Biology Paper 2 16 Sample Ques t

1

2010 Pyramid Projections©

2010 Pyramid Projections 001 BIOLOGY PAPER 2

1. Examine the diagram below carefully and use it to answer the

questions that follow.

(a) Name the parts labelled X, Y and Z

(3mks)

(b) State the substance by which the part labelled W is made up of

(1mk)

(c) Name the process by which mineral salts move into the structure

labelled X (1mk)

(d) Explain what happens to a red blood cell when placed in distilled

water (3mks)

2. (a) Name two sites where gaseous exchange takes place in an aquatic

plant. (2mks)

(b) The diagram below represents the gills of a bony fish. Study it and

answer the questions that follows.

(i) Name the parts labelled A, B and C.

(3mks)

(ii) State the function of the part labelled A

(1mk)

(iii) Explain how the part labeled C is adapted to perform its function.

(2mks)

3. (a) Reproduction is a characteristic of living things. State two

importance of it in living

things

(2mks)

(b) (i) At what stage of mitosis do chromosomes replicate to form

daughter

chromatids.

(1mk)

2


(ii) State three differences between mitosis and meiosis

(3mks)

(c) State two ways in which flowers prevent self –pollination.

(2mks)

4. In a family with four children, three were found to have normal skin

pigmentation while one was an albino. Using letter A to represent gene

for normal skin pigmentation and a to represent gene for albinism

(a) What are the genotypes of the parents?

(2mks)

(b) Work out the genotype of normal pigmented children and the

albino child.

Show your working.

(4mks)

(c) What is the probability that the seventh child will be an albino?

(1mk)

(d) What is meant by the term test cross in genetic studies?

(1mk)

5. A student set up an experiment as shown in the diagram below.

(a) What was being investigated in the experiment?

(1mk)

(b) On the diagram below indicate the expected results after three

days. (2mks)

(c) Why was it necessary to have wet cotton wool in the container?

(1mk)

(d) What is the role of each of the following to a germinating seed?

(i) Oxygen

(2mks)

(ii) Cotyledons

(1mk)

3


(e) Small seeds require light immediately after germination. Explain

(1mk)

6. In an experiment, the energy required by persons of different sizes

were determined, their weights and amount of energy their bodies used

at rest were measured.

The results were as shown in the table below.

Weight of individuals (Kgs) Amount of energy used per kg of body weight per day in KJ

5 300 15 200 25 150 35 130 45 115 55 105 65 100 75 95

(a) Using a suitable scale draw a graph of the amount of energy used

per Kg of body weight per day against the weight of individuals.

(6mks)

(b) (i) From the graph determine the energy requirement of a person

weighing 10Kg (1mk)

(ii) What is the difference in energy requirements between persons

weighing 60 and 70 Kg

(2mks)

(c) Why did individuals with bigger body size require lesser energy per

Kg of body weight than one with smaller size?

(3mks)

(d) Use the graph to determine the energy requirement of an infant

whose body weight is 2.5 Kg.

(2mks)

(e) (i) How would the results differ if the experiment was repeated using

reptiles of equivalent weight as humans instead of the human beings?

(1mk)

(ii) Give a reason for your answer in (i) above

(1mk)

(f) Apart from body weight, which other factors determines the energy

required by an individual

(2mks)

(g) Name the class of food that provide energy to a mammal during

starvation. (1mk)

4


(h) State one function of roughage in a diet of a mammal.

(1mk)

7. Describe how the mammalian heart is adapted to its function

(20mks)

8. Discuss the evidence of organic evolution

(20mks)

Name ………………………..………………………… Index No.

..………………..…….….

School ………………………………………………...

231/2 BIOLOGY Paper 2 (THEORY) Time: 2 Hours 2010 Pyramid Projections.002 Kenya Certificate of Secondary Education (K.C.S.E) 231/2 BIOLOGY Paper 2 (THEORY) Time: 2 Hours INSTRUCTIONS TO CANDIDATES • Write your name, school and index number in the spaces provided above. • Sign and write the date of examination in the spaces provided above. • This paper consists of TWO Sections: A and B. • Answer ALL the questions in Section A in the spaces provided. • In Section B answer question 6 (compulsory) and either question 7 or 8 in the spaces

provided after question 8. FOR EXAMINERS USE ONLY

Section Question Maximum Score Candidate’s Score

A 1

2

3

4

5

8

8

8

8

8

B 6

7

8

20

20

20

TOTAL SCORE 80

This paper consists of 11 printed pages.

Candidates should check the question paper to ensure that all the Pages are printed as indicated and no questions are missing.

