Scheme Biology Trial P2(eng)

Mark scheme Bio 2 Trial Pahang 2007

1

BIOLOGY FORM 5 SPM TRIAL 2007 MARKING SCHEME PAPER 2 QUESTION 1 No

Marking Criteria

Marks

(a)

Mitosis

1

1

(b)

L, N, K and M

1

1

(c ) (i)

K :

(Early) anaphase

1

N :

Metaphase

1

K :

Sister chromatids separate and move towards the opposite poles of the cell

1

Chromosomes align at the metaphase plate

1

2

1

1

(ii)

N : (d ) (e)

Cloning is a process to produce a new frog identical to its parent by mitosis.

2

Asexual reproduction. The production of offspring is not involving the process of fertilization.

1 1

2

-Mature intestinal cells are able to undergo cell division -have all the necessary factors required for a complete cell division.

1 1

2

(g)(i)

Species Y

1

(g)(ii)

The nucleus of the frog is obtained from species Y.

1

(f)

TOTAL

2 ____ 13 ===

Mark scheme Bio 2 Trial Pahang 2007

QUESTION 2 No (a)

(c)

(d) (i) (ii)

(f)

Marking Criteria The peanut contains more energy (value) compared todried prawns Rise in temperature of the water ( 0C ) : Peanut : 16 Dried prawn : 4 ( Both must be correct)

(b)

(e)

2

Marks 1

1

1

1

Energy value of the peanut = 20 X 4.2 X 16 Jg-1 2.0 = 672.0 Jg-1

1

Energy value of the dried prawn = 20 X 4.2 X 4 Jg-1 1.8 = 186.7 Jg-1

1

The peanut

1

Peanuts contaun more lipids /Lipids have higher energy value than proteins.

1

1. Not all the energy released during the burning of the food is absorbed by the water; some is lost in the form of heat to the surroundings. 2. Some of the energy is absorbed by the boiling tube. 3. The food may not be completely burnt, especially the centre. ( Any two ) 1. Water in the boiling tube must be stirred to ensure that the heat is distributed evenly. 2. (The food must be oxidised completely by) making sure the flame does not extinguished too quickly. 3. The distance between the food and the boiling tube must not be too far. 4. Make sure the thermometer does not touch the bottom of the test tube. ( Any two )

1

1

2

2

2

1 1 1

2

1 1 1

2

Mark scheme Bio 2 Trial Pahang 2007

3

----12 ===

TOTAL

QUESTION 3 No

Marking Criteria

Marks

(a)

Kidney

1

1

(b) (i) (ii)

J : Ultrafiltration K : Reabsorption (of glucose)

1 1

2

(c) (i).

Red blood cells Plasma proteins

1 1

2

Both components are large (to move through small pores in the capillary wall and the inner wall of Bowman’s capsule.) 1

1

(ii)

Pt 1 : The filtrate flows from part J to the proximal tubule, where Pt 2 : a large volume of water is reabsorbed Pt 3 : all the glucose and amino acids are reabsorbed Pt 4 : more water is reabsorbed Pt 5 : the filtrate in the Loop of Henle is more concentrated Osmotic blood pressure decrease

(d)

(e) (i) (ii)

1 Any one 1 Any one

Pt 1 : Osmoreceptor in the hypothalamus is less stimulated, less ADH hormone is secreted. Pt 2 : The distal tubule and the collecting duct are not permeable to water. Pt 3 : Less water is absorbed in the blood. Pt 4 : A large amount of urine is produced, making it dilute. (Any two)

1

3

1

1

1 1 1 1

2

Mark scheme Bio 2 Trial Pahang 2007

4

TOTAL ----12 ===

QUESTION 4 No (a) ( i) (ii) (b)

Marking Criteria

Marks

Follicle stimulating hormone / FSH

1

To stimulate the formation of follicles in the ovary

1

Pt. 1 : If P secretion is reduced, Y is inhibited. Pt. 2 : Ovulation is delayed / does not occur

1 1

2

Or Pt. 3 : If P secretion is excessive, secretion of Y is stimulated. Pt. 4 : Inhibits X, no follicle development / ovulation is hastened (c) (d) ( i) (ii)

(e)

1 1

2

The structure T shrinks. The size of structure T is smaller than its size on 20th day.

