and Gram–ve bacteria.

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• Plasmids which can get associated temporarily with nucleoid are known as episomes. Plasmids are used as vectors in genetic engineering.

Rhodopseudomonas palustris) and green sulphur bacteria (e.g., Chlorobium limicola). The pigments occur in the membranes of thylakoids.

• Plasmids carry non-vital genes which may or may not be useful to bacteria. Plasmids which do not confer any useful trait to the cells are called cryptic plasmids. Three types of useful plasmids are F-plasmids, R-plasmids and Colplasmids. (i) F-Plasmids : They are plasmids which contain genes for conjugation or fertility. An F-plasmid is, therefore, also called fertility factor or F-factor. A bacterium having F-plasmid is called male or donor bacterium. It develops sex pili for conjugating with female or recipient bacterium which is devoid of F-factor. F-plasmid not only pass into recipient bacterium but can also help in transfer of nuclear genes from F+ to F– bacterium. (ii) R-Plasmids : They are plasmids which carry genes for resistance against common antibiotics like chloramphenicol, tetracycline, streptomycin and sulphonamide. Pathogenic bacteria having R-plasmids are very difficult to treat. (iii) Col-Plasmids : They are also called colicinogenic factors. They produce toxins called colicins or bacteriocin which are lethal to other enterobacteria. Col-plasmid can also get transferred from one bacterium to another just like F-plasmid or R-plasmid.

• No oxygen is evolved in bacterial photosynthesis. Such type of photosynthesis is known as anoxygenic photosynthesis.

Nutrition in bacteria • Bacteria show both autotrophic and heterotrophic nutrition. Autotrophic nutrition consists of manufacture of organic materials from inorganic raw materials with the help of energy obtained from outside sources. • It is of two types, chemosynthesis and photosynthesis.The bacteria performing these modes of nutrition are respectively called chemoautotrophs and photoautotrophs. • Heterotrophic nutrition involves the obtaining of readymade organic nutrients from outside sources. It is of further three types —saprotrophic, symbiotic and parasitic.

Photoautotrophic bacteria • The bacteria possess photosynthetic pigments of two types,bacteriochlorophyll and bacterioviridin (chlorobium chlorophyll). The two types of pigments respectively occur in purple bacteria (e.g., Thiopedia rosea,

• Water is not used as a source of reducing power. Instead, hydrogen is obtained either directly (some purple bacteria) or from various types of inorganic and organic compounds, e.g., H2S (green bacteria), aliphatic compounds (purple nonsulphur bacteria).

Chemoautotrophic bacteria • They are bacteria which are able to manufacture their organic food from inorganic raw materials with the help of energy derived from exergonic chemical reactions involving oxidation of an inorganic substance present in the external medium. • Nitrifying bacteria (e.g., Nitrosomonas and Nitrosococcus) are the chemoautotrophic bacteria which obtain energy by oxidising ammonia to nitrite. + – NH4 + 2O2 → NO2 + 2H2O + Energy Nitrocystis and Nitrobacter oxidise nitrites to nitrates. – 2 NO2– + O2 → 2 NO3 + Energy • Sulphur oxidising bacteria e.g., Beggiatoa, a colourless sulphur bacterium, oxidises hydrogen sulphide to sulphur in order to obtain energy for chemosynthesis. 2H2S + O2

Beggiatoa

2S + 2H2O + Energy

Thiobacillus thioxidans, another sulphur bacterium, oxidises sulphur to sulphate state. 2S + 2H2O + 3O2

Thiobacillus thioxidans

2H2SO4 + Energy

Saprotrophic bacteria • They are free living bacteria which obtain their food from organic remains, e.g., corpses, animal excreta, fallen leaves, vegetables, fruits, meat, jams, jellies, bread and other products of plant and animal origin. Symbiotic bacteria • These bacteria live in mutually beneficial association with other organisms. Enteric bacterium Escherichia coli, lives as a symbiont in human intestine. Parasitic bacteria

• These bacteria live in contact with other living beings for obtaining nourishment or special organic compounds required for growth (growth factors) e.g., Vibrio cholerae. MT BIOLOGY

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Bacterial respiration

• According to the mode of respiration, bacteria can be aerobic or anaerobic. Each of them is further of two types, obligate and facultative. (i) Obligate aerobes – They are bacteria which can respire only aerobically. They generally get killed under anaerobic conditions, e.g., Bacillus subtilis. (ii) Facultative anaerobes – They are bacteria which generally respire aerobically but switch over to anaerobic mode of respiration if oxygen becomes deficient, e.g., halophiles.

(iv) Facultative aerobes – They are bacteria which respire anaerobically under normal conditions but can respire aerobically when oxygen is available. Most of the photosynthetic bacteria (e.g., Rhodopseudomonas) belong to this group.

Reproduction in bacteria • Three types of reproduction are known in bacteria. These are vegetative reproduction, asexual reproduction and sexual reproduction.

Vegetative reproduction • It is of following types: (i) Budding: It is a rare method of reproduction and is reported in Bigidi bacterium-bifidus. (ii) Binary fission: It is the most common type of reproduction in bacteria during favourable conditions. Here bacterial cell divides by a constriction into two halves. At the same time nuclear material elongates and divides into two equal halves probably helped by mesosomes. • Binary fission of bacteria and other prokaryotes does not involve the formation of a spindle. In this regard, it is similar to amitosis. • A new mesosome develops and gets attached to the daughter chromosome. Membrane grows between the two mesosomes to push the daughter nuclear bodies or chromosomes to the opposite side. • The cytoplasm now undergoes a transverse centripetal constriction in the middle to form two daughter protoplasts, each having a nuclear body. • Under favourable conditions of binary fission, bacterial cell divides into two after every 20 minutes and at this rate in 24 hours period, a single bacterial cell produces 4 × 1021 bacteria, but only about 10% of them survive. 52

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Bacterial growth curve • Bacteria show four major phases of growth in a fresh nutrient rich medium – lag phase, log phase (logarithmic or exponential phase), stationary phase and decline phase (death phase). • When a fresh medium is inoculated with a given number of cells, and the population growth is monitored over a period of time, plotting the data will yield a typical bacterial growth curve. Stationary Log or exponential phase growth phase

Log of numbers of bacteria

(iii) Obligate anaerobes – The bacteria of this category respire only anaerobically. They generally get killed under aerobic conditions, e.g., Clostridium botulinum.

Fig.: Binary fission in a bacterial cell

Death or decline phase

Lag phase 0

5 Time (hr)

10

Asexual reproduction • It occurs by following means : (i) Endospore formation : During unfavourable condition, highly resistant single spore is formed inside the bacterial cell, which is known as endospore. Endospore means spore inside bacterial cell or cell inside cell. Endospore formation is more common in rod-shaped bacteria or bacillus forms. • Endospore is highly resistant to very high and very low temperature, strong chemicals and acids, etc., due to calcium, dipicolinic acid and peptidoglycan in cortex. When favourable conditions come, outer layers rupture and active bacterial cell comes out. So it is a method of perennation (i.e., to tide over unfavourable condition) also and some people say it “reproduction without multiplication”.

Exosporium Spore coat Cortex Plasma membrane Air Core wall Cytoplasm Nuclear body (Nucleoid) Fig.: Structure of an endospore

(ii) Conidia formation : Rarely in some filamentous forms of bacteria (Streptomyces), conidia are formed. (iii) Zoospores: Motile spores are formed in Rhizobium bacteria, but are rare in other bacteria.

Sexual reproduction • True sexual reproduction is absent in bacteria, but there occurs genetic recombination, i.e., bringing together of genetic material of two bacterial cells. There are 3 main methods of genetic recombination: – Transformation – Transduction – Conjugation (i) Transformation: Here genetic material of one bacterial cell goes into another bacterial cell by some unknown mechanism and it converts one type of bacterium into another type (Non-capsulated to capsulated form).

• This was first studied by Griffith (1928) in Diplococcus pneumoniae and hence is known as Griffith effect. Later on it was studied in detail by Avery, McCarty and McLeod. (ii) Transduction : In this method, genetic material of one bacterial cell goes to other bacterial cell by agency of bacteriophages or phages (viruses, infecting bacteria). • Transduction was first of all reported in Salmonella typhimurium by Zinder and Lederberg (1952). • The process also occurs in E.coli and a number of other hosts. A virus may pick up gene of the host in place of its own gene during its multiplication in the host cell. Such a virus is never virulent. It passes over the gene of the previous host to the new host. Transducing viruses may carry the same genes (restricted transduction) or different genes (generalised transduction) at different times. (iii) Conjugation: Here cell to cell union occurs between two bacterial cells and genetic material (DNA) of one bacterial cell goes to another cell lengthwise through conjugation tube which is formed by sex pili. • Conjugation was first reported by Lederberg and Tatum (1946) in E. coli bacteria.

Pilus

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and pickles caused by saprotrophic bacteria.

Saprotrophic bacteria act as nature’s scavengers.

Used for the formation of manure and gobar gas.

• Conjugation occurs between donor cell and recipient cell. Donor cell is having sex pili and F-factor whereas recipient cell is lacking both. • In donor cell, F-factor may unite with main genome or nuclear DNA and this donor cell is called Hfr-donor cell (High Frequency donor cell) and here transfer of DNA is rapid.

cyaNoBacteRia • Although cyanobacteria are true prokaryotes, but their photosynthetic system closely resembles with that of eukaryotes because they have chlorophyll a and photosystem II and they carry out oxygenic photosynthesis. Like the red algae, cyanobacteria use phycobiliproteins as accessory pigments. Photosynthetic pigments and electron transport chain components are located in thylakoid membranes lined with particles called phycobilisomes, which contain phycobilin pigments, particularly phycocyanin and transfer energy to photosystem II. • CO2 is fixed through C-3 cycle or Calvin cycle and the reserve carbohydrate is glycogen. Sometimes they store extra nitrogen as polymers of arginine or aspartic acid in cyanophycin granules. 54

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• Cyanobacteria do not have a fully functional Krebs’ cycle or citric acid cycle as they lack enzyme a-ketoglutarate dehydrogenase. Pentose phosphate pathway (PPP) plays a central role in their carbohydrate metabolism. • Most of the cyanobacteria are obligate photolithoautotrophs but some can grow slowly in dark as chemoheterotrophs by oxidising glucose and other sugars. They show considerable metabolic flexibility. • G + C content of this group ranges from 35 to 71%.

Diving bell spiders, found in Northern and Central Europe and Northern Asia, are the only spiders able to spend entire life underwater. They do this by spinning a ‘bell’ of air using silk and catching oxygen with her leg hairs. The silk bell allows oxygen to diffuse in and CO2 to diffuse out just as gills do. As a result, this spider has to make only one trip out of the water per day.

• Cyanobacteria vary greatly in their shape and appearance. They range about 1-10mm in diameter and may be unicellular, exist as colonies of many shapes, or form filaments called trichomes. • Cyanobacteria have typical prokaryotic cell structures and a normal Gram-negative type cell wall. • They often use gas vesicles to move vertically in water and many filamentous species have gliding motility. • Cyanobacteria lack flagella but marine genus Synechococcus are able to move at the rate of 25mm/ second by some unknown mechanism.

/Chromatophore

• Cyanobacteria reproduce by binary fission, budding, fragmentation and multiple fission. Fragmentation of filamentous cyanobacteria can generate small, motile filaments called hormogonia. Some species develop akinetes. • Many filamentous or trichome-forming cyanobacteria fix atmospheric nitrogen by means of special thick-walled cells called heterocysts. About 5–10% cells of a trichome develop into heterocysts, which obtain nutrients from adjacent vegetative cells and contribute fixed nitrogen in the form of amino acid glutamine. • There are five orders of cyanobacteria—Chroococcales (Chamaesiphon, Gleocapsa, Synechococcus); Pleurocapsales (Pleurocapsa, Dermocarpa); Oscillatoriales (Lyngbya, Spirulina, Oscillatoria); Nostocales (Anabaena, Nostoc, Cylindrospermum, Scytonema); Stigonematales (Stigonema, Fischerella).

• Cyanobacteria are highly tolerant of environmental extremes and are present in almost all aquatic and terrestrial environments. Thermophilic species may grow at temperatures upto 75°C in alkaline hot springs. Some unicellular forms grow in fissures of desert rocks. In eutrophic warm ponds and lakes, surface cyanobacteria like Anabaena and Anacystis can reproduce rapidly to form blooms. The death of bloom microorganisms releases organic matter, which stimulates the growth of chemoheterotrophic bacteria which deplete the available oxygen and this kills fish and other organisms. • Oscillatoria, a cyanobacterium is highly pollution resistant and grows in fresh water with high organic matter, acts as indicator of water pollution. • Cyanobacteria successfully develop symbiotic relations with other organisms. These are photosynthetic partners in many lichens. Further, these are symbionts with protozoa, liverworts, mosses, gymnosperms and angiosperms. • Nostoc is a colonial cyanobacterium that is popularly called moonspit, fallen star or star jelly. It also forms symbiotic association with Anthoceros, cycad roots, Gunnera stems and Trifolium roots. • The cyanobacterium Spirulina is cultivated for human consumption and has a dry weight protein content of about 70%. This is common in saline lakes and is sold as a nutritional food supplement in most health food stores in USA.

Heterocyst • It is a large-sized pale coloured thick-walled cell which occurs in terminal, intercalary or lateral position in filamentous cyanobacteria, e.g., Nostoc. The thick wall is impermeable to oxygen but permeable to nitrogen. Mucilage sheath is absent. Photosystem II is absent. Thylakoids lack phycobilisomes. Therefore, photosynthesis is absent but cyclic photophosphorylation occurs. Heterocyst is dependent for its nourishment on adjacent vegetative cells. It has enzyme nitrogenase. Heterocyst is specialised to perform nitrogen fixation.

RicKettSiae • Rickettsiae are Gram negative obligate pleomorphic but intracellular parasites which are resident of or are transmissable by arthropods. • They are intermediate between true bacteria and viruses. • Rickettsiae require exogenous factors for growth. • Cell wall is like typical bacterial wall. ATP synthesis is absent, but ADP is exchanged with host cell ATP. • They have size 0.3-0.5 mm which is smaller than true bacteria but have a long generation time. MT BIOLOGY

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• Flagella, pili and capsule are absent. • Reproduction occurs by binary fission. • The natural habitat of rickettsiae is in the cells of arthropod gut. • They often become pathogenic in mammals and humans where they cause typhus group of fever spread by droplet method, lice, ticks, fleas, etc., e.g., Coxiella burnetti (Q fever), Rickettsia rickettsiae (Rocky mountain spotted fever spread by ticks), R. typhi (Endemic typhus), R. prowazeckii (epidemic typhus), Rochalimaea quintana (Trench fever).

actiNoMyceteS • Actinomycetes are mycelial (aseptate branched filaments) bacteria which form radiating colonies in culture. Because of this, actinomycetes were formerly called ray fungi. • Mycelial form is reduced in Mycobacterium and Corynebacterium. Mycelia have a diameter of 1mm or less. Wall contains mycolic acid (fatty acid), lipid and wax. • Different modes of reproduction occur by conidia, sporangiospores and arthrospores or oidia and fragmentation. • Most of the actinomycetes are saprotrophic and constitute an important component of decomposers, e.g., Actinomyces, Streptomyces. A few are pathogenic in plants, animals and humans, e.g., Mycobacterium. In pathogenic actinomycetes or Mycobacterium a derivative of mycolic acid called mycoside/cord factor is involved in causing disease. • A number of antibiotics are produced by actinomycetes, especially the genus Streptomyces (streptomycin, chloramphenicol, tetracyclines, terramycin, erythromycin, viomycin, novobiocin, nystatin). • Frankia produces root nodules in some non-legumes (e.g., Alnus) and takes part in nitrogen fixation.