5


SECTION A (40 Marks)

Answer ALL questions in this section in the spaces provided.

1. The diagram below represents a generalized cell structure as seen under an

Electron microscope.

a) Name structures labeled A, B and C.

(3 mks)

b) How is structure labeled B adapted to its function.

(2 mks)

c) What difference would be observed between electron micrograph obtained

from a cheek cell of a frog and the one above.

(2 mks)

d) Explain the function of structure labeled D.

(1 mk)

2. The diagram below represents a scheme diagram of movement of water from

soil through leaves of a flowering plant into the atmosphere.

a) (i) Name parts labeled Q, R and S.

(3 mks)

C

A

D

B

Leaf I

S R Q

II

III

IV

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(ii) How is structure labeled R adapted to its function.

(2 mks)

b) On the diagram draw alternative site for water loss through leaf.

(1 mk)

c) Identify process (III)

(1 mk)

d) How is structure T adapted to its function.

(1 mk)

3. The diagram below shows some of the processes that take place in a female

reproductive system.

a) Name process labeled;

(1 mk)

I:

b) Name structures labeled;

(2 mks)

T:

R:

c) Identify hormones responsible for formation of structures:-

(2 mks)

T:

R:

d) Explain what leads to process at II.

(3 mks)

4. Broad and thin lips in humans are characteristics that are inherited, when a

homozygous broad lipped man is crossed with a homozygous thin lipped woman;

all the children in the family are broad lipped.

In a particular family, a woman that is heterozygous for broad lips is married

to a man whose parents were both thin lipped, using letter B to represent genes for

lips.

a) Work out the genotypic ratio of the children in that family.

(6 mks)

b) What is the phenotypic ratio of the children in (a) above.

(1 mk)

c) Differentiate between gene mapping and sequencing of gene.

(1 mk)

5. The diagram below represents a diagram of a limb girdle.

Ovary

x K

T

7


a) Identify parts labeled K, L and M.

(3 mks)

b) (i) Identify part labeled x

(1 mk)

(ii) How is part labeled x adapted to its function.

(1 mk)

c) Identify part labeled Z and hence state its significance.

(1 mk)

d) Name part labelled y.

(1 mk)

e) How is joint articulating at y adapted to its function.

(1 mk)

SECTION B (40 Marks)

Answer question 6(compulsory) in the spaces provided and either question 7 or 8 in

the spaces provided after question 8.

6. In an experiment to investigate the effect of heat on germination of seeds, 12

bags each containing 60 pea seeds were placed in a water bath maintained at 850C.

After every two minutes a bag was removed and seeds contained in it planted.

The number that germinated was recorded. The procedure used for pea seeds

was repeated for wattle seeds. The results were as shown in the table below.

Number of seeds that germinated Time(min) Pea seeds Wattle seeds 0 2 4 6 8 10 12 14 16 18 20 22

60 60 48 42 34 10 2 0 0 0 0 0

0 0 0 2 28 36 40 44 46 48 49 47

a) Using a suitable scale and on same axes, draw graphs of number of seeds

that germinated against time in hot water for each plant.

(6 mks)

b) (i) At what time would number of seed that germinated for each plant be same. (1

mk)

y

z

M L

8


(ii) How many wattle seeds would have germinated if the 13th bag was

available and was removed and seeds contained in it planted at 24 minutes.

(1 mk)

c) Explain why the ability of pea seeds to germinate declined with time of

exposure to heat.

(2 mks)

d) Explain why the ability of the wattle seeds to germinate improved with

time of exposure to heat.

(2 mks)

e) Account for the shape of the graph for the wattle seeds which germinated

between 20 – 24 min.

(2 mks)

f) Some of the pea seeds were allowed to germinate and placed in a large

airtight flask and left for four days.

(i) Suggest the expected changes in the composition of gases in the flask on

the fifth day.

(2 mks)

(ii) Give reasons for your answer in (f) (i) above.

(1 mk)

g) Name three factors other than those investigated in a) above which would

affect dormancy.

(3 mks)

7. a) Name two processes by which flowering plants excrete products, and for

each process, state two waste products that are eliminated.

(6 mks)

b) Explain the roles of the

(i) Liver

(ii) Kidneys in eliminating excess amino acids from the human body.

(14 mks)

8. Describe the structure and function of various parts of the mammalian skin.

(20 mks)

NAME: ……………………………………………………………………… INDEX NO:…………………….…… SCHOOL: .……………………………………………………………………………………………………….……

9


BIOLOGY PAPER 2 TIME 2 HOURS

2010 Pyramid Projections.003 Kenya Certificate Of Secondary Education

231 / 2

BIOLOGY PAPER 2

INSTRUCTIONS TO CANDIDATES

� Write your name and Index number in the space provided above. � Sign and write the date of examination in the spaces provided above. � This paper has two sections A and B. � Answer ALL the questions in section A in the spaces provided on the

question paper. � In section B answer question 6(compulsory) and either question 7 or 8

in the spaces Provided after question 8.

