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VIKAS PRE – UNIVERSITY COLLEGE, MANGALURU ANNUAL EXAMINATION - ANSWER KEY -2018 II PUC - BIOLOGY

PART A 1.

Process of attachement of blastocyst in to endometrium.

2.

5’ – GAATTC – 3’

3.

Capacity to generate a whole plant from any cell/explant.

4.

Break down of cellulose , is an important role of Methanobacterium in the nutrition of cattle.

5.

Signal for parturition originates from fully developed foetus and the placenta which induce uterine contraction is called Foetal Ejection Reflex.

6.

Single step large mutation causes speciation.

7.

Ig E

8.

Organism can tolerate wide range of temperature.

9.

Increase in concentration of the toxicant in successive trophic level.

10.

Haemozoin.

PART B 11.

Homogametes are gametes which are morphologically similar. Heterogametes are gametes which are morophologically distinct.

12.

Natural selection - Industrial mechanism DDT resistance in mosquitoes

13.

14.

Homozygous Plant

Heterozygous plant

Plants with similar Alleles for the

Plants with dissimilar Alleles for

characters

the characters

Innate immunity is non specific type of defence that is present at the time of birth. Physical barrier, physiological barrier, Cellular barrier, cytokine barrier (any two)

15.

1. Selection of disease free breeds 2. Proper and safe farm condition 3. Proper feed , water hygiene and health care

16.

Micro injection, Biolistics or gene gun.

17.

Endemism is a phenomenon in which species confined to one particular region and not found anywhere else. Western Ghat and Eastern Himalaya

18.

Nile prech, Parthenium

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PART C 19.

a) Offset b) Bulbill c) rhizome

20.

Refer NCRT Text page No:22

21.

In honey bee females are diploid having 32 chromosomes whereas males are haploid having 16 chromosomes. This is called haplo-diploid system

Parents

Female 32

Male 16 Metosis

Meiosis 16 Gametes

F1 22.

16 16 Male 16

Female 32

Allelic frequency in a population are stable and constant from generation to generation. 1) Gene flow 2) Genetic drift (Sewall Wright effect) 3) Recombination 4) Natural selection 5) Mutation

23.

Healthy forest ecosystem, purify air and water, mitigate droughts and floods, cycle nutrients, generate fertile soil, provide wild life habitat, maintain biodiversity, pollinate crops, provide storage sites of carbon and also provide aesthetic, cultural and spiritual value.

24.

Page No: 155 NCERT Text Book.

25.

The gradual and fairly predictable change in species composition of a given area is called ecological succession. Hydrach succession takes place in water and succession series of progress from hydric to mesic condition. xerach succession takes place in dry areas and series of progress from xeric to mesic conditions.

26.

Page No. 119 of NCERT Text Book.

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PART D Section – I 27.

Page No. 26. Diagram of embryosac. Embryosac consist of 7 cells and 8 nuclei – 3 cells are grouped together at micropylar region constitute egg apparatus, which consist of 2 synargids and egg cell. Synergids have special cellular thickening at the mycropylar tip called filiform apparatus., which helps in guiding the pollentubes into the synergid. 3 cells at chalazal region called antipodals. Large central cell has 2 polar nuclei.

28.

Page No. 45 of NCERT Text Book.

29.

Whenever a pair of contrasting characters are brought together in a hybrid they segregate during gamete formation. Stem height- Tall and Dwarf Tall TT

X

Dwarf tt

T

P1 phenotype P1 genotype

t

Tt

Gamets

F1 hybrid

F1 Selfed Tt  Tt T T

t

T

TT tall

Tt tall

t

Tt tall

tt Dwarf

t

T

t

- F2 Generation

Genotypic ratio TT : Tt : tt 1 : 2 :1 Phenotypic ratio : Tall : Dwarf 3 : 1 30.

a) Ideal contraceptive should be i) User friendly ii) Easily available iii) Effective and reversible with no or least side effect iv) should not interfere with sexual drive, desire or sexual act of the user. b) i) Periodic abstinence (ii) Withdrawal or coitus interrupts (iii) Lactational amenorrhea

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31.

a) Inbreeding depression : Continuous breeding reduces fertility and productivity. This is called inbreeding depression. b) Interspecific

hybridization :

Cross between the male and female animals of two

different related species. c) Biofortification: It is the method of breeding crops with higher levels of vitamins and minerals, proteins and healthier fats to improve public health. d) Micropropagation: The method of producing thousands of plants through tissue culture in called micropropagation . e) Somaclones: A group of genetically identical plants produced by tissue culture is called somaclones. 32.