MycoPLaSMa • Mycoplasmas or mollicutes are the smallest known prokaryotic organisms, characterised by the absence of cell wall. • These organisms were discovered in 1898 by Nocard and Roux in the pleural fluid of cattles suffering from pleuropneumonia and were, therefore, called pleuropneumonia like organisms (PPLO). • They also demonstrated that if healthy cattles were injected with these microorganisms, the symptoms of disease appear. 56

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• Borrel et al (1910) gave them the name Asterococcus. Later, Nowak (1929) placed them in the genus Mycoplasma. • Mycoplasma are now known to infect a large number of animals (e.g., dog, sheep, mice and even man) and plants (e.g., potato, corn, brinjal, etc). • In nature they occur in soil, sewage water and in plant and animal bodies. Besides, they have also been found in hot water springs. In the laboratory, they are common contaminants of cultures rich in organic matter. • As mycoplasma have no cell wall, hence have no definite shape, i.e., pleomorphic and thus are called jokers of microbiology.

Structure of mycoplasma • The structure of mycoplasma varies from species to species, e.g., in Mycoplasma mycoides, filamentous form and in Mycoplasma pneumoniae, coccus (rounded) form occurs. On outer side, there is tripartite (3-layered) cell membrane, made of lipoproteins as usual. • In stationary phase, mesosomes are also present on plasma membrane or cell membrane. Inner to cell membrane, matrix is present, which is mainly having double stranded, long, circular DNA, single stranded RNA (in both ribosomes and cytoplasm), ribosomes of 70 S type and many metabolites like proteins (enzymes) and fatty substances. There is 4% DNA and 8% RNA. Replicating disc Plasma membrane Ribosomes DNA RNA Protein particle Enzymes Granules Fig.: Ultrastructure of PPLO

Reproduction in mycoplasma • Reproduction in mycoplasma occurs by – Budding. – Fragmentation : Specially in filamentous forms. – Binary fission: Most common method of reproduction in mycoplasma is binary fission. • Bleb and infra bleb are peculiar structures which are formed at both ends during binary fission in mycoplasma and as soon as

binary fission is complete, these structures disappear, so the significance of bleb and infra bleb is not known.

Diseases caused by mycoplasma

• Many plant diseases caused by mycoplasma were earlier considered to be viral diseases. The symptoms of diseases caused by viruses and mycoplasma are similar and it is difficult to distinguish between them. Diseases caused by mycoplasma are generally transmitted through insects such

as leafhoppers, mites and flies. Some of the commonly known plant diseases are aster yellows, potato witche’s broom, mulberry dwarf, maize stunt, rice yellow dwarf, bunchy top of papaya, little leaf of brinjal, clover phyllody, etc. • Animal diseases like rheumatism, arthritis, several respiratory disorders and primary atypical pneumonia (PAP) are caused by mycoplasma. M. hominis and M. fermentans, cause infertility in human males.

4.

Why were cyanobacteria initially classified under Kingdom Plantae finally placed into Kingdom Monera?

5.

Why are mycoplasmas resistant to antibiotics that interfere with cell wall synthesis?

6.

What is the function of bacterial endospores?

1.

Which of the following is free living N2 fixing bacteria? (a) Rhizobium (b) Streptomyces (c) Nitrobacter (d) Azotobacter

2.

Read the given statements and select the correct option.

6.

The main difference in Gram +ve and Gram –ve bacteria resides in their (a) cell wall (b) cell membrane (c) cytoplasm (d) flagella.

Statement 1 : Peptidoglycan polysaccharides are one of the unique components of the bacterial cell wall. Statement 2 : The cell wall of Gram –ve bacterium contains teichoic acid. (a) Both statements 1 and 2 are true and statement 2 is the correct explanation of statement 1. (b) Both statements 1 and 2 are true but statement 2 is not the correct explanation of statement 1. (c) Statement 1 is true and statement 2 is false. (d) Both statements 1 and 2 are false.

7.

The bacterium (Clostridium botulinum) that causes botulism is (a) an obligate aerobe (b) a facultative anaerobe (c) an obligate anaerobe (d) a facultative aerobe.

8.

Peptidoglycan is a characteristic constituent of the cell wall of (a) bacteria and unicellular eukaryote (b) bacteria and cyanobacteria (c) archaebacteria and eukaryote (d) all members of monera and protists.

3.

Which organelle is called `Chondrioid’ in bacteria? (a) Mitochondria (b) Chromatophores (c) Pili (d) Mesosomes

9.

4.

When a group of flagella is present at one end only, bacteria are called (a) amphitrichous (b) lophotrichous (c) peritrichous (d) none of these

Monerans do not include (a) bacteria (b) cyanobacteria (c) archaebacteria (d) slime moulds.

10. Bacterial conjugation was first shown by (a) Robert Hooke (b) Lederberg and Tatum (c) Dickson and Jolly (d) Skoog.

5.

Which type of the bacteria are immunologically virulent? (a) R-type (b) S-type (c) Both R and S-type (d) None of these

11. Teichoic acid is found in the cell wall of (a) Gram +ve bacteria (b) Gram –ve bacteria (c) cyanobacteria (d) mycoplasma. MT BIOLOGY

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12. Mesosome in a bacterial cell is (a) plasmid (b) connection between two cells (c) plasma membrane infolded for respiration (d) none of the above 13. The characteristic cell wall material peptidoglycan has another covering of lipopolysaccharides. This specialised condition is found in (a) Gram +ve eubacteria (b) Gram-ve eubacteria (c) all eukaryotes (d) all fungi. 14. In the cell wall of Gram –ve bacteria (a)

both horizontal and vertical peptide linkages are present (b) only horizontal peptide linkages are present (c) only vertical peptide linkages are present (d) either horizontal or vertical peptide linkages are present. 15. Nitrosomonas converts (a) NH3 → Nitrite (b) N2 → NH3 (c) Nitrite → Nitrate (d) NH3 → N2. 16. Respiratory enzymes in bacteria are present in (a) mitochondria (b) Golgi complex (c) mesosome (d) endoplasmic reticulum.

17. In bacteria, the site for respiration is (a) episome (b) mesosome (c) cytoplasm (d) plasmid. 18. Bacterial flagella are mainly made up of (a) protein (b) amines (c) lipids (d) carbohydrates. 19. Cyanobacteria are (a) cyanophycean members which infect bacteria (b) virus which infect blue green algae (c) autotrophic prokaryotes with characteristic blue green pigments (d) bacteria which infect cyanophycean algae. 20. Monerans that are devoid of cell wall are (a) actinomycetes (b) cyanobacteria (c) mycoplasma (d) eubacteria. 21. Some hyperthermophilic organisms that grow in highly acidic habitats belong to the two groups (a) eubacteria and archaea (b) cyanobacteria and diatoms (c) protists and mosses (d) liverworts and yeasts. 22. Select the correct combination of the statements (i-iv) regarding the characteristics of certain organisms. (i) Methanogens are archaebacteria which produce methane in marshy areas. (ii) Nostoc is a filamentous blue-green alga which fixes atmospheric nitrogen. (iii) Chemosynthetic autotrophic bacteria synthesise cellulose from glucose. (iv) Mycoplasma lack a cell wall and can survive without oxygen. 58

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(a) (ii) and (iii) (b) (i),(ii) and (iii) (c) (ii), (iii) and (iv) (d) (i), (ii) and (iv) 23. What is a plasmid? (a) Bacterial linear dsDNA (b) Extrachromosomal linear RNA (c) Extrachromosomal circular dsDNA (d) Autonomously replicating circular RNA 24. Read the given statements and select the correct option. Statement 1 : Endospores in bacteria are formed during unfavourable conditions. Statement 2 : Endospores are highly resistant to adverse environmental conditions like extreme temperatures, strong acids, etc. (a) Both statements 1 and 2 are true and statement 2 is the correct explanation of statement 1. (b) Both statements 1 and 2 are true but statement 2 is not the correct explanation of statement 1. (c) Statement 1 is true and statement 2 is false. (d) Both statements 1 and 2 are false. 25. Which one of the following is not the characteristic feature of cyanobacteria? (a) They are always multicellular. (b) They may form colonies. (c) They form blooms in polluted water bodies. (d) They can fix atmospheric nitrogen. 26. Which one of the following organisms is not an eukaryote? (a) Paramecium caudatum (b) Escherichia coli (c) Euglena viridis (d) Amoeba proteus 27. In eubacteria, a cellular component that resembles eukaryotic cell is (a) plasma membrane (b) nucleus (c) ribosomes (d) cell wall. 28. Cell in some filamentous cyanobacteria which is specialised for nitrogen fixation is called (a) heterocyst (b) mesosome (c) volutin (d) phycobilisome. 29. Spherical bacteria called (i) are found in pairs called (ii) , or long chain-like clusters called (iii) , or grapelike aggregates called (iv) . Select the correct option for (i), (ii), (iii) and (iv). (a) bacilli diplobacilli streptobacilli staphylobacilli (b) sprillia sarcina tetracoccus diplococcus (c) cocci streptococci diplococci staphylococci (d) cocci diplococci streptococci staphylococci 30. Causal organisms of tuberculosis and leprosy belong to (a) mycoplasma (b) cyanobacteria (c) actinomycetes (d) archaebacteria.

ANSWER 1. 6. 11. 16. 21. 26.

(d) (a) (a) (c) (a) (b)

2. 7. 12. 17. 22. 27.

(c) (c) (c) (b) (d) (a)

3. 8. 13. 18. 23. 28.

(d) (b) (b) (a) (c) (a)

KEY 4. 9. 14. 19. 24. 29.

(b) (d) (d) (c) (a) (d)

5. 10. 15. 20. 25. 30.

(b) (b) (a) (c) (a) (c) 

Class XI

Animal Kingdom-IX class reptilia 2 1 – 6 J&K

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1

9 4

1 2

– 5

–

4

4

8

3

6 1

1 4

3 2

5

2014

4 8 3

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Kerala

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K.CET

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–

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2

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AIIMS

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AMU

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2012

•

4

•

breathing, cold-blooded, oviparous and tetrapodal vertebrates. Body bilaterally symmetrical and divisible into 4 regions-head, neck, trunk and tail. Limbs are of two pairs and pentadactyl. Digits bear horny claws. However, limbs are absent in few lizards and all snakes. Exoskeleton comprises of horny epidermal scales, shields, plates and scutes. Skin is dry, cornified and devoid of glands. Mouth terminal. Jaws bear simple conical teeth. In turtles teeth are replaced by horny beaks. Alimentary canal terminates into a cloacal aperture. Endoskeleton bony. Skull with one occipital condyle (monocondylic). A characteristic T-shaped interclavicle present. Heart usually three-chambered with a partly divided ventricle, four-chambered in crocodiles. Sinus venosus reduced. Two systemic arches present. Red blood corpuscles oval and nucleated.

2011

• Predominantly terrestrial, creeping or burrowing, mostly carnivorous, air-

AIPMT/NEET

General characters

Analysis of various PMTs from 2011-2015

on land. • The characters of reptiles are in fact a combination of characters that are found in fish and amphibians on one hand and in birds and mammals on the other. • The class name Reptilia refers to the mode of locomotion (L., repere or reptum, to creep or crawl), and the study of reptiles is called Herpetology (Gr., herpeton, reptiles). • Reptiles are abundant in the tropical regions. Very few are found in the colder parts of the temperate region and none in the Arctic and Antarctic regions.

2015

• Reptiles represent the first class of vertebrates fully adapted to live in dry places

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• Respiration by lungs throughout life. • Kidneys metanephric. Crocodiles are ammonotelic.

Turtles are ureotelic. Lizards and snakes are uricotelic.

•

• Brain with better development of cerebrum than in Amphibia. • • •

•

•

Twelve pairs of cranial nerves. Lateral line system absent. Jacobson’s organ present in the roof of buccal cavity. Most reptiles are carnivorous or insectivorous. Most tortoises are herbivorous. Sexes separate. Male usually with a muscular copulatory organ. Fertilisation internal. Mostly oviparous. Large yolky meroblastic eggs covered with leathery shells, always laid on land. Embryonic membranes (amnion, chorion, yolk sac and allantois) appear during development. No metamorphosis. Young ones resemble adults. Parental care usually absent.

• • •

•

from some primitive labyrinthodont Amphibia, in the beginning of Carboniferous period. The labyrinthodonts possessed characteristically folded or labyrinthine teeth. They flourished through Carboniferous and Permian periods before extinction in the Triassic. The earliest reptiles are called as stem reptiles. They belong to order Cotylosauria of the subclass Anapsida. These primitive or generalised reptiles had two common characteristics; the complete roofing of skull (anapsid condition), and the flattened plate-like pelvic girdle. From this generalised condition in the succeeding periods, arose several lines of radiation or specialisations, some leading to the great array of reptiles, both extinct as well as living, and others to birds and mammals.

classification • The Class Reptilia is divided into five subclasses on the

Origin of reptiles

basis of presence or absence of certain openings through the posterolateral or temporal region of the skull.

• It is generally agreed that primitive reptiles originated



Fish or porpoise like

Mammal-like



(dorsal)

 

One temporal fossa is present. Extinct. Turtle like

(ventral)

Heart three chambered.

Small to medium, elongated Fixed quadrate

Immovable quadrate

Heart is three chambered. tuatara

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Large-sized, tail laterally compressed

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Heart is three chambered. Male with an erectile, grooved penis O

Dinosaurs (ancient reptiles)

• Tyrannosaurus is an example of gigantic carnivorous

• The word ‘dinosaur’ is a blend of the Greek terms ‘deinos’

(meaning terrible) and ‘saurus’ (meaning lizard). Richard Owen coined the term dinosaur. • The dinosaurs were divided into two main types; one with a bird like pelvis and the other with reptilian pelvis. • They were subdivided into two orders : Saurischia (reptilelike dinosaurs) and Ornithischia (bird-like dinosaurs). • The early dinosaurs of Saurischia group were fast,

carnivorous, two legged forms.

dinosaur. It was about 15 m long and stood 6 m high. • Many Saurischia changed to a plant diet and became four legged forms. Brontosaurus, the largest of them weighed approximately 50 tons. • The dinosaurs of Ornithischia group were herbivorous. Although, some of them walked upright, the majority were four-legged. • Having lost their front teeth, they developed a stout, horny, bird-like beak. Iguanodon is an important example of this group.