For Examiner’s Use Only.

SECTION QUESTIONS MAXIMUM

SCORE CANDIDATES

SCORE

A

B

1 8 2 8 3 8 4 8 5 8 6 20 7 20 8 20

TOTAL SCORE 80

SECTION A Answer ALL questions I this section in the spaces provided. 1. The diagram below represents a blood clotting formed in the body of a

mammal.

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(a) Name the cells labelled S and T.

(2 Marks)

S. …………………………………………………………

T. …………………………………………………………

(b) State the function of the cell labelled S in the body of a mammal.

(1 Mark)

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(c) Describe how the fibrin threads are formed.

(3 Marks)

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(d) Give TWO adaptations of cell labelled T to its functions.

(2 Marks)

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2. In a plant breeding experiment, a tall pea plant was crossed with a dwarf

pea plant. All the F1 generation plants were tall. The F1 generation plants

were selfed that resulted in 325 dwarf plants out of 898 plants.

(a) (i) How many plants in F2 generation were tall?

(1 Mark)

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(ii) What was the dominant character in the cross above?

(1 Mark)

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(b) Using letter T to denote the gene for height, work out the genotypes of F2

generation (3 Marks)

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(c) State the biological importance of self-incompatibility of pollen grains on

the stigma of the same

plant.

(2 Marks)

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(d) What is heterostyly?

(1 Mark)

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3. The diagram below represents a structure used for gaseous exchange in a

woody plant.

(a) Name the part labelled A and B

(2 Marks)

A: .......................................................................................

B: ……………………………….......................................

(b) Name the gases marked by arrows X and Y

(2 Marks)

X: .....................................................................................

Y: .....................................................................................

(c) Give the function of the part labelled B

(1 Mark)

13


…………………………………………………………………………

……………………………..

(d) (i) Name the physiological process that results in production of gas X in

the plant tissues. (1 Mark)

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(ii) Write down a word equation to represent the physiological process

named in (d) (i) above in a

plant cell.

(1 Mark)

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(e) Why does low oxygen concentration in the soil result in reduced mineral

ion absorption by root hairs

of plants?

(1 Mark)

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4. The diagram below represents some components of a light microscope.

(a) Name the parts labelled A and B

(2 Marks)

A: ..................................................................

14


B: ...................................................................

(b) State the functions of the parts labelled E and F

(2 Marks) E:

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

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

F:

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

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

(c) Give the formula used to calculate magnification in a light microscope.

(1 Mark)

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(d) Give a reason for each of the following procedures when preparing

sections to be observed under a

light microscope.

(i) Cutting thin sections

(1 Mark)

…………………………………………………………………………

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(ii) Staining the sections

(1 Mark)

…………………………………………………………………………

……………………………..

(iii) Place the cut sections in water

(1 Mark)

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5. The diagram below represents a maize seedling.

15


(a) Name the type of germination exhibited by maize.

(1 Mark)

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b) Name the parts labelled P and R

(2 Marks)

P: ……………………………………...................................

R: ……………………………………...................................

(c) Give two functions of the part labelled R (2

Marks)

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(d) Give Two characteristics of the cells obtained from the parts labelled S

(2 Marks)

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(e) State the role of the part labelled Q during the process of germination.

(1 mark)

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Answer question 6 (compulsory) in the spaces provided and either

question 7 or 8 in the

spaces provided after question 8

6. The approximate number of ticks per cattle in a certain farm before and

after spraying with a constant concentration of a specific acaricide was

determined for a period of 20 years. The spraying was done once per month.

The results were as shown below.

TIME IN YEARS 0 1 3 6 10 15 18 20

NUMBER OF TICKS PER CATTLE 200 120 40 20 19 25 45 90

(a) On the grid provided, plot a graph of number of ticks per cattle against

time in years. (6 marks)

(b) What was the number of ticks per cattle after two years?

(1 mark)

…………………………………………………………………………

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(c) Account for the changes in the number of ticks per cattle between

(i) 0 to 10 years

(2 marks)

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(ii) 15 to 20 years

(3 marks)

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17


…………………………………………………………………………

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(d) Explain two disadvantages of using acaricides in tick control

(2 marks)

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(e) State three alternative methods that would have been used instead of

acaricides in the control of

ticks.