1

1

Hormone Q : Progesterone Structure T : Corpus luteum

1 1

2

Pt.1 : On the 16th day, T is formed, hormone Q is secreted. Pt 2 : On the 24th day, T degenerates, the level of hormone Q declines.

1

Pt. 1 : The pituitary gland produces FSH to stimulate the development of follicles in the ovary. Pt. 2 : The follicle secretes oestrogen to repair the uterine wall.

1 1 1

2

Mark scheme Bio 2 Trial Pahang 2007

5

Pt. 3 : After the 14th day, the pituitary produces LH that causes ovulation.

1

---12 ===

TOTAL

QUESTION 5 No (a)

Marking Criteria tt

1

Gametes

T

t

1

K generation :

Tt

Gametes

T

t

T

TT

Tt

Tt

L generation : (b)

(c)

Marks

TT

P generation :

1

M : Meiosis N : Fertilisation Genotypic ratio :

3

t

tt

1 1

5

1 1

2

1

1

1 TT : 2 Tt : 1 tt 1

Phenotypic ratio :

3 tall : 1 dwarf 1

(d)

Mendel’s Law of Segregation :

2

Mark scheme Bio 2 Trial Pahang 2007

6

- The members of each pair of alleles separate or segregate during the formation of gametes. - Only one allele can be carried in a single gamete. 1 TOTAL

QUESTION 6 No (a)(i)

Marking Criteria -

The variation in height for humans is shown in Diagram 7.1 It is continuous variation /normal distribution It has many intermediate values between the highest and the shortest in the population. The characters are quantitative The variation in height for pea plant its shown in Diagram 7.2 It is a discontinuous variation / discrete distribution There are only two categories of variation – either short or tall; there are no intermediate values in between them. The characters are qualitative

1 ----11 ===

Marks

1 1 1

1 1 1

(ii) The continuous variation shown in Diagram 7.1 is - t he result of the combined effects of many genes. - Environmental factors also affects the way in which the genes express themselves. The continuous variation shown in Diagram 7.2 is

1 1

Mark scheme Bio 2 Trial Pahang 2007

-

7

the result of the effect of one or only a few genes. It is caused by genetic factors and also by the mutation of genes and chromosomes.

(b) (i)

1 1 Total=4

(ii) -

Albinism It is a genetic disorder due to genetic mutation. It causes a complete lack of pigment in the eyes, hair and skin. Inheritance of albinism An albino child has a homozygous genotype with two recessive alleles (for the absence of pigmentation.) In sexual reproduction, two heterozygous parents for the genes give rise to a 25% of their child may inherit one recessive( mutant) allele from each parent.

1 1

1 1

4 (c )

The importance of variation - Variation provides new genetic material for the survival of the fittest, - e.g. the mutated genes of the black peppered moth - Variation prepares a species to survive when there are changes in the external environment, like after a volcanic eruption, or in global warming; - e.g. the black peppered moths survive well in a soot-covered environment. - A population with a varied genotypes or genotypes is useful in spreading the particular species over a wider range of habitats; - e.g. the house sparrow. - Produced phenotype/physical differences among individuals. - E.g. No human are alike eventhough they are identitical Any 6 TOTAL

1 1 1 1 1 1 1 1 6 20

Mark scheme Bio 2 Trial Pahang 2007

8

QUESTION 7 No (a)

Marking Criteria -

-

(b)

-

50 maize seeds are planted in a nursery bed. The seeds are given the same condition – the same amount of light, water and minerals On day 1, three maize seeds are removed from the nursery bed and heated at 102°C until their combined mass becomes constant. The average dry mass of each maize seed is determined. On day 3, three maize seeds (or seedling, if they have germinated) are taken out and their average dry mass is determine in the above step (On day 1). Three seedling are again removed at every interval of two day (on day %, 7, 9 and so on) and their average dry mass is determined. Changes in the average dry mass of a maize plant are recorded in the form of a table. The growth curve of the maize plant has a sigmoid shape For the period of time from A to B, the dry mass of

Marks 1 1 1

1 1 1 Total=6 1 1

Mark scheme Bio 2 Trial Pahang 2007

-

9

the plant decreases. This is because the stored food in the seed is oxidised to produce energy for germination. From B to C, leaves have emerged and the young plant begins to make food by photosynthesis. The food is used to make plant tissues. This cause the growth rate to increase. When the maize plant is near maturation, growth slows down and the curve is less steep(CD) During the period from D to E, the plant has reached maturity. The rate of photosynthesis Is equal to the rate of respiration. Hence, there is no more increase in the dry mass of the plant. Growth rate equals zero. When the plant are old, there will be a decrease in the dry mass of the plant (EF). This is because flowers, fruits and the older leaves fall off. The growth rate is negative.