Table : Important examples of Reptiles Scientific name

Common name

Important notes Cotylosauria

–

Seymouria

• • • •

Found in the lower Permian of Texas (Extinct). Lizard-like, 60 cm long. Thick body, pointed head, dorsally placed nostrils and a short tail. Structure intermediate between amphibians and early reptiles. Chelonia

Testudo

Tortoise

• • • •

Terrestrial form. Large in size, ovoid carapace. Head can be completely withdrawn into the shell. Herbivorous.

Chelone

Turtle

• • • •

Marine form. Heart shaped carapace. Fore and hind limbs are modified into paddles. Some turtles are flesh eaters.

Trionyx

Soft shelled turtle

• Smooth leathery shells without shields. • Snout forms short proboscis. • Clawed and webbed digits.

Chrysemys picta

Painted terrapin

• Colourful. • Feeds on insects.

Rhynchocephalia Sphenodon punctatum

Tuatara

• Living fossil, have primitive characters. • Median pineal or parietal or third eye. Widely roofed mouth. Three temporal bridges

in skull. Absence of copulatory organs in male. Insectivorous, nocturnal reptile with vertical pupil. Colour is dull olive green with yellow spots above and white below. Upper surface covered with granular scales and bears mid-dorsal frill of spines. Lacertilia (Lizards)

Hemidactylus

House wall lizard, Geckos

• • • •

It has power of autotomy and regeneration. Digits have adhesive pads that adhere by vacuum. Eyes lack movable lids and tongue is sticky and protrusible. Some geckos are vocal, making clicking and peeping sounds.

Draco

Flying dragon or flying lizard

• Small brilliantly coloured lizard with a very long tail and well developed limbs. • It has membranous parachute like fold of skin, (patagia), supported by ribs. These

are used for gliding.

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Phrynosoma

Horned toad or Desert lizard

• It has 2 enlarged horns on head and grotesque spines on body. • It shows desert adaptations. • It feeds on ants.

Chameleon

Chameleon

• It can change colour in order to blend with the surroundings (camouflage). • Insectivorous, can catch insect about 20cm away by eversible tongue. • Long and prehensile tail.

Heloderma

Gila monster

• Poisonous, venom glands and ‘fangs’ are in lower jaw. • Found in USA and Mexico. • Commonly called beaded lizard because resemblance of scales with beads.

Varanus

Monitor lizard, (Goh)

• Tongue long and protrusible. • The largest living lizard in the world is the Komodo dragon, Varanus komodoensis.

May reach a length of 3m and weigh 250 kg. Calotes

Garden lizard, (Girgit)

• Arboreal. • When excited, head and neck turn red and trunk becomes pale yellow.

Uromastix

Spiny-tailed lizard (Sanda)

• Oil is extracted from its fat bodies. • Oil is used for treatment of muscular pain.

Ophidia (Snakes) Poisonous Cobra

Naja naja

• Poisonous. • Can be recognised by presence of hood that bears spectacle mark. • Its venom is neurotoxic, attacks nerve centres and causes paralysis of respiratory

muscles. • Shows cannibalism, oviparous. • Naja bungarus , the king Cobra is the only snake in the world that builds a nest. It guards the nests. Bungarus

Krait

• Venom is neurotoxic. Quantity of poison injected is three times more than cobra.

Paralysis of trunk and limbs occur. • Its body has alternate broad black and yellow rings. • Nocturnal and true cannibals.

Viviparous. Head is triangular, flat and covered with scales. Large plates on ventral surface. Venom is haemotoxic.

Vipera

Viper

• • • •

Hydrophis

Sea snake

• Viviparous. • Head is small and shielded, tail is laterally compressed. • Venom is neurotoxic.

Crotalus

Rattle snake

• Viviparous. • Has rattle on tail.

Non-poisonous Ajgar

Python

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• • • • •

Oviparous. Huge and massive in size. Lives on trees in forests. Tail is short and prehensile. Diamond shaped brown and green spots on body. Kills the prey by coiling around and crushing and swallowing its prey.

Typhlops

Blind snake

• Small burrowing snake, looks like earthworm. • Tail is blunt. • Eyes are vestigial. Harmless and feeds on insect larvae and termites.

Ptyas

Rat snake, (Dhaman)

• Colour is olive above, whitish below. • Eyes are large. • Tail forms more than one-third of body. • Feeds on mammals, birds and frogs.

Dendrophis

Tree snake

• Body elongated, slender and compressed. • Head depressed, vertebral scales enlarged. • It is diurnal and feeds on lizards and frogs.

Eryx

Sand boa (double

• Tail is small, non prehensile, thick, gives false resemblance of head, hence the name

double headed snake.

headed snake)

• Feeds on rat, mice etc.

Crocodilia Crocodylus palustris

Indian fresh water crocodile

• Found in Asia, Central America, Africa, Malaya, Indonesia and North Australia. • Snout moderately long and pointed. • Body length around 8 metres. • Colour olive green with black spots or bands. • Aggressive, dangerous to man.

Alligator mississipiensis

American alligator

• Found in North America and China. • Less aggressive. • Snout short, broad and rounded. • Body length around 3 metres. • Colour steel grey.

Gavialis gangeticus

Gharial

• Found in India, Myanmar, Pakistan and Nepal. • Eats only fish because of narrow throat. • Snout very long and slender. • Body length around 6 metres. • Colour dark olive green.

Economic importance of reptiles

Reasons for success of reptiles on land

As food • Of all reptiles, turtles are most heavily exploited for human consumption. • Crocodiles, snakes and lizards are locally important food sources.

• Four factors have made reptiles true land animals

For pest control • Reptiles eat insects and rodents that are pests of crops. • Reptiles are also economically important for medicinal products, leather goods and pet trade.

independent of moist environment : − Horny scales which check loss of water. − Internal fertilisation as gametes cannot survive on land. − Shell around the egg to check desiccation. − Fluid-filled amnion around the embryo to provide aquatic environment for its development on land.

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some important facts • Mesozoic era is known as the golden age of reptiles. • Snake has both an exoskeleton as well as an endoskeleton. • Foramen of Panizzae is an aperture in the heart of lizards and crocodiles. It is located at the point where right and left aorta

cross each other and are in contact. • Study of lizards is known as saurology. • Cloacal respiration occurs in turtles. • Hemidactylus shows autotomy by breaking off its tail when threatened. • Chameleon is ovoviviparous lizard. • Heloderma suspectum is the only poisonous lizard of the world. • Study of snakes is called ophiology or serpentology. • Hoffkin’s Institute, Mumbai is well known for the production of anti-venom injections.

1. 2. 3.

Reptiles represents the first group of vertebrates fully adapted to live on land. Discuss some features that eventually lead to success of reptiles on land. Give a small note on origin of reptiles. Give some examples of poisonous and non-poisonous snakes.

ClAss AvEs • The Class Aves include birds. The birds are unique in having a

coat of feathers and in resting on the hindlimbs alone. • Birds exhibit great variety of colours and behaviours such as courtship, nest building, parental care and migration. • Birds are often described as “glorified reptiles” because of their resemblance with the reptiles.

General characters

• Body is covered by feathers. • Skin is dry and without glands except for the presence of

• • •

• The body is spindle-shaped and streamlined. It is

divisible into head, neck, trunk and tail. • Head is small and rounded. Neck is long, vertical and flexible.

Trunk is compact. Tail is short.

•

• The upper and lower jaws are prolonged and covered with

horny sheath modified into beak, which lacks teeth. • Beaks are adapted to many ways of feeding; seed-crushing,

fruit-scooping, flesh-tearing, nectar-sipping, wood-chiselling and so on. • There are two pairs of limbs. The forelimbs are modified into wings for flight. The wings are supplied energy by powerful flight, or breast muscles attached to a large sternum, or breast bone. • Sternum is large with a mid-ventral keel for attachment of flight muscles. • The hindlimbs or legs are large and variously adapted for perching, walking, hopping, wading or swimming. 64

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•

•

•

an oil or preen gland or uropygeal gland at the base of short tail or uropygium. The secretion of this gland is used for dressing the feathers. Oil gland is absent in flightless birds, parrots, pigeons, doves and woodpeckers. Sweat glands are absent. The endoskeleton is ossified, but light and strong. Many bones are fused to acquire strength. Endoskeleton is represented by (i) feathers (ii) scales on legs, similar to those of reptiles, (iii) claws on the toes (iv) sheaths on beaks. The feathers are highly modified reptilian scales. They conserve body heat, help in flight and provide colouration to the bird. Skull is monocondylic, i.e., has a single occipital condyle. The last 3 or 4 fused tail vertebrae form a structure called pygostyle. The forked bone furcula formed by the fusion of two clavicles and single interclavicle is called wish bone. Synsacrum is formed by the fusion of posterior thoracic, lumbar, sacral and anterior caudal vertebrae. Alimentary canal contains crop (modified oesophagus) for storing and softening of food and gizzard (grinding part of stomach, the other glandular part being proventriculus) for crushing it.

• Cloacal aperture is present. • Gall bladder is absent in some seed-eating birds

• The voice is produced by the vibrations of the tympaniform

membranes of syrinx as the air is forcibly expelled from the lungs during expiration.

(graminivorous) such as pigeons. • Respiration takes place only by lungs. The latter are spongy and inelastic and are associated with thin-walled air sacs. • Most of the birds have 9 major air sacs. They are named according to their location in the body such as interclavicular, cervical, anterior thoracic, posterior thoracic and abdominal. Air sacs are paired in origin but the two interclavicular air sacs fuse early in development. Larynx Syrinx

Bronchus Inter-clavicular air sac

Bronchus Right lung

Bird milk • Like mammals, the young ones of some birds are fed on

special secretions from parents.

• Unlike mammals, however, both sexes produce it. The •

Glottis Trachea Cervical air sac Clavicular air sac Extraclavicular air sac Humeral air sac in cavity of humerus Anterior thoracic air sac

• • • •

Posterior thoracic air sac

Left lung Abdominal air sac Fig.: Respiratory system of a bird

• The arrangement and presence of air sacs brings several

advantages in respiration : − At each breath lungs of birds are completely emptied. Residual air restricted to air sacs only. − Air of lungs is renewed twice at each breath. During inspiration much of air reaches directly into the air sacs through the secondary bronchi then back to the lungs through separate ducts and the recurrent bronchi.

• The heart is relatively large and fast beating for quick

• • •

• •

• •

• Voice box lies at the junction of the trachea and bronchi. It

is called syrinx (characteristic feature). The larynx (without cords) does not act as a sound box.

best known of these secretions is the “crop milk” that pigeons feed to squabs. The milk is produced by a sloughing of fluid-filled cells from the lining of the crop, a thin-walled, sac-like foodstorage chamber that projects outward from the bottom of the oesophagus. Crops are presumably a device for permitting birds to gather and store food rapidly, minimizing the time that they are exposed to predators. Crops tend to be especially well developed in pigeons and game birds. Crop milk is extremely nutritious. The pigeon milk which contains more protein and fat than does cow or human milk, is the exclusive food of the nestlings for several days after hatching, and both adults feed it to the squabs for more than two weeks.

•

supply of adequate amount of blood during flight. It is 4-chambered, having two auricles and two ventricles. There is neither sinus venosus nor truncus arteriosus. Only right aortic arch (systemic) persists in adults. Renal portal system is greatly reduced. Red blood corpuscles are oval, biconvex and nucleated. The brain is large with well developed optic lobes and cerebellum and reduced olfactory bulbs. There are 12 pairs of cranial nerves. The olfactory sacs open by internal nares into the buccal cavity. Sense of smell is usually poor. Eyes possess a comb-like structure or pecten. It is present in all birds except Kiwi. Pecten is well developed in diurnal birds than nocturnal. It helps in accommodation and nutrition of eye ball. It may cast a shadow on retina and thus helps in the perception of movements. It also regulates the fluid pressure in the eye. Birds have keen eyesight. Each ear consists of three parts : external, middle and internal. Pinnae are absent. Kidneys are metanephric and 3-lobed. Ureters open into cloaca. Excretory matter is chiefly uric acid (uricotelism). Urinary bladder is absent. Well marked sexual dimorphism is present. Testes are paired. Female has a single functional left ovary and oviduct. MT BIOLOGY

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• Fertilisation is internal. Males generally lack copulatory

organs. Copulation occurs by cloacal apposition. • All birds are oviparous. Eggs are large with much yolk

(marcolecithal) and hard, calcareous shell, and need incubation at a constant body temperature by the parents. • Ninety-five

percent monogamous.

of

bird

species

are

socially

• Development is direct. Embryonic membranes (amnion,

chorion, allantois, yolk sac) are formed as in reptiles.

keep themselves warm. Therefore, they must feed more often than most reptiles. • The birds show advancement over the reptiles in having: regulated body temperature; light insulating coat of feathers; aeration of blood in the lungs during both inspiration and expiration; complete separation of oxygenated and deoxygenated blood in the heart; highly developed brain; more efficient eyes and ears; and active life due to high rate of metabolism.

Classification

• Bursa fabricii is a lymphoid tissue attached to cloaca

of some young birds which takes part in formation of lymphocytes and probably it produces antibodies and protects against local infection but it atrophies in the adult before sexual maturity. It is also called cloacal thymus. • The birds are homoiotherms, and spend a lot of energy to

• Birds show less diversification than any other group of

vertebrate animals. About 9,000 living species of birds are known at present. • The Class Aves is divided into two subclasses: Archaeornithes and Neornithes. It is given in details in the following flow chart.

. J

J -

–

present.

, female has clitoris

Giant elephant bird

66

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, green parrot (Psittacula krameri, peafowl (Pavo cristatus), cuckoo (Cuculus canorus), Swan (Cygnus), White breasted kingfisher (Halcyon smyrnensis), hoopoe (Upupa epops), Pelicans (Pelecanus), Sand piper (Tringa glariola), gull (Larus), flamingo (Phonicopterus), saruus crane (Antegone antegone), common pariah kite (Milvus migrans), king vulture (Sarcogyps calvus), peregrine falcon (Falco peregrinus), eagle (Aquila), Indian swift (Micropodus).

Feathers

Barbs

• Feathers of bird are light, strong, elastic, waterproof and

show many colours due to presence of pigments. • Feathery exoskeleton is characteristic of bird. • Feathers are variously modified to serve different functions : − Due to light weight, impervious, flexible, durable and waterproof body covering, it protects the underlying tender skin from all kinds of mechanical, chemical, pathological and environmental injuries. − The feathers serve the most important function of retention of heat. − The feathers hold a considerable blanket of enveloping air around the body and add much to its buoyancy. − Feathers provide many secondary sexual characters to both sexes of most birds which help in recognition of sexes and sexual selection. − They are also used as natal covering in those birds that are born in an advanced state of development and as dense undercoat in many aquatic birds. − They are also used in the formation of nest.