(3 marks)

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(f) Name the appropriate method used to estimate the number of ticks per

cattle. (1 mark)

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(g) (i) Name the class of arthropoda to which the tick belongs .

(1 mark)

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(ii) Give one reason for your answer in f (i) above

(1 mark)

18


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8. How are the xerophytes adapted to live in their habitats?

(20 marks)

9. Describe how excretion takes place in the mammalian kidneys?

(20 marks)

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Name ………………………..…………………………

Index No. ..………………..………………..

School ………………………………………………...

231/2 BIOLOGY Paper 2 Time: 2 Hours 2010 Pyramid Projections 004 Kenya Certificate of Secondary Education (K.C.S.E) 231/2 BIOLOGY Paper 2 Time: 2 Hours INSTRUCTIONS TO CANDIDATES • Write your name and index number in the spaces provided above. • This paper consists of two sections: A & B. • Answer ALL the questions in Section A in the spaces provided. • In section B, answer question 6(compulsory) and either question 7 or 8 in

the spaces provided after question 8.

19


FOR EXAMINER’S USE ONLY

Section Question Maximum score Candidates score

A 1

2

3

4

5

8

8

8

8

8

B 6

7

8

20

20

20

TOTAL SCORE 80

This paper consists of 12 printed pages. Candidates should check the question paper to ensure that all the

Pages are printed as indicated and no questions are missing. Section A (40 Marks)

Answer all questions in this section in the spaces provided 1. a) Two type of dental formulae are shown below . Giving one reason

for each case, suggest which one belongs to the sheep and dog

(4 mks)

Dental formulae Animal Reason

i) i 3/3, C 1/1, pm 4/4 , m

2/3

ii) i 0/3, c 0/1, pm 3/3 , m

3/3

b) State two ways in each case how the animal represented by the

dental formulae above are suited to their modes of feeding.

Animal (i)

(2 mks)

Animal (ii)

(2 mks)

2. a) Below is a nucleotide strand

(i) Identify the type of nucleic acid strand

(1 mk)

G

20


(ii) Give a reason for your answer in a (i)

(1 mk)

(iii)Write down the complimentary base sequence in the messenger

RNA that is formed from the above strand

(1 mk)

b) State one characteristic of mutation

(1 mk)

c) Grace and John had four children, three were found to have normal

skin pigmentation while one was albino. Using letter A to represent

gene for normal pigmentation and “a” to represent gene for albinism (i)

What are the genotypes of the parents? (1 mk)

(ii) Work out the genotype of the albino child

(3 mks)

The diagram below shows a set up that was used to demonstrate a type

of respirations {3mks}

a) State the type of respiration that was being demonstrated

(1 mk)

b) (i)Give a reason for your answer in (a) Above

(1 mk)

(ii) State the observation made after 6 hours on the thermometer

reading in flask A and B. (2 mks)

Flask A

Flask B

c )Account for the observation in the flask A and B

Flask A.

(3 mks)

Flask B

(1 mk)

4 a) Explain how each of the following factors affect living organism

within an ecosystem

Sugar sol +

Boiled yeast

Thermometer

Cotton wool

Thermos flask

Sugar soln+ yeast

.

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(i) Predators

(2 mks)

(ii) Light

(2 mks)

(iii) Competition

(2 mks)

b) Explain the role of each of the following features on Xerophytes

(i) Succulent stems and leaves

(1 mk)

(ii) Short life cycle

(1 mk)

5 The diagram below shows three different types of neurones along a

reflex arc

a) Identify the neuron labelled 1 ,2 and 3

(3 mks)

b) Using arrows show the direction of impulse transmission on the

diagram (1 mk)

c) Name the part of the spinal cord where the cell bodies of neurone 2

and 3 are located (1 mk)

d) Describe the transmission impulse across the part labelled P

(3 mks)


Answer question 6 (compulsory) in the spaces provided and either question 7 or 8

in the spaces provided after question 8

6 In an experiment a group of female locusts were fed on excess amount

of food for 20 days from the last moulting stage. It was observed that

they laid eggs between day 12 and 14 and between day 18 and 20 of

their adult life. The average dry weight of faeces and fresh weight of

the locusts was taken at intervals of two days and recorded. The results

of the experiments are shown below:-

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Day of adult life 2 4 6 8 10 12 14 16 18 20

Average dry weight

of faeces (mg)

250 480 610 740 850 750 540 830 720 620

Average weight of

locusts (mg)

530 750 850 950 1070 1160 840 1020 1120 820

a) Using same axes, draw graphs of weight of faeces and locusts

against time (8 mks)

b) From your graph :-

(i) Determine the average weight of the locust on the 9th day

(1 mk)

(ii) Explain the shape of the graph of the average dry weight of faeces

between 10th and 14th day

(2 mks)

c) Explain the relationship between:-

(i) Food consumption and body weight

(3 mks)

(ii) Egg production and food consumption

(3 mks)

d) State two possible consequences of reducing the amount of food by

half of that required by each locust through out the study period

(2 mks)

e) Proteins and carbohydrates are two nutrients that were provided in

the diet of the locust. State one major role of each in the body of the

locust.

