· 2015. 9. 18. · marks . marking (a)(i) (ii) -the variation in height for humans is shown in...

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BIOLOGY FORM 5 SPM TRIAL 2007

MARKING SCHEME PAPER 2

QUESTION 1

No Marking Criteria Marks (a) (b) (c ) (i) (ii) (d ) (e) (f) (g)(i) (g)(ii)

Mitosis L, N, K and M K : (Early) anaphase N : Metaphase K : Sister chromatids separate and move towards the opposite poles of the cell N : Chromosomes align at the metaphase plate Cloning is a process to produce a new frog identical to its parent by mitosis. Asexual reproduction. The production of offspring is not involving the process of fertilization. -Mature intestinal cells are able to undergo cell division -have all the necessary factors required for a complete cell division. Species Y The nucleus of the frog is obtained from species Y. TOTAL

1 1 1 1 1 1 2 1 1 2 1 1 1 1 2 1 1 2 1 1 2 ____ 13 ===

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QUESTION 2 No Marking Criteria Marks

(a)

(b) (c) (d) (i)

(ii)

(e) (f)

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) Energy value of the peanut = 20 X 4.2 X 16 Jg-1 2.0 = 672.0 Jg-1 Energy value of the dried prawn = 20 X 4.2 X 4 Jg-1 1.8 = 186.7 Jg-1 The peanut Peanuts contaun more lipids /Lipids have higher energy value than proteins. 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 1 1 1 1 2 1 1 2 1 1 2 1 1 1 2 1 1 1 2


3

TOTAL

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QUESTION 3

Any one

Any one

No Marking Criteria Marks (a)

(b) (i)

(ii) (c) (i).

(ii)

(d) (e) (i) (ii)

Kidney J : Ultrafiltration K : Reabsorption (of glucose) Red blood cells Plasma proteins Both components are large (to move through small pores in the capillary wall and the inner wall of Bowman’s capsule.) 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 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 1 1 1 2 1 1 2 1 1 1 1 1 3 1 1 1 1 1 1 2


4

TOTAL

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12 ===

QUESTION 4

No Marking Criteria Marks (a) ( i) (ii) (b) (c) (d) ( i) (ii) (e)

Follicle stimulating hormone / FSH To stimulate the formation of follicles in the ovary Pt. 1 : If P secretion is reduced, Y is inhibited. Pt. 2 : Ovulation is delayed / does not occur

Or Pt. 3 : If P secretion is excessive, secretion of Y is stimulated. Pt. 4 : Inhibits X, no follicle development / ovulation is hastened The structure T shrinks. The size of structure T is smaller than its size on 20th day. Hormone Q : Progesterone Structure T : Corpus luteum 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. 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 2 1 1 1 1 2 1 1 1 1 2 1 1 2 1 1


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

1 3 ---- 12

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QUESTION 5

T T t t

T t

T t

TtT t

T T T t T t t t

No Marking Criteria Marks

( a ) ( b )

( c ) ( d )

P generation : Gametes

K generation :

Gametes L generation :

M : Meiosis N : Fertilisation Genotypic ratio : 1 TT : 2 Tt : 1 tt Phenotypic ratio : 3 tall : 1 dwarf Mendel’s Law of Segregation :

1 1 1 1 1 5 1 1 2 1 1 1 1 2


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- 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.

TOTAL

1 1

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QUESTION 6


(a)(i)

(ii)

- 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

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

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(b) (i)

(ii)

(c )

- 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.

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.

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

Total=4 1 1 1 1

4 1 1 1 1 1 1 1 1

6

20


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(a)

(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 102C 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

1 1 1 1 1 1

Total=6 1 1

QUESTION 7


9

(c)

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.

- 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 1 1 1 1 1 1 1

Total=11 1 1 1

Total=3

20 marks


10


11

8(a) (i)

(a)(ii)

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-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

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 1 1 1

4 1 1 1 1 1 1 1

6


12

8(b)

The first coloniser are the plankton and algae. These species are usually brought in by muddy feet of birds and other animals that visit the pond. The phytoplankton and algae photosynthesise and provide food for the zooplankton. When these organisms die and decompose, there is more organic matter in the pond. These organic matter provides nutrients for growth of submerged plants. Submerged plants such as Hydrilla and Elodea are now found in the pond. They can photosynthesise and spread rapidly by vegetative propagation. When the submerged plants die, they sink to the bottom. They are decomposed and the humus layer becomes thicker. Soil is also eroded into the pond and the pond becomes shallower. The conditions become unsuitable for submerged plants but more favourable for floating plants. The seeds are usually brought in by birds and animals that use pond. The floating plants such as Lemna, Eichornia and Nymphaea now grow in the pond. The floating plants cover a large area of the surface water and reduce the amount of sunlight to submerged plants. The submerged plants die, decompose and more humus is formed. As the pond becomes more shallow and fertile, the floating plants are gradually replaced by emergent plants. Sedges, for example, Cyperus and Fimbristylis are found on the edge of the pond. As more plants die and decompose, the pond becomes even more shallow. The floating plants die and sedges and other emergent plants spread from the edge to the middle of the pond. Eventually the pond is filled with soil and becomes drier.

1 1 1 1 1 1 1 1

1


13

Terrestrial herbaceous plant such as Euphorbia hirta, Ageratum conyziodes and other grasses grow in the area. The land becomes drier and more fertile. The herbaceous plants are gradually replaced by shrubs and small trees. Eventually a terrestrial forest is formed.

TOTAL

1 1 1

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20


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QUESTION 9


(a)

Similarities

- plants and humans are exposed to stimuli from the

external environment, such as light, water, chemical, etc.

- these external stimuli stimulates automatic or

involuntary responses in plant and reflex actions in humans,

Differences

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

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

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.

F-Nature of message

P- for plants it is chemical; for human it is both chemical (hormone) and electrical

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

Any 2Fs and 2Ps

1 1

2 1 1 1 1 1 1 1 1 1 1

8

10

QUESTION 9


15

(b) (i)

(ii)

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

- 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.

TOTAL

1 1 1

1 1

4 1 1 1 1 1 1

10

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MARKING SCHEMEQUESTION 2QUESTION 3

AlbinismInheritance of albinismTOTALTOTALTOTAL

SimilaritiesDifferences 10 10

· 2015. 9. 18. · marks . marking (a)(i) (ii) -the variation in height for humans is shown in...

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