Types of feather • Feathers are characteristic feature of birds since no other group of animal kingdom has ever developed them. Various types of feathers are: Quill (flight) feather • Quill feathers have a strong shaft (or rachis) and barbules with an interlocking arrangement. They are further classified into following types: − Remiges are the wing-quills used for flight. − Rectrices are tail-quills that act as a brake and help in steering the flight. − Covert cover the base of wing-quills. They are smaller in size and oppose the buoyancy of the air. Contour feathers (pennae) • Contour feathers form general covering of the body having poorly developed barbules. • Contour feathers provides a smooth surface to body, reduces drag or frictional resistance to motion through air, give shape by overlapping of the vanes and make a good heat conserving layer. Filoplumes • These are small, delicate and hair-like feathers sparsely distributed over the body. • Also known as space filling feathers. • Probably help keep the other feathers in their place.

Rachis (Shaft)

Rachis Vane

Calamus Barbules Calamus

Calamus Umbilicus

Fig. : A. Contour feather; B. Down feather or plumule; C. Structure of a typical flight feather (Remex)

Down feathers or plumules • It is without shaft and bear fluffy tuft of barbules. • In young one, down feathers, cover the body and are called as nestling down feathers. • Other types are Tactile feathers/vibrissae at the root of beak (in owl and nocturnal birds), ornamental plumes of many birds, bristles around the base of bill (rachis) of fly catchers, goat suckers etc, and powder down feathers which occur in many birds usually aggregated into patches, such as paired pectoral and pelvic yellowish patches on the skin of herons and sometimes in scattered tracts and tufts as in parrots, etc. • The arrangement or distribution of feathers on the body is called pterylosis. • In majority of birds, except penguins, the feathers are not uniformly distributed over the whole body but are arranged in distinct patches or tracts called pterylae. • The pterylae are followed by featherless areas or apteria.

Aerial or flight adaptations in birds • The following modifications are present in birds that help

them fly :− The spindle-shaped body of a bird is designed to

To easily remember the six hormones secreted by the anterior pituitary gland, the mnemonic “FLAT PiG” can be used as follows: F (sH) l (H) A (CTH) T (sH) P (rolactin) i G (H)

: : : : : : :

Follicle Stimulating Hormone Luteinizing Hormone Adrenocorticotropic Hormone Thyroid Stimulating Hormone Milk Stimulating Hormone ignore Growth Hormone MT BIOLOGY

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− − − − − − − −

offer minimum resistance to the wind and hence easily propelled through the air. Presence of feathers make the body streamlined and further helps its passing through the air by reducing friction to the minimum. Forelimbs are modified into wings, which help during flight. The conversion of forelimbs into wings is duly compensated by the presence of a bill or beak. Besides procurement of food, beak is also used for nest building. The flight muscles on the breast are greatly developed which help in flight. Most of the bones are pneumatic and filled with air instead of bone marrow. It makes the body light. Birds are warm blooded animals which is responsible for high temperature of the body (40°C - 46°C), a necessity for flight. Urinary bladder is absent. Excreta is passed out at once. These features help in reducing the weight of body. Presence of a single functional ovary on the left side in the female bird also leads to reduction of weight which is essential for flight.

Modes of flight • There are four chief kinds of flight in birds, and all the kinds may be used at different times by the same bird. Also, in all types of flight, the tail helps to support and balance the body, serving as a rudder. Gliding or skimming • The simplest and probably the most primitive mode of flight is gliding. • Birds hold their wings spread, motionless and glide for a considerable distance without flapping them. • Gliding flight can be readily observed in shore-birds coming in for a landing; in ducks, gulls and herons over water. soaring or sailing • It is the most remarkable and highly specialised mode of flight, illustrated by birds with a large wing-span, such as albatross, vulture, falcon, stork, crow, etc. • The bird, usually at a high level, describes great circles without any movement of wings. Flapping • It is the most common or ordinary mode of flight. All birds fly by flapping their wings up-and-down. Hovering • It is a peculiar variant of flapping flight. In hovering, found in humming birds, the body is kept vertical, while the bird remains poised in the air before a flower or above an object upon the ground, the tips of its wings apparently describes a figure of eight. 68

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Types of beaks in birds • Birds exhibit indefinite variations in shape, size and structure

•

•

•

•

•

•

•

• •

•

of beaks. The diversity of forms of beaks is related to the type of food eaten and manner of feeding. The most common types of beaks are: Seed-eating beak – Short, stout, peg-like and conical beaks are characteristic of small granivorous or seed-eating birds, such as sparrows, finches and cardinals. Cutting beaks – Birds such as crows, possess long and slender beaks with cutting edges which can be used variously. Fruit-eating beak – In parrots, the beak is sharp, massive, deeply hooked and extremely strong. It is well adapted for gnawing or breaking open hard seeds and nuts, which form their staple diet. Insectivorous beak – In swallows and swifts, the beak is small, wide and delicate to scoop-up their living insect prey while on wing. In hoopoe, the beak is long, slender and slightly curved and meant for turning the leaves or probing into the soil for insect grubs and pupae, etc. Wood-chiselling beak – Woodpeckers have elongated, straight and stout chisel-like beaks for drilling into the barks or wood for insect larvae or for nest construction. Tearing and piercing beak – Carrion-feeding and flesheating birds, such as vultures, hawks, eagles, owls, kites, etc., have short, pointed, sharp-edged and powerful, hooked beaks for tearing flesh which are operated by welldeveloped mandibular muscles. Mud-probing beak – Familiar examples of mud-probing beaks are found in snipe, stilt, sand-piper, lapwing, etc. Their beaks are extremely long and slender and are used as a probe for thrusting far down into water and mud in search of worms and larvae. Water and mud-straining beak – In ducks and geese the beak is broad and flat. Fish-catching beak – Storks, herons and kingfishers have long, powerful and sharply-pointed, spearing beaks to capture fish, frogs, tadpoles and similar aquatic animals. Flower-probing beak – The long, pointed and rapierlike probing beak of tropical humming birds dive down the corollas of flowers for sucking honey and insects.

Types of feet or claws in birds

• Cursorial or running feet – In running birds, the legs are

powerful and the number of toes is reduced. The hind toe may be elevated, reduced or absent. In bustards and ratites such as emu, rhea and cassowary, only 3 toes, directed forward are present. • Perching feet – The birds hold the twig or perch firmly by flexing their toes around it. The majority of birds belong to the category of perching birds or passers, such as sparrows, crows, bulbuls, robins, mynahs, etc. • Scratching feet – The feet of fowls, quails, pheasants,

•

•

• •

•

etc. are stout, with strongly-developed claws and well adapted for running as well as scratching the earth. Raptorial feet – Predatory or carnivorous birds, such as eagles, kites, vultures, owls, etc. have strongly taloned feet for striking and grasping their prey. The toes have strongly-developed, sharp and curved claws. Wading feet – The legs and toes are exceptionally long and slender in wading or marshy birds such as herons, snipes, jacana, lapwing, etc. These serve to walk over aquatic vegetation or marshes e.g., ducks, pelicans. Swimming feet – In swimming birds, the toes are webbed, partially or completely. Climbing feet – In parrots and woodpeckers the feet are used as grasping organs and especially adapted for climbing vertical surfaces. Clinging feet – In swifts, martinets and hummingbirds, all the four toes point forward and serve to cling.

Migration • It may be defined as regular and periodical movements

of birds between their summer and winter homes or it is a periodic swing from a breeding and nesting place to a feeding and resting place.

Kinds of migration latitudinal migration • The most familiar migrations are latitudinal that is, north to south and vice versa. • These are pronounced in the Northern Hemisphere, having larger land masses. • Birds move during summer over the temperate and subarctic regions of Northern Hemisphere, where there are facilities for feeding and nesting. • The birds return to the south for shelter during winter, when north is covered with ice and snow. • E.g., Some birds of Siberia visit the plains of Himalayas in India. longitudinal migration • Some birds make migrations that are longitudinal rather than latitudinal, that is, east to west and vice versa. • E.g., Starling moves from a breeding area in east Europe or Asia towards the Atlantic coast, to avoid the continental winter. Altitudinal migration • Wherever large mountains are found in temperate regions, the birds migrate regularly up and down their slopes, as the weather changes. • The birds pass the summer in the mountainous regions, but return to the lowlands in winter.

• It is merely a dispersal or short journey from the bleaker

slopes to the more protected valley and has been called altitudinal or vertical migration. • It occurs in the grebes and coots of Andes in Argentina.

seasonal migration • Field observers in temperate countries have grouped migrating birds according to seasons. • In Britain, swifts, swallows, nightingales and cuckoos are summer visitors, for they arrive in spring from the south, remain to breed and leave for the south in autumn. • Some birds like fieldfare, snow bunting and redwing are winter visitors, as they arrive in autumn, chiefly from the north, stay throughout the winter and fly northwards again in spring. • Some birds like snipes and sandpipers are the birds of passage, seen for a short time twice a year on their way to colder or warmer countries in spring and autumn.

Communication • Birds communicate using both visual and auditory signals.

•

•

• •

Signals can be interspecific (between species) and intraspecific (within species). Birds sometimes use plumage to assess and assert social dominance, to display breeding condition in sexually selected species, or to make threatening displays. Visual communication among birds may also involve ritualised displays, which have developed from non-signalling actions such as preening, the adjustments of feather position, pecking, or other behaviour. Bird calls and songs, which are produced in the syrinx, are the major means by which birds communicate. Calls are used for a variety of purposes, including mate attraction, evaluation of potential mates, bond formation, the claiming and maintenance of territories, the identification of other individuals (such as when parents look for chicks in colonies or when mates reunite at the start of breeding season), and the warning of other birds of potential predators, sometimes with specific information about the nature of the threat.

Parental care • At the time of their hatching, chicks may be helpless or

independent, depending on their species. • Helpless chicks are termed altricial, and tend to be born small, blind, immobile and naked; chicks that are mobile and feathered upon hatching are termed precocial. • Altricial chicks need thermoregulation and must be brooded for longer than precocial chicks. • Chicks at neither of these extremes can be semi-precocial or semi-altricial. MT BIOLOGY

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Table : Important examples of birds Scientific name

Common name

Important notes Flightless birds

African Ostrich (Shutarmurg)

Struthio

• Largest living flightless bird, prominent eyes, can run at the speed of 60 km per

hour.

• Foot bear two unequal toes provided with pads, which help the bird in running

fast.

• Lays largest egg produced by any living bird. • Eyes are largest of any land animal.

Kiwi

Apteryx

• It is a New Zealand’s emblem bird. It is the smallest flightless bird. • Good sense of smell and acute hearing, most sensitive beak among birds. • Poor eyesight, male bird builds the nest and incubates sitting on one or more

eggs.

Aptenodytes

Penguin

• Gregarious flightless birds and live in cold sea waters of the South Pole

specially in Antarctica.

• Feeds on fishes, wings are modified into swimming flippers. • Male penguin alone incubates the egg without feeding for two months.

Rhea

South American Ostrich

• Smaller than ostrich but its habits are quite similar to ostrich. • Head and neck are feathered, not naked as in ostrich. • Male is polygamous.

Dromaius

Emu

• Next to ostrich, emu is the largest living bird. • It is confined to Australia, invariably monogamous though seen in small parties

after breeding.

• Male digs the nest and sits over the first brood of eggs, females sit over the second

brood.

Casuarius

Cassowary

• • • • •

World’s third largest flightless bird. Lives in Australia, New-Guinea and adjacent islands. Shy and nocturnal. Foot has 3-clawed toes. Old males may even attack human beings if disturbed. Flying birds

Choriotis nigriceps

Great Indian Bustard

• Inhabitant of the semi-arid areas of Rajasthan, Gujarat and Maharashtra. • State bird of Rajasthan. • Hunting for its flesh has reduced its population. Highly endangered bird.

Eudynamis scolopaceus

Koel, kokila

• The male sounds like kuoo-kuoo-kuoo, female is generally heard during breeding

season and has a short and sharp call kik-kik-kik, otherwise she is mostly silent.

• It does not make any nest but lays eggs in the crow’s nest. Known as the

Indian nightingale because of its pleasant call.

Corvus splendens House crow

Psittacula eupatria

Parrot

• • • •

It is abundantly found throughout the peninsula of India. Both sexes are similar. Crows are intelligent and cunning birds. Omnivorous.

• It is common in India, Bangladesh, Sri Lanka and Burma. • The beak is short but stout, sharp edged, deeply hooked and coral red. • The female is green all over, but the male has a rose pink collar and a black

throat.

• Parrots can copy and speak some words like man. • Popular domestic cage birds. • It carries the germs of the disease called psittacosis, which can be fatal. 70

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Anas

Duck

• Well adapted for swimming, eats mosquito larvae, small fishes, grains and

vegetables.

• Male duck (drake) bears a characteristic copulatory organ.

Columba livia

Pigeon

• Pigeons are gregarious, omnivorous. • The cavity of the gizzard of the pigeon always contains small pieces of stones and

bricks swallowed by the bird. These pieces of stones and bricks helps the gizzard in grinding up the food. • Monogamous. • Young ones are fed upon by both male and female on ‘pigeon milk’. Gallus gallus

Red jungle fowl

• Exhibit sexual dimorphism. • Fowl (common word for cock and hen) provides good food for human beings. • Their eggs have good food value and are hence commonly eaten by men.

Pseudogyps bengalensis

White rumped vulture (Gidh) .

• Flies very high in the sky for hours together. • Acts as a natural scavenger. • Parental care is offered by either sex.

Bubo bubo

Great horned owl (Ghughu)

• Distributed worldwide. • Two prominent feather tufts above head look like ears, hence the name great

horned owl.

• Fully feathered legs are characteristic of horned owl. • It is a nocturnal bird. • It is of great economic value to agriculture as it feeds on harmful rodents.

Ketupa zeylonensi

Brown fish owl (Ulloo)

• Common throughout India. • Similar to the horned owl in all respects, but its legs are unfeathered.

Milvus migrans

Common pariah kite (Cheel)

• • • •

Pavo cristatus

Peacock (Mor)

• Polygamous, usually one male lives in the company of four or five females. • Before copulation male exhibits sexual display, male has the bright blue neck,

It is found throughout India, Pakistan, Bangladesh, Sri Lanka and Burma. True scavenger, feeds largely on flesh. Beak can tear flesh into pieces. Are destructive to chicks, young turkeys and ducklings.

breast and long beautiful tail.

• Indian peacock is the National bird of India.

Economic importance • Chickens account for much of human poultry consumption,

• • •

•

•

though turkeys, ducks, and geese are also relatively common. Many species of birds are also hunted for meat. Bird hunting is primarily a recreational activity except in extremely undeveloped areas. The most important birds hunted in North and South America are waterfowl; other widely hunted birds include pheasants, wild turkeys, quail, doves, partridge, grouse, snipe, and woodcock. Other commercially valuable products from birds include feathers (especially the down feathers of geese and ducks), which are used as insulation in clothing and bedding, and seabird faeces (guano), which is a valuable source of phosphorus and nitrogen. Birds have been domesticated by humans both as pets and for practical purposes.