Protein

(1 mk)

Carbohydrates

(1 mk)

7 a) Explain how various environmental factors increase the rate of

transpiration (16 mks)

b) What is the significance of transpiration to plants

(4 mks)

8 Describe how natural selection brings about adaptation of a species of

a living organism to its environment.

(20 mks)

Name: . ………………………………………………….School:……………………………

23


Index No. …………………………………….. 231/ 2 Biology Theory Paper 231/ 2

2010 Pyramid Projections 005 (Kenya Certificate of Secondary Education (K.C.S.E) 231/ 2 Biology Theory Paper 231/ 2 INSTRUCTIONS TO CANDIDATES: � Answer ALL questions in section A by filling in the spaces provided

� In section B, answer question 6 (compulsory question) and any other one question from the remaining two questions. (i.e 7 or 8)

FOR EXAMINER USE ONLY Section A Questions Maximum score Candidates score A 1

2 3 4 5

6 20 7 20 8 20 Total score 80

This paper consists of 12 printed pages.

Candidates should check the question paper to ensure that all the Pages are printed as indicated and no questions are missing.

SECTION A (40 MARKS) 1. The diagram below represents an experimental set up to investigate

effects of gravity and light on the growing seedling.

24


a) (i) Draw a diagram of the seedling to experiment the expected

results after three days

(2mks)

(ii) Explain the appearance of the seedling in a (i) above.

(4mks)

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b) Suggest a control experiment for the gravity in this experiment.

(Imk)

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c) State one importance of the type of response shown in the

experiment above. (Imk)

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2.

a) Give the reason why the following must be regulated in the donkey.

i. Temperature.

(2mks)

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ii. PH.

(2mks)

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b) Describe how the level of blood sugar in man is maintained.

(4mks)

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3. Three jars were set up as shown below:-

Four (4)drops of phenol indicator were added to each jar. The phenol

indicator was red at the beginning of the experiment. Phenol changes

26


from orange red to yellow at PH 6.8. After 3 hours in sunlight, the

following results were obtained:

Jar

Colour of indicator

P Red Q

Yellow

R Orange red a) Give two ways of bringing a colour change from orange red to yellow

in jar R. (2mks)

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b) Account for the colour changes in jar:

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i. P

(3mks)

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ii. Q

(3mks)

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4. A bull with coat of red colour was crossed with a cow of white colour

coat.

The calf produced had a coat of roan colour.

a) Explain the appearance of a roan coat colour on the calf.

(Imk)

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……………

b) The roan colour after attaining maturity was black crossed with a bull

of red coat colour. Work out the phenotypic ratio of the offsprings

produced (4mks)

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…………………………………………………………………………………

……………………………………………………………………

c) State how genetics can be used in the field of Agriculture.

(Imk)

…………………………………………………………………………………

…………………………………………………………………………………

…………………………………………………………………………………

……………………………………………….…………………………………

……

d) State two sources of discontinuous variation.

(2mks)

…………………………………………………………………………………

…………………………………………………………………………………

…………………………………………………………………………………

28


…………………………………………………………………………………

……

5. The diagram below shows a section of the human alimentary canal.

Study it and answer the questions that follows:

a) Name the parts labeled:-

S……………………………………..

U……………………………………….

(2mks)

b) Explain the functions of the contents stored in T in the digestions.

(2mks)

…………………………………………………………………………

…………………………………………………………………………

…………………………………………………………………………

…………………………………………………………………………

…………………………………………………………………………

…………………………………………………………………………

………………………………………………………………………

…………………………………………………………………………

……………………………

i. Name two enzymes contained in the substance secreted by S.

(2mks)

…………………………………………………………………………

…………………………………………………………………………

…………………………………………………………………………

…………………………………………………………………………

….…………

ii. State the functions of the enzymes named in c(i) above.

(2mks)

29


…………………………………………………………………………

…………………………………………………………………………

…………………………………………………………………………

…………………………………………………………………………

……………

6. SECTION B. Answer question 6 (compulsory question)

The above graph shows growth of two organisms. A rat and a grasshopper

over a period of time.

a) Identify the growth pattern represented by graphs:-

A………………………………………………………

B………………………………………………………

(2mks)

b) Account for the shape of graph B.