1 1 1 1 1 1 1 1 1 Total=11

1 (c)

-

The dry mass of an organism is its mass after all its water content has been removed. It is the mass of real tissues in the organism Unlike fresh mass, dry mass is not affected by changes in the water content in the organism. TOTAL

1 1 Total=3 20 marks

Mark scheme Bio 2 Trial Pahang 2007

10

Mark scheme Bio 2 Trial Pahang 2007

11

8(a) (i) Biodiversity is important for several reasons: F- it provides humans with necessities of life P- is a resource for food /timber to build shelter / as a fuel/fibers for clothing F- many plant species are original sources of pharmaceutical drugs/medicines. P- New commodities, for example, new crop plants or medicinal materials could be developed using the gene pool from wild species in the forests. F- F-Allow for biological control to maintain stable population P- Regulate climatic conditions, biogeochemical cycles, prevent flooding F- Natural ecosystems and species in the wild are beautiful P- there is much pleasure to be derived from unspoilt natural environment. F- Ecotourism P-could provide income for some countries Any 2F and 2P

1 1 1 1 1 1 1 1 1 1 4

(a)(ii)

Waste materials from households - rich in organic matters,bacteria and microorganism - (in oxidation pond) the sewage is decomposed by (millions0 of aerobic bacteria (in the presence of oxygen) - Decomposed sewage /sludge settled to the bottom of the pond - Fermentation takes place at (sedimentation tanks) - Using anaerobic bacteria - Produce methane/carbon dioxide/minerals - Digested sludge used as fertilisers Any 6

1 1 1 1 1 1 1 6

Mark scheme Bio 2 Trial Pahang 2007

12

QUESTION 9 No

Marking Criteria

(a)

Similarities

Marks

-

plants and humans are exposed to stimuli from the external environment, such as light, water, chemical, etc.

1

-

these external stimuli stimulates automatic or involuntary responses in plant and reflex actions in humans,

1 2

Differences F-rate of response P-is slow in plants, is fast in humans

1 1

F-Duration of response P-for plants response lasts longer if the stimulus stays the same; it involve either a rapid response for humans.

1

F-Location of response P-for plants, a response takes place at the region just below the shoot tip or above the root tip; for humans response takes place in one or more specific effectors in different parts of the body.

1

1 1

F-Nature of message P- for plants it is chemical; for human it is both chemical (hormone) and electrical

1

F-Type of response P- for plants it is a growth movement caused by cell division and cell elongation; for humans it involves muscular contraction or secretions from glands

1

1

1

Any 2Fs and 2Ps 8 10

Mark scheme Bio 2 Trial Pahang 2007

(b) (i)

13

A drug is any chemical externally administered to the human body and it: -

(ii)

affects the chemical reactions of the human body is used to prevent, diagnose, treat or relieve symptoms of a disease - also alters a person’s mood or body function that can be habit-forming or addictive - Drug abuse is the misuse(wrongly used) or overuse(overdose) of any drug or medication, including alcohol causing addiction and wrecking lives. - A drug becomes a medicine if it is prescribed by medical doctors to cure diseases. Any 4 Some causes of drug abuse: -

-

seeking pleasure; e.g. heroin addiction starts off with a desire for pleasure. To enhance physical performance; e.g. taking anabolic steroids to increase sports performance or amphetamine in order to stay awake more hours. Influenced by bad company – e.g. Influenced by drug addicts. Taking ‘club drugs – e.g. taking ecstasy pills, which is a stimulants and hallucinogen used to improve mood and to maintain energy, often for all-night dance parties. Out of curiosity – adolescents are often curious and want to try. Peer group pressure and influence.

1 1 1 1

1 4

1 1 1 1 1 1 10

TOTAL

20