• Colourful birds, such as parrots and mynas, are bred in

captivity or kept as pets, a practice that has led to the illegal trafficking of some endangered species. • Falcons and cormorants have long been used for hunting and fishing, respectively. • Today, such activities are more common either as hobbies, for entertainment and tourism, or for sports such as pigeon racing. • Birds can act as vectors for spreading diseases such as psittacosis, salmonellosis, campylobacteriosis, avian tuberculosis, avian influenza (bird flu), giardiasis, and cryptosporidiosis over long distances. Some of these can also be transmitted to humans.

Conservation • The most commonly cited human threat to birds is habitat

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71

and predation from non-native invasive species, and climate change. • Governments and conservation groups work to protect birds, either by passing laws that preserve and restore bird habitat or by establishing captive populations for reintroductions.

• Such projects have produced some successes; one study

estimated that conservation efforts saved 16 species of birds that would otherwise have gone extinct between 1994 and 2004, including the California Condor and Norfolk Island Green Parrot.

Some important facts • • • • • • • • • • • •

4. 5. 6.

Study of birds is called ornithology. Modern birds appeared in Cretaceous period. T. H. Huxley called birds to be glorified reptiles. Archaeopteryx lithographica was discovered in 1861 by Andreas Wanger at Bavaria of Germany. Birds are the only amniotes whose bodies are highly specialised for aerial mode of life. Marine birds have salt-glands. Bee Humming Birds (Cuba) Mellisuga helenae is the smallest bird (length 5.5 cm) which can fly in both direction, forward and backward. Dodo Raphus cucullatus is a flightless bird of Mauritius which is now extinct. Famous Indian ornithologist is Dr. Salim Ali (Bird Man of India). Nidology is study of bird’s nests. Poisonous bird, Pitohui dichrous (hooded pitohui) ofPapua, New Guinea, possesses toxins in its skin and feathers. Hornbill is emblem of BNHS (Bombay Natural History Society).

Discuss various aerial or flight adaptations present in birds. What do you mean by migration in case of birds? Discuss various types of migration that are observed in birds. What are the different types of feathers present in birds? Discuss some important functions of feathers.

1. Kidney of adult reptile is (a) metanephric (b) (c) protonephric (d) 2. The ‘Golden age of reptiles’ is (a) palaeozoic era (b) (c) mesozoic era (d)

mesonephric all of these carboniferous era archezoic era.

3. Mammal like reptiles belong to (a) anapsid line of evolution (b) euryapsid line of evolution (c) parapsid line of evolution (d) synapsid line of evolution. 4. Turtles are included in the order (a) Chelonia (b) Rhynchocephalia (c) Squamata (d) Crocodilia. 5. Interclavicle in repitle is (a) H-shaped (b) W-shaped 72

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(c) T-shaped

(d) A-shaped.

6. Heart in crocodiles is (a) completely 4 chambered (b) incompletely 4 chambered (c) 3 chambered (d) 2 chambered. 7. The identifying character of cobra is (a) round tail (b) small scales on head (c) presence of hood (d) third supralabial touches eye and nostril. 8. Which one of the following in birds, indicates their reptilian ancestry? (a) Two special chambers crop and gizzard in their digestive tract (b) Eggs with a calcareous shell (c) Scales on their hind limbs (d) Four-chambered heart

9. The scientist, who described the birds as glorified reptiles, was (a) Romer (b) Mendel (c) Huxley (d) Robert Hooke. 10. Flightless birds are included in (a) odontognathae (b) impennae (c) ratitae (d) carinatae. 11. The character of living birds without exception is (a) omnivorous (b) beak without teeth (c) flying wings (d) monogamous. 12. The special sound producing organ in birds is (a) larynx (b) syrinx (c) oesophagus (d) glottis.

13. Raptorial feet are found in (a) vulture (b) crow (c) mynah (d) lapwing. 14. Some vertebrae in birds fuses to form (a) sacrum (b) synsacrum (c) coccyx (d) none of these 15. Flight muscles of birds are attached to (a) keel of sternum (b) clavicle (c) pelvic girdle (d) humerus.

ANSWER 1. (a) 6. (a) 11. (b)

2. (c) 7. (c) 12. (b)

KEY

3. (d) 8. (c) 13. (a)

4. (a) 9. (c) 14. (b)

5. (c) 10. (c) 15. (a) 

EXAM ALERT! CENTRAL BOARD OF SECONDARY EDUCATION ALL INDIA PRE-MEDICAL/PRE-DENTAL ENTRANCE TEST- 2016

O

nline applications are invited for All India Pre-Medical/Pre-Dental Entrance Test -2016 to be held on 1st May, 2016 (Sunday) for admission to MBBS/ BDS Courses under 15% All India Quota seats as per the directives of Hon’ble Supreme Court of India and also for seats under the control of participating States/Universities/Institutions in the academic session 2016-17. PATTERN OF EXAMINATION The AIPMT Examination shall consist of one paper containing 180 objective type questions (four options with single correct answer) from Physics, Chemistry and Biology (Botany & Zoology). The duration of paper would be 03 hours from 10.00 a.m. to 01.00 p.m. ELIGIBILITY CRITERIA (i) Indian Nationals and Overseas Citizens of India are eligible for appearing in the All India Pre-Medical/Pre-Dental Entrance Test (AIPMT). (ii) The candidate must have completed age of 17 years at the time of admission on or before 31st December, 2016. (iii) The upper age limit for candidates seeking admission under 15% All India Quota Seats is 25 years as on 31st December, 2016 relaxable by a period of 5(five)years for SCs/STs/OBCs. (iv) The upper age limit for candidates seeking admission in MBBS/BDS seats under the control of participating States/Universities/Institutions shall be as per the rules of the State/University/Institution concerned. (v) The candidate must have passed in the subjects of Physics, Chemistry, Biology/Bio-technology and English individually. The candidates from the other

categories must have obtained a minimum of 50% marks taken together in Physics, Chemistry and Biology/Bio-technology at the qualifying examination and candidates belonging to Scheduled Caste/Scheduled Tribes or Other Backward Classes, must have obtained 40% instead of 50%. Further, for persons for locomotory disability of lower limbs, the minimum of 45% marks for General-PH and 40% marks for SC-PH/ST-PH/OBC-PH are required. Those who are appearing in class XII examination in 2016 may also appear for the entrance test provisionally subject to their fulfilling the conditions later. (vi) Candidates from the States of Andhra Pradesh, Telangana and J & K are not eligible for 15% All India Quota seats as these states had opted out of All India Scheme since its inception. However, they are eligible to appear in AIPMT for admission in AFMC, Pune. PARTICIPATING STATE GOVERNMENTS / uNIVERSITIES/ INSTITuTIONS The states of Haryana, Himachal Pradesh, Madhya Pradesh, Manipur, Meghalaya*, Odisha, Rajasthan, UT of Chandigarh, University of Delhi, Armed Forces Medical College, Banaras Hindu University and Hamdard University, New Delhi have decided to voluntarily use the merit list of AIPMT-2016 for admission in the Medical Colleges/Dental Colleges for seats under their control. Candidates who wish to seek admission in these State/University/Institution(s) may confirm eligibility conditions from the respective States/University/ Institutions concerned in advance. *Subject to confirmation from state government.

For more details visit the website www.aipmt.nic.in

SCHEDuLE WITHOuT LATE FEE Schedule for on-line submission of application forms Last date for successful final transaction of fee

For fee through e-challan

For fee through other e-modes

15.12.2015 (Tuesday) to 08.01.2016 (Friday)

15.12.2015(Tuesday) to 12.01.2016 (Tuesday)

12.01.2016 (Tuesday)

12.01.2016 (Tuesday)

WITH LATE FEE Schedule for on-line submission of application forms Last date for successful transaction of fee

For fee through e-challan

For fee through other e-modes

13.01.2016 (Wednesday) to 06.02.2016 (Saturday)

13.01.2016 (Wednesday) to 10.02.2016 (Wednesday)

10.02.2016 (Wednesday)

10.02.2016 (Wednesday)

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WHITEFLY RESISTANT TRANSGENIC PLANT Developed by NBRI

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hiteflies are small hemipterans that typically feed on the underside of plant leaves. It is a common pest which affects 30 plant varieties including cotton, brinjal, papaya, tomato, okra, cucurbits. It sucks all nutrients from leaves and excretes on the leaf’s surface, thus causing fungal infection. Crops infested with whitefly remain stunted. Once the pest spreads, it can destroy the crop quickly. This year, it has affected about two-third of standing cotton crop in Punjab thus, leading to huge economic loss. Large number of farmers committed suicide due to this. Whitefly cannot be controlled by spraying pesticides as canopy formed by grown up plants may not let pesticide to act on each and every leaf and whiteflies lay their eggs on the lower region of the plants. In this regard, NBRI, Lucknow, has developed a new transgenic variety of cotton which is resistant to this pest. ‘Coker’ variety of cotton was used for this purpose. In this variety, a gene derived from a vegetable (which remains undisclosed) was introduced. The gene makes whitefly sterile, thus controlling the reproduction of the pest. The protein formed by the gene was safe and also easily digestible in laboratory trials. The technology is now ready for field trials. NBRI has applied for patent for the technology in eight countries.

GHATIXALUS MAGNUS A Novel Third Species of the Western Ghats’ Endemic Genus Ghatixalus

A

new species of rhacophorid tree frog is discovered by a team of researchers comprising of Robin Abraham (a researcher from the University of Kansas, USA), Anil Zachariah (a batrachologist from Wayanad) and Vivek Philip Cyriac (a researcher of the IISER, Thiruvananthpuram) in the Western Ghats in Kadalar High Ranges of Idukki district, Kerala. The discovery has been published in the latest issue of International Taxonomic Journal, Zootaxa. The Western Ghats biodiversity hotspot is a recognised centre of rhacophorid diversity as demonstrated by several recent studies. The Family Rhacophoridae consists predominantly of arboreal tree frogs. The endemic genus Ghatixalus is represented by two species from two separate high-elevation regions within the Ghats. The new species of rhacophorid tree frog is ascribed to the genus Ghatixalus based on “a unique combination of molecular, morphological and larval characteristics”. It has been named Ghatixalus magnus after its large size, making it the biggest known tree frog from the Western Ghats. With this, there are now three nominal species of the Western Ghats’ endemic genus Ghatixalus. The team has also rediscovered a species of bush frog, Raorchestes flaviventris that had been evading for the past few decades. It was first described from Western Ghats by George Albert Boulenger in 1882. Since then, this had never been sighted. The frog has been rediscovered after 132 years.

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Contd. from page no. 30

st

(iii) 1 menstruation at puberty in female is called capacitation. (iv) If human sperm cut in T.S. and seen under light microscope its axoneme will have 9 + 2 arrangement of fibrils, outer 9 fibrils will be triplets. (v) 80 secondary spermatocytes produces 160 sperms in case of human. (a) (ii), (iii) and (iv) (b) (ii) and (iii) (c) (iii) and (iv) (d) All except (v) 122.Signal for parturition originates from (a) hypothalamus, which stimulates release of oxytocin from its neurons (b) fully developed foetus and regressing corpus luteum (c) hypothalamus and placenta (d) fully developed foetus and placenta. 123.Spermatid is converted into sperm by the process named (a) spermatogenesis (b) spermiogenesis (c) spermiation (d) insemination. 124.Which of the following is a correct sequence? (a) Seminiferous tubule → Rete testis → Vasa deferentia → Epididymis → Vasa efferentia → Ejaculatory duct → Urethra. (b) Germinal epithelium → Spermatogonia → Primary spermatocyte → Secondary spermatocyte → Spermatid → Sperm. (c) Corona radiata → Zona pellucida → Perivitelline space → Cortical granules → Plasma membrane. (d) Oogonium → Primary oocyte (at female child birth at dictyotene) → Secondary oocyte (ovulated at 1st metaphase) → Ovum (after release of second polar body). 125.Which of the following is a true statement? (a) Male sex accessory ducts include seminiferous tubules, rete testis, vasa efferentia, epididymis and vas deferens. (b) Normal temperature for sperm development in human is about 34.5° – 35°C. (c) Leydig’s cells of seminiferous tubules secretes testosterone. (d) Mammary glands of human are one typed sebaceous glands. 126.Which of the following hormone is not secreted by human placenta? (a) hCG (b) hCS (c) Progesterone (d) Luteinising 127.Pick the odd one out from each series given below and select the correct option. (i) Scrotum, rete testis, Fallopian tube, vas deferens (ii) Ovary, uterus, vagina, ejaculatory duct (iii) Acrosome, Graafian follicle, corpus luteum, cervix

(iv) Prostate, testis, seminal vesicles, Cowper’s gland (a)

(b) (c) (d)

(i) (ii) Vas deferens Vagina Rete testis Ovary Scrotum Uterus Fallopian tube Ejaculatory duct

(iii) Cervix Graafian follicle Corpus luteum Acrosome

(iv) Cowper’s gland Prostate Seminal vesicles Testis

128.Repair of endometrium is undertaken by (a) LH (b) FSH (c) estrogen (d) prolactin. 129.The following graph shows the levels of pituitary hormones during a menstrual cycle. What do 1 and 2 represent? Pituitary hormone levels

PRACTICE PAPER

Days

(a) (b) (c) (d)

1 LH Estrogen FSH Progesterone

2 FSH Progesterone LH Estrogen

130.Withdrawal of which of the following hormones is the immediate cause of menstruation? (a) Progesterone (b) Estrogen (c) FSH (d) FSH-RH 131.Which of the following is a wrong match w.r.t. menstrual cycle? (a) Follicular growth – FSH and LH. (b) Thickening of endometrium – Progesterone and estradiol. (c) Trigger for ovulation – LH surge. (d) Menstruation trigger – Increased oestrogen. 132.Modification in sperm after insemination, within female reproductive tract, so as to make it capable of penetration into female’s developing gamete is (a) spermarche (b) cortical reaction (c) capacitation (d) menarche. 133.In a normal pregnant woman, the amount of total gonadotropin activity was assessed. The result expected was (a) high level of circulating FSH and LH in the uterus to stimulate implantation of the embryo. (b) high level of circulating hCG to stimulate endometrial thickening directly. (c) high levels of FSH and LH in uterus to stimulate endometrial thickening. (d) high level of circulating hCG to stimulate estrogen and progesterone synthesis. 134.Milk produced during initial few days of lactation is called colostrum which contains several chemicals essential for

development of child. Some of them are MT BIOLOGY

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75

(a) (b) (c) (d)

high Fe and lipid contents high proteins and high vitamin C contents high protein content and IgA all of the above

135.Human placenta is haemochorial type, which of the following is correct about it? (a) There are 3 barriers between foetal and mother’s blood, as endothelium, connective tissue and epithelium of maternal placental part. (b) There are two barriers between foetal and mother’s blood as endothelium and connective tissue of foetal part of placenta. (c) There are two barriers between foetal and mother’s blood as endothelium and connective tissue of mother’s part of placenta. (d) There are three barriers between foetal and mother’s blood as endothelium, connective tissue and epithelium of foetal placental part. 136.Regressed corpus luteum towards the end of menstrual cycle is called (a) corpus haemorhoegicum (b) corpus albicans (c) atristic follicle (d) corpus callosum 137.Male accessory gland, lubricating penis during cohabitation, by its secretion is (a) prostate gland (b) Cowper’s gland (c) Bartholin's glands (d) both (b) and (c). 138.Which of the following is a true statement w.r.t. human reproduction? (a) Egg is cledoic and alecithal. (b) Cleavages are equal and determinate. (c) Human placenta is chorionic, metadiscoidal and deciduate. (d) Corona radiate, in released secondary oocyte is a tertiary egg membrane. 139.Which of the following is incorrect match? (a) Enamel of tooth – ectodermal (b) Eye lens – mesodermal (c) Lungs – endodermal (d) Spleen – mesodermal 140.Which of the following is a wrong match? (a) Birth canal – Vagina only. (b) Clitoris – Homologous to human penis. (c) Myometrium – Middle layer of tissue in uterine wall. (d) Spermiation – Sperms released from seminiferous tubule by this process. 141.In the following pedigree find phenotype of individual indicated as X, if dominant gene is F and recessive allele is f

(a) FF (c) ff 76

(b) Ff (d) either (a) or (b) MT BIOLOGY

TODAY | JANUARY ‘16

142.Vegetative propagule of Agave is (a) leaf buds (b) offset with two groups of rosset leaves (c) slips or sets (d) bulbils. 143.How many of the following organisms are monoecious?