(4mks)

…………………………………………………………………………

…………………………………………………………………………

…………………………………………………………………………

…………………………………………………………………………

…………………………………………………………………………

30


…………………………………………………………………………

…………………………………………………………………………

…………………………………………………………………………

…………………………………………………………………………

…………………………………………………………………………

…………………………………………………………………………

…………………………………………………………………………

…………………………………………………………………………

…………………………………………………………………………

…………………………………………………………………………

………………………

c) Name the hormone responsible for the process that occurs between M

and N, which facilitates increase in the body size.

(Imk)

…………………………………………………………………………

…………………………………………………………………………

…………………………………………………………………………

…………………………………………………………………………

……………

d) Account for the shape of graph A between

i. P and Q.

(3mks)

…………………………………………………………………………………

…………………………………………………………………………………

…………………………………………………………………………………

…………………………………………………………………………………

…………………………………………………………………………………

…………………………………………………………………………………

…………………………………………………………………………………

…………………………………………………………………………………

…………

ii. Q and R.

(4mks)

…………………………………………………………………………………

…………………………………………………………………………………

…………………………………………………………………………………

…………………………………………………………………………………

…………………………………………………………………………………

…………………………………

31


e)

i. Name the type of fertilization that is shown in rats.

(Imk)

…………………………………………………………………………………

…………………………………………………………………………………

…………………………………………………………………………………

…………………………………………………………………………………

….…

ii. Give two advantages of the type of fertilization named in e (i) above.

(2mks)

…………………………………………………………………………………

…………………………………………………………………………………

…………………………………………………………………………………

…………………………………………………………………………………

……

f)

i. Name the type of cell division that leads to formation of spermatozoa in

man. (Imk)

…………………………………………………………………………………

…………………………………………………………………………………

…………………………………………………………………………………

…………………………………………………………………………………

……

ii) Name two chromosomal events that occur in the type of cell division

named in

f (i) above.

(2mks)

…………………………………………………………………………………

…………………………………………………………………………………

…………………………………………………………………………………

…………………………………………………………………………………

……

ESSAY S

7. Describe the importance of a balanced diet in children.

(20mks)

…………………………………………………………………………………

…………………………………………………………………………………

…………………………………………………………………………………

32


…………………………………………………………………………………

…………………………………………………………………………………

…………………………………………………………………………………

…………………………………………………………………………………

…………………………………………………………………………………

…………………………………………………………………………………

…………………………………………………………………………………

…………………………………………………………………………………

…………………………………………………………………………………

…………………………………………………………………………………

…………………………………………………………………………………

………………………

8. How is the gaseous exchange system of a mammal adapted to perform its

functions? (20mks)

………………………………………………………………………………………………………………………………………………………………………………………………………………………… NAME ……………………………………………………….…… INDEX NO……………..….…… SCHOOL…………………………………………………..…… 231/2 BIOLOGY PAPER 2 THEORY TIME: 2 HOURS

2010 Pyramid Projections.007 Kenya Certificate of Secondary Education

231/2 BIOLOGY PAPER 2


33


� Write your name and index number in the spaces provided above. � This paper consists of 2 sections A and B � Answer all the questions in section A in the spaces provide. � In section B, answer question 6 (Compulsory) and either question 7

or 8 in the spaces provided after question 8

For Examiners Use Only

Section Question Maxi. Score Candidates Score

A

1 8

2 8

3 7

4 9

5 8

B

6 20

7 20

8 20

TOTAL 80

1. A student set up the following apparatus for an experiment.

(a) The student boiled the yeast solution before the experiment. Explain.

(1mk)

…………………………………………………………………………

…………………………………………………………………………

…………………………………………………………………………

34


…………………………………………………………………………

……

(b) The mixture of yeast suspension and glucose solution was cooled to

about 370 C. Explain.

(1mk)

…………………………………………………………………………

…………………………………………………………………………

…………………………………………………………………………

…………………………………………………………………………

……

(c) Why was a layer of oil added to the mixture of glucose and yeast?

(1mk)

…………………………………………………………………………

…………………………………………………………………………

……………………………………………………

(d) State the observations expected in

(i) Tube A

(1mk)

…………………………………………………………………………

…………………………………………………………………………

……………………………………………………

(ii) Tube B

(1mk)

………………………………………………………………………………

………………………………………………………………………………

………………………………………………

(e) Account for the observations in d (i) and (ii) above.