The lac operon is the unit of gene expression in bacteria, which codes for genes responsible for lactose metabolism. 1. Switched off mechanism: In the absence of inducer (lactose), the repressor protein produced by regulator gene (inhibitor gene(I)]binds with the operator gene (O). Now operator gene cannot allow RNA polymerase to bind with the promoter region (P) due to lack of space. In the absence of RNA polymerase, the structural genes do not produce polycistronic m-RNA and enzymes and the lac operon is switched off. 2. Switched on mechanism: In the presence of inducer, the repressor protein produced by regulator gene [inhibitor gene (1)], binds with the inducer and undergoes conformational changes and becomes inactive: inactive repressor cannot bind to operator gene(O). In the absence of repressor, operator gene allows RNA polymerase to bind with the promoter region(P). In the presence of RNA polymerase the structural genes produce polycistronic m-RNA and enzymes and the lac operon is switched on. Refer Fig. No: 6.14 of NCERT Text Book.

Section – II 33.

Oswald Avery, Colin MacLeod and Maclyn MeCArty (1933-44), the genetic

material was

thought to be a protein. They worked to determine the biochemical nature of ‘transforming principle’ in Griffith’s experiment. They purified biochemicals (proteins, DNA, RNA, etc.) from the heat-killed S cells to see which ones could transform live R cells into S cells. They discovered that DNA alone from S bacteria caused R bacteria to become transformed. They also discovered that protein –digesting enzymes (proteases) and RNA – digesting enzymes (RNases) did not affect transformation, so the transforming substance was not a protein or RNA. Digestion with DNase inhibit transformation, suggesting that the DNA

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caused the transformation. They concluded that DNA is the hereditary material, but not all biologists were convinced. 34.

Role of microbes in sewage treatment: Microbes play a role in secondary sewage treatment/ biological treatment. The primary effluent is passed into large aeration tanks

where it is constantly agitated mechanically

and air is pumped into it. This allows vigorous growth of useful aerobic microbes into flocs(masses of bacteria associated with fungal filaments to form mesh like structures). While growing, these microbes consume the major part of the organic matter in the effluent. This significantly reduces the BOD (biochemical oxygen demand) of the effluent. BOD refers to the amount of the oxygen that would be consumed if all the organic matter in one liter of water were oxidized by bacteria. The sewage water is treated till the BOD is reduced. Once of the BOD of sewage or waste water is reduced significantly, the effluent is then passed into a settling tank where the bacterial ‘flocs’ are allowed to sediment. This sediment is called activated sludge. A small part of the activated sludge is pumped back into the aeration tank to serve as the inoculum. The remaining major part of the sludge is pumped into large tanks called anaerobic sludge digesters. Here, other kinds of bacteria, which grow anaerobically, digest the bacteria and the fungi in the sludge. During this digestion, bacteria produce a mixture of gases such as methane, hydrogen sulphide and carbon dioxide. 35.

Bt – cotton: 1. It is a transgenic plant produced by cloning Bt genes isolated from Bacillus thuringiensis. 2. It is resistant to cotton boll worms and stem borer which feed on them. 3. Bt genes produce proteins (Crystal Protein – cry I AC, cry II AB) that kills the insects. 4. Hence cry-genes have been introduced in plants to produce crystal proteins as Protoxin (inactive toxin), which is converted to toxins in alkaline medium (i.e. in the gut of insects) and cause death of the insect larva.

36.

a) The parasite that feed on the external surface of the host organism are called ectoparasite. The parasite that live inside the host body at different sites like liver, kidney, lungs, RBCs are called endoparasite b) i) Loss of unnecessary sense organs. ii) Presence of adhesive organs or suckers to cling on to the host. iii) Loss of digestive system. iv) High reproductive capacity

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37.

a) Radioactive waste: Radiation that is given off by nuclear waste is extremely damaging to organism because it cause mutations. At high doses nuclear radiation is lethal but at lower doses it creates various disorders like cancer. Therefore nuclear waste is an extremely pollutant and has to be dealt with utmost caution. Nuclear waste should be stored in a shielded container, buried within the rocks about 500m deep below the earth surface after pre treatment. b) Joint forest Management: Local communities participated in protecting the forest resources. Realising their participation, the Government of India in 1980 has introduced the concept of Joint Forest Management to work closely with the local communities for protecting and managing forest. In return the communities get benefit of various forest products like fruits, gum medicine, rubber and thus the forest can be conservered in sustainable manner. **********

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