Chara, Papaya, Leech, Marchantia, Maize, Date palm, Tapeworm, Funaria, Earthworm and Common roundworm. (a) 7

(b) 5

(c) 6

(d) 9

144.Oestrous cycle takes place during reproductive life in (a) apes (b) rat (c) monkey (d) human. 145.Which of the following is true w.r.t. grafting? (a) Very commonly practised in monocot plants. (b) In air layering i.e., one typed grafting uses auxin to induce rooting. (c) Stock is shoot piece which is used in grafting. (d) New plant produced after grafting produces fruits similar to scion source. 146.Zygospore differs from zoospore by A. being diploid B. being actively motile C. being sexual spore D. helps in dispersal of species E. does not undergo meiosis before germination. (a) A, C and D only (b) B, D and E (c) A and C only (d) all except ‘B’ 147.To produce 16 male gametes from MMCs how many mitosis and meiosis are required in angiosperms? (a) 8 and 2 respectively (b) 4 and 2 respectively (c) 1 and 4 respectively (d) 16 and 2 respectively 148.Rafflesia like foul smelling flowers are pollinated by (a) beetles and moths (b) moths and flies (c) flies and beetles (d) moths, beetles and flies. 149.Sunscreen lotions may have added pollen products due to (a) presence of saturated fats and carbohydrates (b) presence of saturated fats and smaller oligosaccharides (c) presence of unsaturated fats (d) none of these. 150.Translator mechanism commonly found in (a) Calotropis (b) Zeuxin, an orchid (c) Salvia (d) Fig. 151.How many of the following statements are true w.r.t. sickle cell anaemia? A. It is an example of point mutation, as well as, missense mutation. B. It is a sex-linked recessive trait. C. 6th amino acid of b-chain glutamate is replaced by valine. D. Example of transition type of mutation. E. In an individual with HbA HbS genotype, some RBCs become sickle shaped under the effect of low O2 availability. (a) 4 (b) 5 (c) 2 (d) 3

152. shown symbol of pedigree indicates (a) illicit couple (b) inbreeding (c) increased hybrid vigour in their progeny (d) all of the above. 153.Which of the following are correct matches? A. Green colour of pod in Pisum sativum – Dominant trait. B. Has no father, still has a grandfather – Drone. C. Female heterogametic w.r.t. sex chromosome – Fowl. D. Gene with multiple phenotypes – Polygene E. Mendel’s work was republished, in year 1901 – Journal Flora (a) C and D (b) C, D and E (c) B, C and D (d) all except ‘D’ 154.Seed produced by selfing of true breeding tall plant, was grown in a barren soil, plant grows as dwarf. It was crossed to another tall plant, then which of the following is true about its progeny (a) all tall with genotype TT (b) all tall with genotype either TT or Tt (c) all tall with genotype Tt (d) either (a) or (b). 155.A, B, C and D lies on same chromosome with given distances between them, as AD = 60 morgan, AB = 38 morgan, DB = 22 morgan and AC = 18 morgan. Find the sequence of four genes on the chromosome. (a) A, C, B and D (b) C, A, B and D (c) D, B, A and C (d) any of these. 156.In Drosophila melanogaster eye colour is controlled by 15 different alleles. How many possible genotypes it may have in the population? (a) 120 (b) 45 (c) 450 (d) 150 157.An Individual has genotype PPQqRrSSTtUUVv. How many different genotype it may have in it gametes? (a) 34

(b) (24)2

(c) 16

(d) 128

158.Thalassemia differs from sickle cell anaemia as (a) former is due to qualitative problem of synthesising an incorrectly functioning globin. (b) later is due to quantitative synthesising too few globin molecule. (c) thalassaemia is controlled by autosomal gene, but, sickle cell anaemia is controlled by X linked recessive gene. (d) none of these. 159.From following listed molecules, how many are nucleosides?

Thymidylate, Guanosine, Uridine, Cytosine, Guanilic acid, Adenosine, Adenylate (a) 4

(b) 3

(c) 2

(d) 6

160.Which of the following statements are true w.r.t. human genome? (i) Human genome has 1.4 million SNPs in it. (ii) Poonam and Sumit are siblings, which differs from each

(iii) (iv) (v) (a) (c)

other and their parents by about 0.1 nucleotide sequence of their genome. Chromosome number 1 has maximum number of gene, whereas, chromosome Y has least number of genes. Largest gene being dystrophin with 3.4 million bp’s. Satellite DNA is inert but shed light on chromosome structure, dynamics and evolution. (ii), (iii) and (iv) only (b) (iii), (iv) and (v) only (i), (ii) and (iii) only (d) all except (iv)

161.Which of the following is true statement? (a) Pribnow box lies in mRNA in upstream stream sequence. (b) In clover leaf model of tRNA, amino acid is attached to 5′ by ester bond, if it is a charged one. (c) Translation is initiated by s factor, formed of γ-chain, of RNA polymerase enzyme. (d) Sn RNA, 5S RNA and tRNA are transcribed with the help of RNA polymerase III in eukaryotes. 162.Which of the following statement is true w.r.t. structure of DNA (Watson and Crick Model)? (a) Base pair rise 34 Å (b) Pitch of DNA 3.4 Å (c) Two strand antiparallel due to formation hydrogen bonds. (d) Two strands are coiled upon one another to form right handed helices. 163.DNA with one strand labelled with radioactive thymidine. Allowed to replicate in normal nutrient medium for three generations. Then proportion of DNA molecules showing radioactivity is (a) 12.5% only (b) 25% (c) 6.25% (d) 50%. 164.‘Myotonic dystrophy’ in human is controlled by (a) X-linked recessive gene (b) X-linked dominant gene (c) autosomal dominant gene (d) autosomal recessive gene. 165.How many of the listed characters are not indicative Down’s syndrome?

Big and wrinkled tongue, Gynaecomastia, Simple palm crease, Under developed feminine characters, Broad flat face, Azoospermia, Congenital heart disease (a) 2

(b) 1

(c) 3

(d) 4

166.Match the following column-I with column-II and find the right match. Column-I Column-II A. Down’s syndrome (i) Trisomy of 13th chromosome B. Turner's syndrome (ii) Trisomy of sex chromosome C. Patau’s syndrome (iii) Autosomal dominant character D. Klinefelter's syndrome(iv) Monosomy of sex chromosome E. Huntington's chorea (v) Non disjunction of autosomes MT BIOLOGY

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77

(c)

Promoter Strand A

3 5

5 3 Strand B

Terminator

(a) If strand A is antisense it will have 5′ towards left side in diagram. (b) If strand B is coding, it will have 5′ towards left side in diagram. (c) If strand B is –ve strand, it will have 3′ towards right side. (d) Both (a) and (c). 168.Which of the following is a wrong match? (a) 3′UAG5′ – Non sense codon (b) UGG – Codes for tryptophan (c) s Factor – initiates transcription (d) None of these

176.Multiple alleles controlling which of the following characters A. Eye colour in Drosophila B. ABO blood groups in human C. Skin colour in human D. Sickle cell anaemia E. Thalassaemia (a) B and C (b) A and D (c) A and B (d) all except D. 177.In the diagram amino acid ‘Ala’ at the tail of arrow ‘X’ contribute (i) group and amino acid val at head of arrow ‘X’ contribute (ii) group for formation of bond between these two amino acids. Gly Leu Tyr

173.Tailoring of hnRNA to produce tRNA is carried out by (a) scrup (b) Intron (c) 18 S rRNA (d) Snurp. 174.Uniequivocal proof that DNA is a genetic material, made use of (a) Streptococcus and T2 (b) 15N as ammonium chloride and density gradient equilibrium technique 78

MT BIOLOGY

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‘X’

Ser Growing polypeptide chain Leu

Asn

tRN

A

Gly Ser Ala

Val

tRNA

tRNA

CG U C A A

170.One codon can undergo how many transitions? (a) 9 (b) 6 (c) 3 (d) 549

172.Which of the following statements is false? (a) 2 turns of Z-DNA has 48 nucleotides. (b) 5′AUG GAC GGG GCG GCC UAG AAC3′ segment of mRNA will not be translated fully. (c) 3-D model of tRNA, where it has inverted L-shaped structure was given by Rich and Klug. (d) To form 1st peptide bond during protein synthesis four phosphate bonds are used.

(d) none of these

175.Match the following column-I with column-II and find the right match. Column-I Column-II A. Non-parental gene (i) Crossing over combination B. Non-sister chromatids (ii) Z and W C. Sex chromosomes (iii) Sex-linked recessive disease D. Haemophilia (iv) Recombination (a) A-(II), B-(IV), C-(I), D-(III) (b) A-(IV), B-(I), C-(II), D-(III) (c) A-(II), B-(IV), C-(III), D-(I) (d) A-(II), B-(I), C-(IV), D-(III)

169.How many of the following statements are incorrect statements? A. 3rd base of anticodon is wobble base. B. Most abundant RNA in the cell is rRNA. C. Coding part of split gene is intron. D. Z-gene of lac-operon produces hydrolytic enzyme. E. 23S rRNA in eukaryotic ribosome is a ribozyme catalysing the formation of peptide bond. (a) 3 (b) 2 (c) 4 (d) 1

171.DNA base sequence is polymeric if (a) it is present in more than 1000 genes (b) a variant sequence exist in at least 1% of population (c) it can’t be cut by exonuclease and endonuclease enzyme (d) the carrier frequency is between 2-8%.

P and 35S isotops

A

167.Diagram shown below is schematic structure of “transcription unit”. Which of the following is true w.r.t. shown diagram?

32

tRN

(a) A-(iii), B-(iv), C-(i), D-(ii), E-(v) (b) A-(v), B-(iv), C-(i), D-(iii), E-(ii) (c) A-(v), B-(iv), C-(i), D-(ii), E-(iii) (d) A-(iii), B-(i), C-(iv), D-(ii), E-(v)

5

(a) (b) (c) (d)

mRNA



Ribosome

(i) – P – H and (ii) – COOH (i) – NH2 and (ii) – COOH (i) – P – OH and (ii) – NH2 (i) – COOH and (ii) – NH2

178.In the given clover leaf model of tRNA recognised the labelled part as Z. (a) T y C loop (b) DHU loop (c) D-loop (d) CCA terminus

Ser

‘z’

U

C

A

179.10% crossing over leads to (a) 10% recombination (b) 20% recombination (c) 5% recombination (d) statement of question is wrong because %age recombination has no relation to %age crossing over. 180.Mechanism of sex determination in honey bee is (a) XX – XO (b) 2n – n (c) arrhenotoky (d) thelotoky.

sOLuTIOns 1.

2. 3.

4.

5.

st

(c) : Refer to 1 paragraph page number 19 NCERT +1; refer to

page number 20; 3rd paragraph which indicates mycoplasma can survive without oxygen, so, facultative aerobic, for methanogen refers to page number 19 article 2.1.1. NCERT +1. (d) : Citrus canker disease is caused by Xanthomonas citri. (a) : For size of bacteria (1-2 mm) refer to diagram 8.2 page number 128 NCERT +1; refer to 2nd paragraph under article 8.4.1 page number 128 for glycocalyx; for fimbriae refer to 3rd paragraph on page number 129. Folds of mesosomes contain component of ETC so helps in aerobic respiration. mRNA (not rRNA) attached to many ribosomes is a polysome. (c) : 8 Bacteria divides repeatedly, three times to produce 64 bacteria, so, time consumed for one binary fission cycle is total time divided by 3 i.e., 120/3 = 40 m. (a) : Whole body of fungus produced from one spore is mycelium, whereas one thread like structure in it is hypha acting as building block of fungal body; exchange of gases in lichens takes place through cyphella, oospore is diploid. Trichonympha in the intestine of termite digests cellulose and provides food to it.

6.

(a) : For dikaryon refer to 2nd paragraph on page number 23 NCERT +1; Sooty mass of spore production is characteristic of smut, which is caused by Ustilago mainly, not by Puccinia; for choice number (iv) refer to last two lines of page number 24 NCERT +1; Morchella is an edible morel member of Class Ascomycetes, not Basidiomycetes.

7.

(d) : Bracket fungi like Polyporus damage our timber resource. For Neurospora refer to last two lines of 1st paragraph page number 24 NCERT +1; for Albugo refer to page number 23, article 2.3.1 NCERT +1; Conidiospores are characteristic spores of both the Classes Ascomycetes and Deuteromycetes.

8.

9. 10.

11.

12.

13.

(b) : Agaricus, puff balls, Ustilago and Puccinia are members of Basidiomycetes i.e., 4 members only whereas Aspergillus, Claviceps and edible morels belong to Ascomycetes; Albugo belongs to Phycomycetes; Alternaria and Trichoderma belong to Deuteromycetes. (d) : Refer to 3rd paragraph page number 23 NCERT +1, these three criteria are used in classification. (c) : Diagram 2.5 (c) shows the labelled parts, your tutor might have explained it (gap in NCERT). Label 1 is hypha producing fruiting body, it is dikaryotic; Label-2 stipe is edible, formed of secondary mycelium; Label-3 Annulus is remains of velum which protects young developing gills; Label 4 gills help in production of basidiospores from its hymenium part. (c) : Cyanobacteria always lack flagella and fimbriae, but, bacteria may contain it; in both the bacteria and cyano-bacteria, DNA lacks histones, so, it is a similarity; anoxygenic photosynthesis found in bacteria, but, cyanobacteria have oxygenic photosynthesis; stored food in bacteria is glycogen but cyanobacteria mainly have cyanophycean starch; bacteria lack heterocyst but cyanobacteria contain heterocysts. (b) : X- is Nitrosomonas and Y- is Nitrobacter; Gram -ve bacteria are resistant to most of the antibiotics; Frankia fixes N2 in nonleguminous root nodules. (a) : As fungi grow in dark, warm and humid conditions.