(1mk)

…………………………………………………………………………

…………………………………………………………………………

…………………………………………………………………………

…………………………………………………………………………

35


…………………………………………………………………………

………………………………

(f) (i) Apart from carbon (IV) Oxide and energy, what other products can

be found in tube A?

(1mk)

…………………………………………………………………………

…………………………

(ii) Explain how you can confirm this.

(1mk)

…………………………………………………………………………

…………………………

2. (a) Explain the role of enzymes in living cells.

(1mk)

…………………………………………………………………………

…………………………………………………………………………

……………………………………………………

(b) The graph below shows the effects of temperature on the rate of

reaction of the enzyme

salivary emylase

(i) Account for the change in the curve between C and D.

(1mk)

Temperature (0C)

36


…………………………………………………………………………

…………………………………………………………………………

…………………………………………………………………………

…………………………………………………………………………

…………………………………………………………………………

………………………………

(ii) What does the dotted line represent?

(1mk)

…………………………………………………………………………

…………………………………………………………………………

…………………………………………………………………………

…………………………………………………………………………

…………………………………………………………………………

………………………………

(c) Explain how the following factors affect the rate of enzyme

activity:

(i) Temperature

(2mks)

…………………………………………………………………………

…………………………………………………………………………

…………………………………………………………………………

…………………………………………………………………………

…………………………………………………………………………

…………………………………………………………………………

…………………………………………………………

(ii) Substrate concentration.

(2mks)

…………………………………………………………………………

…………………………………………………………………………

…………………………………………………………………………

…………………………………………………………………………

…………………………………………………………………………

…………………………………………………………………………

…………………………………………………………

37


3. In cats, sex is determined by X and Y chromosomes in the same way as

in humans. One gene for coat colour in cats is present on the X

chromosome but not on the Y chromosome. This gene has two alleles

Orange (B) and black (b) and X chromosome bearing the B allele is

represented by XB and one bearing the b allele by Xb.

Female cats that are homozygous for the Xb allele have black coats;

female cats that are heterozygous have tortoiseshell coats. (Orange with

dark patches).

(a) Give the genotype of

(i) A female cat with tortoiseshell coat

(1mk)

…………………………………………………………………………

…………………………

(ii) A male cat with an orange coat.

(1mk)

…………………………………………………………………………

…………………………

(iii) A male cat with a black coat.

(1mk)

…………………………………………………………………………

…………………………

(b) A black coated male cat is mated with a tortoiseshell coated

female cat. Use a genetic diagram to explain what would be the

expected ratios of the genotypes and the phenotypes of the

kittens that could be produced by this cross.

(5mks)

………………………………………………………………………………

………………………………………………………………………………

………………………………………………………………………………

………………………………………………………………………………

………………………………………………………………………………

………………………………………………………………………………

………………………………………………………………………………

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38


………………………………………………………………………………

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………………………………………………………………………………

………………………………………………………………………………

………………………………………………………………………………

………………………………………………………………………………

………………………………………………

4. (a) What is meant by the term homeostasis?

(1mk)

…………………………………………………………………………

…………………………………………………………………………

…………………………………………………………………………

…………………………………………………………………………

…………………………………………………………………………

………………………………

The figure below shows the body temperature of a person before,

during and after taking a cold bath. The temperature of the bath water

is 220C

(b) For how long was the person in the bath?

(1mk)

…………………………………………………………………………

…………………………

39


(c) Explain why the person’s body temperature fell.

(1mk)

…………………………………………………………………………

………………………………………………………………

(d) Explain the role played by the following in helping to return the

body temperature to normal.

(i) The liver

(2mks)

…………………………………………………………………………

…………………………………………………………………………

…………………………………………………………………………

…………………………………………………………………………

……

(ii) Blood vessels in the skin.

(2mks)

…………………………………………………………………………

…………………………………………………………………………

…………………………………………………………………………

…………………………………………………………………………

…………………………………………………………………………

………………………………

(iii) Muscle of the body.

(2mks)

…………………………………………………………………………

…………………………………………………………………………

…………………………………………………………………………

…………………………………………………………………………

……

5. The diagram shows the internal structure of a leaf

40


A B C

D

E F

(a) Name the parts labeled A, B, C, D, & F

(2mks)

A …………………………………………………

B ………………………………………………

D …………………………………………………

F …………………………………………………

(b) State the functions of the parts labeled A, C, D and F

(4mks)

A

…………………………………………………………………

…………………………

C

…………………………………………………………………

…………………………

D

…………………………………………………………………

………………..………

F

…………………………………………………………………

…………………………

(c) State two structural differences between guard cells and other

epidermal cells. (2mks)

…………………………………………………………………………

…………………………………………………………………………

…………………………………………………………………………

…………………………………………………………………………

41


…………………………………………………………………………

………………………………

6. The figure below shows the changes in volume of air whilst breathing

in and out during a breathing exercise. The letters A to H represents

successive breaths.