14. (d) : Bacterial cell wall contains N-acetyl glucosamine (NAG) in carbohydrate part of cell wall and chitin is a polymer of NAG. 15. (c) : Refer to table 3.1 indicating differences among different classes of algae, page number 33 NCERT +1. 16. (c) : In algae, vegetative reproduction mainly takes place by fragmentation not by any asexual or sexual spore. 17. (a) : For (i) refer to last line page number 30 NCERT +1; (ii) refer to page number 32, 1st paragraph +1 NCERT; (iii) Sphagnum is a bryophyte where sporophyte is parasite on gametophyte; Refer to diagram 3.2 page number 34 NCERT +1. SCP mean single cell protein i.e., protein of microbial origin, like Chlorella and Spirullina are good source of SCP. 18. (c) : Prothallus is a gametophyte; strobilus is another name of cone; inducium is a protective covering of sorus. 19. (a) : 2 × 10 × 4 × 5 × 6 × 4 = 9600 is the total number of spores produced on 2 sporophylls. 20. (a) : Floridean starch has structure similar to amylopectin and glycogen (refer to page number 33 NCERT +1). Sphagnum bears both male and female sex organs on same plant, so monoecious. It bears male and female sex organs on different branches so autoecious, but, Marchantia bears male and female sex organs on different plants so dioecious; sphenopsids contain brown, nonphotosynthetic scale leaves so photosynthesis is carried out by green stem. 21. (d) : Protonema is found only in mosses not in liverworts. 22. (a) : Only fern zygote is diploid; all other cells listed here are haploid. 23. (c) : Heterospory originated in lycopods like Selaginella. 24. (d) : Endosperm in gymnosperms is haploid structure. Endosperm contains 16 chromosomes. It is a ‘n’ number of chromosome; leaf and MMC being 2n contain 32 chromosomes; pollens being ‘n’ contain 16 chromosomes. 25. (a) : Because, only, in bryophytes sporophyte is parasite on gametophyte. 26. (a) : Salvinia is a heterosporus fern. Selaginella is also heterosporus, but, it is a lycopod not a fern. 27. (c) : Refer to diagram 3.4 (c) on page number 39 NCERT +1. 28. (c) : Walking fern is Adiantum caudatum because of apical reproductive buds on leaves which after coming in contact with the soil help in spreading on ground; bog moss is Sphagnum, Cycas living fossil because of ciliated sperms; maiden hair tree is Ginkgo. 29. (d) : Refer to article 3.4 on page number 38 NCERT +1. 30. (c) : Indicated feature is of bryophyte and Marchantia is a bryophyte. 31. (a) : Peat is an inferior quality coal, carbonised dead body of Sphagnum used as a fuel, bryophytes are highly important ecologically as they help in soil formation and ecological succession; Male cone of Pinus equivalent to angiospermic flower for being axillary in position; Endosperm of Cycas is a prefertilisation product derived from female gametophyte. 32. (b) : Refer to figure 3.1 page number 31 and figure 3.3 page number 37 NCERT +1. MT BIOLOGY

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33. (c) : Bryophytes differ from pteridophytes by lacking vascular tissue not by containing vascular tissue. 34. (d) : Refer to last four lines of page number 38 NCERT +1. 35. (a) : During forest fire rhizomes survive below the surface of soil, after forest fire they regenerate new plants; chilgoza nut is a seed not a fruit, ovuliferous scales are equivalent to carpels. 36. (c) : Refer to last paragraph on page number 35 NCERT +1. 37. (a) : (i), (ii) and (iii) are features of gymnosperms, according to NCERT life cycle of gymnosperm is diplontic; all gymnosperms are heterosporus. 38. (c) : Life of sporophyte starts with zygote, so first cell in life of sporophyte is zygote, whereas, gametes fuse to form zygote, so gametes are last cells in the life of gametophyte. 39. (c) : Marchantia being a liverwort has unicellular rhizoids; Sphagnum contains water storing retort cells in the ‘stem’. 40. (c) : Thallophytes contain non jacketed unicellular sex organs, commonly. 41. (d) : Gymnosperms contain archegonia but lack antheridia. 42. (d) : Refer to 2nd paragraph on page 38 NCERT +1. 43. (d) : Archegonium of gymnosperm contains highly reduced neck, without neck canal cell (N.C.C.). 44. (d) : Funaria and Pinus both lack fruit so similarity, but, Funaria produces antheridium and archegonia, Pinus contains archegonia but lacks antheridium, but, Pinus produces seeds but Funaria lacks seeds. 45. (d) : Prothallus of fern is a gametophyte which produces gametes. Strobilus, sporangia and sorus are found on sporophyte, not on prothallus. 46. (b) : Both are terrestrial and have main body as gametophyte, bryophytes contain sterile jacket around sex organs; gametes are not multiflagellated. 47. (b) : In Funaria, sporophyte is a parasite, all the three contain archegonia; vascular tissue absent in Funaria; in Ginkgo gametophyte highly reduced in comparison to sporophyte and parasite on sporophyte. 48. (d) : They live on damp, cool and shady place and need water for fertilisation so have limited geographical distribution. 49. (c) : Presence of seeds and flagellated sperms together is unusual in plant kingdom, as found in some lower gymnosperms like cycads. 50. (c) : Double fertilisation is found in all angiosperms. 51. (d) : Unique features to mammals are mammary glands and hair (refer to last two lines on page number 61 NCERT +1); protochordates do not include hemichordates. All vertebrates are chordates. 52. (a) : (ii) and (v) are wrong. Echinoderms contain water vascular system, not canal system; reptiles are amniotes. 53. (d) : Body of hemichordates like Balanoglossus is divisible into proboscis, collar and trunk. 54. (c) : Collar cells are characteristic to sponges; uropygeal gland found in birds; Struthio flightless bird, so, lacks well developed keel. Swim bladder not found in Chondrichthyes like Scoliodon. 55. (d) : Metameric segmentation found in all the listed three phyla. 56. (d) : Amphioxus, a chordate contain flame cells; crop and 80

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57. 58.

59. 60.

61. 62. 63. 64.

65. 66. 67. 68.

69. 70. 71.

72. 73. 74.

75. 76. 77. 78. 79.

gizzard found both in birds and cockroach, collar cell is found in canal system, colloblast attaching cells on tentacles of ctenophores, tornaria larva found in phylum Hemichordata, like Balanoglossus. (b) : Echinodermata is the only phylum that contains bilaterally symmetrical larva and radially symmetrical adult. (a) : Taenia and dog tapeworms lack alimentary canal; Fasciola contains incomplete alimentary canal; so, lacks anus, Amphioxus being chordate contains complete alimentary canal. (d) : Filaria is caused by Wuchereria bancrofti, a round worm. Culex mosquito is vector not a cause of disease. (a) : Excretory organ of hemichordata is proboscis gland refer to article 4.2.10 page number 54 NCERT +1. Amphioxus contain flame cell and prawn has green gland as excretory organ. (b) : All the listed characters pertains to Aschelminthes and Ascaris is its member. (b) : Sea fan is Gorgonia, a Cnidarian. (d) : Refer to article 4.2.2, 3rd and 4th line on page number 50 NCERT +1. (a) : Vector for Wuchereria is a female culex, Peripatus is connecting link of annelida and arthropoda, chloragozen cells of earthworm are equivalent to human liver because both can store glycogen. (b) : Locust is a gregarious animal, instead of colonial. (d) : Female Aedes mosquito acts as a vector of Dengue. (b) : Tornaria larva – Balanoglossus; Brachiolaria – Starfish; Axolotl – Salamander; Trochophore – Nereis. (c) : Osphradium of Pila is a chemoreceptor which is a leaf like structure checks chemical nature of water which enter the pallial complex of Pila. (b) : Neophron written in italics is a biological name of vulture. It is not a functional unit of kidney, which is a "nephron". (c) : Refer to diagram 4.21 and 4.22 on page number 57 and 58 of NCERT +1. (b) : Doliolium is a hemichordate one typed protochordate; Ichthyophis is a limbless amphibian; Ornithorhyncus (duck billed platypus) is an egg laying mammal; Delphinus (Dolphin) is an aquatic mammal; Myxine (Hag fish) is a jawless fish. (c) : Study comparison of cyclostomes, chondrichthyes and osteichthyes from NCERT pages 56 and 57 NCERT +1. (a) : Some crustaceans, aquatic amphibians and amphibians are not uricotelic. (b) : All sponges have high regeneration power due to presence of archaeocytes in their body wall. Some sponges may contain silicious spicules; mostly found in warm water, Spongilla is a fresh water sponge, mostly they are asymmetrical. (d) : Both (C) and (D) have true coelom as schizocoelom. (a) : Scorpion, spider and cockroach all have ventral solid nerve cord, for being invertebrates. (a) : Diagram A-true coelom – Annelids; B-pseudocoelom – Aschelminthes; C-Acoelomate – Platyhelminthes. (d) : Nereis, housefly and roundworms are unisexual organisms. (b) : Listed characters pertain to phylum Arthropoda.

80. (c) : Post anal tail is a feature of chordates, only, snake in the choices is a chordate. 81. (a) : Deuteromycetes are called imperfect fungi because they lack perfect stage i.e., sexual stage or this stage has not yet been reported. 82. (c) : Cell wall of diatoms is indestructible and embedded with silica. 83. (c) : In higher fungi (Ascomycetes and Basidiomycetes) distinct dikaryophase is present during sexual life because there is a time gap between plasmogamy and karyogamy. 84. (a) : Due to complimentary chromatic adaptations red algae show change in colour from top to bottom of sea water. 85. (b) : Sporophyte of bryophytes is parasite or dependent on gametophyte; sporophyte lack root like structures to absorb nutrition from damp soil, both statements are true without direct relation. 86. (b) : Assertion and reason are two independent true statements. 87. (b) : Both statements are true without any direct relation. 88. (b) : Both are independently true statements. 89. (d) : Polyp produces medusae asexually and medusae for polyp sexually so, A is a wrong statement. Polyp and medusa are not, common, to different group of cnidarians. 90. (a) : As in platyhelminthes blastopore develops into mouth, all of them are protostomes. 91. (d) : Fruits produced from ovaries without the act of fertilisation are parthenocarpic not parthenogenetic, ovary wall mature into pericarp not testa. In angiosperms endosperm development preceeds not proceeds the development of embryo. 92. (c) : One meiosis produces 4 pollen and each pollen produces 2 male gametes, so, one meiosis produces 8 male gametes, so

96 = 12 meiosis are required to produce 96 male gametes. 8

93. (c) 94. (a) : Tassels you see are nothing but stigma and style which wave in wind to trap pollens; (page number 29 NCERT +2 last but one sentence of 1st paragraph) cleistogamy is one typed self pollination i.e., inbreeding leads to inbreeding depression, so, loss of hybrid vigour; read Geitonogamy at page number 28 NCERT +2. In Eichhornia flowers are above the water level and purple in colour, so, pollinated by bees, dioecy is unisexuality of plant, so, no possibility of self pollination. 95. (a) : Page number 22, NCERT +2 Ist paragraph. 96. (c) : Double fertilisation was discovered by Nawaschin in Lilium, and Fritillaria but, in Monotropa plant fertilisation was discovered by Strasburger. Polygonum type of embryosac is monosporic typed. 97. (d) : C-of shown diagram is a zygote, not an embryo, as it is unicellular. A-produces 3n endosperm (based upon figure 2.13(a) page number 34 NCERT +2). 98. (a) : Carpel is modified megasporophyll and mega-sporangium modifies to form ovule. 99. (b) 100. (d) : Orchid are monocot producing non endospermic seeds, groundnut, pea and mustard are non endospermic dicots. Castor is endospermic dicot, barley, maize and wheat are endospermic monocots.

101.(c) : Read line number four from end of page number 29 NCERT +2. 102.(d) : Bending of pollen tube towards synergid is chemotropic movement, not a chemotactic one. 103.(a) : Aleurone grain layer is a part of endosperm. 104. (a) : In angiosperms pollens are commonly released at 2 celled stage (page number 23, 2nd paragraph NCERT +2). 105. (b) : Page number 35, figure 2.14(a) (check labelling carefully) NCERT +2. 106.(d) 107. (c) : Maize grain is a single seeded fruit cryopsis, so, using formula n × 1.25 (where n is seeds to be produced), the answer should be 125. 108. (c) 109. (d) : Palynology is study of all aspects of pollen grain, canthrophily is pollination by beetle and papaya is a dioecious plant. 110. (d) : Page number 38, read last sentence of NCERT +2. 111. (a) : All sentences are taken from NCERT +2 Chapter 4. 112. (c) : LNG-20 is a hormone releasing IUD so makes uterus unsuitable for implantation (read last paragraph of page number 60 NCERT +2). 113. (a) : All sentences are taken from chapter number 4, NCERT +2. 114. (b) : Please refer to page number 64 read 3rd paragraph NCERT +2. 115.(b) : Refer to page number 64 read 3rd paragraph NCERT +2. 116.(b) : Page number 61, based upon figure 4.4a NCERT +2. 117.(a) : Read article 4.2 from page number 59-60 of NCERT +2 and match the columns. 118. (a) 119. (c) : Totally based upon article 3.4 page number 49, 50 & 51 NCERT +2. 120.(d) : Read last five lines from summary of chapter Human Reproduction at page number 55 NCERT +2. 121.(c) : All sentences are based upon NCERT taken from articles menstrual cycle and gametogenesis. 122.(d) : Read 5th and 6th line under article 3.7 page number 54 NCERT +2. 123. (b) : Read 2nd last sentence of 1st paragraph under the article 3.3 gametogenesis page number 47 NCERT +2. 124. (b) 125. (b) : Seminiferous tubule produces sperms so, not an accessory duct in male reproductive system, Leydig’s cells lies outside the seminiferous tubule, human mammary glands are modified sweat glands, human sperms, develop at temperature 2-2.5°C less than human body temperature (37°C). 126. (d) : LH is produced by anterior pituitary, not by placenta. 127.(d) : All sentences from male and female reproductive systems given in Chapter 3rd of NCERT +2. 128.(c) 129.(c) : Look at Fig. 3.9 page number 50 NCERT +2. 130. (a) : In absence of fertilisation, corpus luteum degenerates leading to decrease level of progesterone which causes disintegration of endometrium. MT BIOLOGY

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131.(d) : Menstruation trigger is decrease level of progesterone due to degeneration of corpus luteum. 132. (c) 133.(d) 134. (c) : Colostrum does not contain Fe and vitamin C, but, colostrum is rich in IgA and protein. 135. (d) 136. (b) 137. (b) 138. (c): Human egg is alecithal, noncledoic. Cleavage in human are taken as equal and indeterminate; corona radiata is a secondary membrane. Human placenta produced from chorion, so chorionic; in the early embryonic stage vili are uniformly distributed over blastocyst and later on remain restricted to discoidal area so metadiscoidal; all extra embryonic membrane are shed from female body, so, deciduate. 139. (b) : Eye lens is ectodermal in origin. 140. (a) : Birth canal is formed of both cervical canal and vagina. (Read 2nd paragraph on page number 46 NCERT +2). 141. (d) : Character is controlled by autosomal recessive gene. 142. (d) : Read label of figure 1.4 on page number 7 of NCERT +2. 143. (c) : Chara, Leech, Maize, Tapeworm, Funaria and earthworm are monoecious mean bisexual. 144.(b) 145. (d) 146. (c) 147. (d) : Two meiosis because meiosis leads to formation of 8 microspores (pollen). Microspores (pollen) 16 mitosis because one pollen produces 2 male gametes by 2 mitosis during development of male gametophyte. 148. (c) : Plants with foul odours are pollinated by flies and beetle, page number 30 NCERT +2. 149. (c) : Unsaturated fats protects skin from UV rays. 150. (a) 151. (d) : Based upon article Sickle Cell anaemia and figure 5.15 given on page number 89 NCERT +2. 152. (b) : Inbreeding because marriage between closely related individuals is one type of inbreeding. 153. (d) 154. (d) 155. (d) :

As relation of gene C with respect to B and D is not given it can be on either side of A. If C is on left side of A, sequence may be CABD or if on right side of A then, the sequence may be ACBD or DBAC. So, the answer is any of these. 156. (a) : To find number of genotypes in a population for given number of multiple allele for a character, formula used is n (n + 1) where n is number of allele controlling a character so

2

15 = (15 + 1) = 120 . here, the number of genotypes = 2

157. (c) : Number of gametic genotypes produced by a hybrid is given by formula 2n, where n is number of hybrid pair of factors in the individual, so 24 = 16. 158. (d) : Refer to last sentence of paragraph under heading thalassemia on page number 289 NCERT +2. 82

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159. (b): Guanosine, uridine and adenosine are nucleosides here cytosine is a nitrogenous base. 160. (d) : Largest gene dystrophin contain 2.4 bp’s. All sentences taken from article salient features of human genome project page number 120 NCERT +2. 161. (d): Pribnow box lies in coding strand of DNA; amino acid binds at 3′ of tRNA by ester bond; Translation initiated by AUG codon where as s factor initiates transcription. 162. (c): Two strands of DNA are antiparallel as phosphodiester linkage is reversed to make H-bonding between A = T & C ≡ G. Reverse order of phosphodiester is the consequence of H-bonding. 163. (a) : Based upon article 6.4.1 page number 104-105 NCERT+2. 164. (c) : Refer to page number 88, figure 5.14 read the label of the figure, NCERT +2. 165. (c) : Gynaecomastia, under developed feminine characters and azoospermia are not the symptoms of down’s syndrome. 166.(c) 167. (b) : Based upon understanding of figure 6.9 page number 108 NCERT +2. 168. (a) : As codons are read from 5′→ 3′ so given codon 3′UAG5′ is GAU not a non sense codon. 169. (a) : 3rd base of codon is wobble base, Z-gene of lac operon produces b-galactosidase which digests lactose to glucose and galactose, so, it is a hydrolytic enzyme, 23S rRNA is a ribozyme, found in prokaryotic ribosome. 170. (c) : As transition is replacement of purine by purine or pyrimidine by pyrimidine so one codon contain three nitrogenous bases it can undergo only three transitions. 171. (b) 172. (d): To form 1st peptide bond 7 phosphate bonds are required (4 from ATP and 3 from GTP). 173. (d) : Tailoring means processing which is carried out by snurp (i.e., splicing only). 174.(c) : Unequivocal proof used 32P and 35S because it was Hershey and Chase Experiment. 175.(b) : Based upon basics of genetics, all given in chapter 5 NCERT +2. 176.(c) : Based upon examples given in chapter 5 NCERT +2. 177. (d) : Ala lies on P-site it will contribute –COOH group and Val lies on A-site will contribute –NH2 group. 178. (a): T y C loop because minor loop or loop III always lies between anticodon and T y C loop. 179.(c) : If 100 meiosis are being studied. They lead to formation of 400 gametes and 10% crossing over lead to formation of 20 recombinant gametes, so, percentage recombination will be

20 × 100 = 5% . 400

180.(b) : Based upon article sex determination in honey bee on page number 288 NCERT +2.



ANSWERS 1. 2. 3.

Mycoplasma Mesosome Pecten

WHO AM I ... Pg. 51 Pg. 56 Pg. 69

Readers can send their responses at [email protected] or post us with complete address by 25th of every month to win exciting prizes. Winners' name will be published in next issue.

ACROSS 7. A protein which forms principal component of bacterial flagella. (9) 12. The highly resistant glycoprotein particles formed due to mutation in gene PRNP. (6) 15. A protein which forms the bacterial appendages which are not used in locomotion. (5) 18. A collection of secretions from the male accessory glands and sperms from testes. (5) 20. An iron containing molecule that binds to protein to form haemoproteins. (4) 22. A condition in which the dissolved oxygen is below the necessary level to sustain animal life. (7) 23. An attachment point in seed through which it attached to the funicle. (5) 24. A somatic hybrid formed as a result of somatic hybridisation. (6) 25. The simplest and the smallest free-living prokaryotes. (9) 27. A poisonous substance produced by Paramecium. (9) 28. The zygote of cellular slime moulds is called ______. (9) 29. A fertile male in a colony of honeybee. (5) 30. A type of asexual reproduction in protozoa. (10) 1. 2. 3. 4. 5. 6. 8. 9.

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10 12 13 15

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18 20

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22 23

24 26

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DOWN Unicellular green algae which act as indicators of clean water. (7) The outermost mucilage layer of the bacterial cell which consists of non-cellulosic polysaccharides. (10) The smallest self replicating particles. (7) An ingrowth of plasma membrane in bacteria which contains respiratory enzymes. (8) A disease in silkworm caused by Nosema bombycis. (7) A vesicle present in Aquaspirillum magnetotacticum having magnetite. (11) A slender pseudopodia with axial support found in amoeboid protozoans. (8) A mass of nervous tissue containing many cell bodies and synapses. (8)

10. A flat, broad and leaf-like mycophycomycetes which is attached to the substratum at one or few places. (7) 11. A disease caused by Trichomonas vaginalis in human females (11) 13. A drug which is derived from opium and used in medicine for inducing sleep. (6) 14. A soluble carbohydrate found in the root tubers of Dahlia. (6) 16. A dual entities having association between fungus and an alga. (6) 17. A glue obtained from red algae; used as adhesive in textiles. (6) 19. A unit prefix in the metric system denoting a factor of one million. (4) 21. A branch of science which deals with the study of various causes of the disease. (8) 26. A highly condensed and specialised underground stem. (4)  MT BIOLOGY

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Y U ASK

WE ANSWER Do you have a question that you just can’t get answered? Use the vast expertise of our MTg team to get to the bottom of the question. From the serious to the silly, the controversial to the trivial, the team will tackle the questions, easy and tough. Few questions and their solutions are printed in this column. For more queries and their answers, please visit www.mtg.in Readers can send their queries at [email protected] or post to us.

Q.1. I am appearing for Class 12th Boards this year. Can you suggest me how should I plan my studies to get good marks? – Nishtha Garg, New Delhi Ans. It is already January, so the syllabus has almost completed in the schools. Thus, your focus should be more on revision and practice. You should keep the following in mind while preparing: (i) Vision and Revision : Though there is no one method of revising that works for everyone, but it is important to cover the whole syllabus on time, so that you have enough time for last revision before an exam. Leaving everything until the last minute reduces chances of success, and leads to stress. (a) Plan your revision timetable and do strictly follow it. (b) Keep track of your progress, topics that you have covered. (c) Make short notes and highlight the text for faster revision. (d) Do as many practice questions as you can. It will help to make concept clear. You can use - “MTG-Excel in Biology” which is very helpful for final revision and would help you to achieve peak performance in board examination. Theory covers all topics and is presented in a manner that you can master on each topic. Practice papers and previous year’s board papers would help you to get deep insight about examination. (ii) Learn the key words : Write the solution according to question only. Use key words in your answers like name, definition, description, explanation. (iii) In the examination : Keep yourself calm and relaxed when you receive question paper and carefully fill your details in response sheet. (a) Do not panic if you are not able to answer any question and do not waste too much time on particular question. (b) Manage your time from beginning, so that you can attempt all questions. (c) Use ‘left over’ time for revision and highlighting important points. 84

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All the Best for your Exam. Show your best, MTG is with you for all kind of assistance. Success is waiting for you. Q. 2.Why the inner portion of some guavas is of red colour?

–Akanksha Deshmukh

Ans. The guava fruit grows on a small tree with a wide, short canopy and a sturdy single to multi-stemmed trunk. The guava tree is an interesting plant with mottled greenish bark and simple, elliptic to ovate leaves. Guava trees produce white flowers that yield to small round, oval or pear shaped fruits. These are more accurately berries and have soft flesh, which may be white, pink, yellow or even red and varies in taste from acidic, sour to sweet, and nutrient content varies depending upon variety. There are many different varieties such as Blitch (pink inside), Mexican Cream (creamy-white), Ruby (red inside) and Supreme (white inside.) Pink guava contains naturally occurring organic pigment lycopene which is a carotenoid, that imparts pink colour to its pulp. The concentration of carotenoid varies from species to species depending upon which guavas range from light pink to deep pink. The carotenoid content of white guava is insufficient to impart colour to its pericarp (pulp). Q. 3.If Apple is cut in pieces, after sometime its colour becomes brownish. What is the reason behind it?

–Sibat Sidiq, Kashmir

Ans. The outer skin of an apple acts to protect the inner pulp against injury. But if this layer is damaged, the cells in the pulp release enzymes which react with oxygen to oxidise the damaged cells and form a protective layer against infection. Thus, the brown colouration in an apple occurs in response to damage caused to the apple. Apples contain an enzyme called polyphenol oxidase that reacts with oxygen and iron-containing phenols that are found in the apple. The oxidation reaction basically forms a sort of rust on the surface of the fruit. Browning of the fruit is seen when it is cut or bruised because these actions damage the cells in the fruit, allowing oxygen in the air to react with the enzyme and other chemicals, as oxygen present in air is an extremely reactive gas. When oxygen enters in the cell, polyphenol oxidase (PPO) enzymes in the chloroplasts rapidly oxidise phenolic compounds, present in the apple tissues to o-quinones, colourless precursors to brown-coloured secondary products. O-quinones then produce the well documented brown colour by reacting to form compounds with amino acids or proteins, or they self-assemble to make polymers.Thus, the brown colour of apple is due to rusting. If we cut a browned apple into two again, we will notice that the insides are still white. That’s because the cells inside were intact, and did not let oxygen enter right inside. 

BIOLOGY TODAY 2015 HIGH YIELD FACTS

MONTHS

BOTANY JAN

Biotic Interactions

FEB

Chromosomal Mutations

MARCH APRIL MAY

.............. Photosynthesis-I Photosynthesis-II

PMT ESSENTIAL

AT A GLANCE PMT FOUNDATION

CONCEPT MAP

ZOOLOGY ..............

Excretion and Osmoregulation

Human Physiology

Nitrogen Nutrition in Plants

Immunology

Transport in Plants - I

Reproduction

Human Male Reproductive System

Sensory Receptors

Transport in Plants - II

Genetics and Evolution

Human Female Reproductive System

Animal Kingdom - I

Ecological Succession

Biology in Human Welfare

Gametogenesis

Breathing and Exchange of Gases

Biotechnology

Five Kingdom Classification

..............

JUNE

..............

Animal Kingdom - II

Origin of Life

Ecology

Metabolism

JULY

Sexual Reproduction in Flowering Plants-I

Animal Kingdom - III

Microbes in Human Welfare

Diversity in the Living World

Cellular Respiration

AUG

Sexual Reproduction in Flowering Plants-II

Animal Kingdom - IV

Animal Husbandry

Structural Organisation in Plants and Animals

Synapse

SEPT

Plant Tissue Culture

Animal Kingdom - V

Biological Classification

Cell: Structure and Functions

Morphology of Roots

OCT

Biodiversity and Conservation

Animal Kingdom - VI

Plant Breeding

Plant Physiology

Morphology of Stem

NOV

Environmental Issues - I

Animal Kingdom - VII

Human Heart

Human Physiology - Part-I

Morphology of Leaf

Animal Kingdom - VIII

Pre-Mendelian and Mendelian Genetics

Human Physiology - Part-II

DEC

Environmental Issues-II

NCERT XTRACT

Inflorescence

SOLVED PAPER (2015)

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JAN

Plant Growth and Development

..............

CBSE Board Unit-V

You Ask We Answer, Biology Olympiad Problems, Concept Booster, Crossword

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Biotechnology-Principles and Processes

..............

CBSE Board 2015

Concept Booster, Crossword Target PMTs, Biology Olympiad Problems, You Ask We Answer, Concept Booster, Crossword

MARCH

..............

..............

CBSE Board 2015

APRIL

..............

..............

Target AIPMT

You Ask We Answer, Target PMTs, Crossword, AIIMS Special

MAY

..............

CBSE Board

Target AIIMS

Target PMTs, AIIMS Special, You Ask We Answer, Bio Bulletin, Crossword

JUNE

..............

AIPMT, WBJEE, Kerala PMT

..............

Target PMTs, Crossword

JULY

..............

MH-CET, COMEDK, KCET

..............

*Mind Bogglers, *Unscramble Me, Crossword

J & K CET

..............

AIIMS’ 15 Toppers Talk, Mind Bogglers, You Ask We Answer, *Spellathon, Unscramble Me, Concept Booster, Crossword

AIPMT (Re-Exam)

CBSE Board Unit-I

Mind Bogglers, AIIMS Special, You Ask We Answer, Spellathon, Unscramble Me, Crossword

Bihar CECE

CBSE Board Unit-II

AIIMS Special, Mind Bogglers, You Ask We Answer, Spellathon, Unscramble Me, Crossword

AUG

Biotechnology and its Application

SEPT

Mineral Nutrition

OCT

..............

NOV

Transport in Plants

..............

CBSE Board Unit-III

Topper’s Talk, AIIMS Special, *Glance Around, Nobel Prize 2015, Spellathon, Unscramble Me, Crossword

DEC

Evolution

..............

CBSE Board Unit-IV

You Ask We Answer, Glance Around, AIIMS Special, *Bio-gram, *Bio-Reporter, Crossword, Unscramble Me, Spellathon

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