From the information given in the above figure,

(a) (i) How much air leaves the lungs each time you breath out

during normal quiet breathing?

(1mk)

…………………………………………………………………

…………………………

(ii) What has the person done to achieve peak X on the graph?

(1mk)

…………………………………………………………………

…………………………

(iii) What is the greatest volume of air that is expelled in a

single, outward breath?

(1mk)

………………………………………………………………………

………………………

(b) State one difference in the flow of the respiratory medium (air

or water) in mammals and fish.

(1mk)

………………………………………………………………………

………………………

42


(c) State one reason why exercise cause an increase in breathing

rate. (1mk)

………………………………………………………………………

………………………………………………………………………

………………………………………………

(d) (i) What happens to breathing rate when a person breathes in

100% oxygen?

(1mk)

…………………………………………………………………………

…………………………

(ii) Suggest what happens in the lungs and blood of the person.

Account for your answer in (i) above?

(2mks)

…………………………………………………………………………

…………………………………………………………………………

……………………………………………………

(e) Distinguish between breathing and respiration.

(2mks)

…………………………………………………………………………

…………………………………………………………………………

…………………………………………………………………………

…………………………………………………………………………

…………………………………………………………………………

………………………………

(f) Describe the breathing mechanism in man during inhalation.

(4mks)

…………………………………………………………………………

…………………………………………………………………………

…………………………………………………………………………

…………………………………………………………………………

…………………………………………………………………………

…………………………………………………………………………

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43


…………………………………………………………………………

…………

(g) Explain the disadvantages of anaerobic respiration over aerobic

respiration.

(6mks)

…………………………………………………………………………

…………………………………………………………………………

…………………………………………………………………………

…………………………………………………………………………

…………………………………………………………………………

…………………………………………………………………………

…………………………………………………………………………

…………………………………………………………………………

…………

7. Discuss the various ways in which seeds and fruits are adapted for

dispersal. (20mks)

8. Describe how the mammalian ear is adapted to perform its functions.

(20mks)

2010 Pyramid Projections.009 BIOLOGY PAPER 2

1. Below is a diagram of an organism found in water, Study it and answer the following questions

(a) State the kingdom in which the organism belongs.

(1mk)

(b) Name the parts labeled

B (1/2mk) Y (1/2mk) (c) State the functions of the following parts

44


A (1mk) X (1mk) (d)Explain briefly why the organism is described as eukaryotic (1mk) 2. The diagram below is a skull of a certain animal.

(a) Identify the structure labeled X

( 1mk)

(b) What is the main function of the structure labeled Z?

(1mk)

(c) (i) Suggest the diet for the animals whose skull is drawn above

(1mk)

(ii) Give two reasons for your answer in a(i) above

(2mks)

3. The diagram below shows a life cycle of a cockroach

(a) Name the hormone that would be at high concentration during. (i) First week

(1mk)

(ii) Second week

(1mk)

(b) Name the structure that produces hormone in a (ii) above

(c) Explain briefly how a cockroach is adopted to its habitat

(2mks)

4. The pedigree chart below illustrates the inheritance of haemophilia. The gene ‘h’ for haemophilic condition is recessive to ‘H’ for blood clotting.

45


(a) Suggest the possible genotypes of individuals (i) 7

(1mk) (ii) 9 (1mk)

Using a punnet square work out the possible Genotypes of offsprings if individual number 4 married a haemophilic male (2mks)

(b) Explain why there are no carrier males

(1mk)

5. An experiment was set up as shown in the diagrams below. All the four experimental set ups, W, X, Y and Z were placed in the sunlight.

(a) After 10 minutes the coloured liquid in W had risen to the top of

the scale. Explain this observation.

(2mks)

(b) What was the purpose of set up X in this experiment?

(1mk)

(c) Explain the results that would be expected in Y and Z after 1 hour. (2mks)

(i) Y (ii) Z

6. The diagram below represents a bone from a mammal.

46


(a) Identify the bone (1mk) (b) (i) Name the part labelled ‘X’ (1mk) (ii) State the biological significance of the part labelled X (1mk) (c) Draw an arrow against the diagram above showing the anterior end (1mk) (d) What is the importance of part labelled (1mk) 7. The figure below shows the body temperature of a person before,

during and after taking a cold bath. (The temperature of the bath water was 220C).

(a) For how long was the person in the bath? (1mk)

(b) Explain why the person’s body temperature decreased

(1mk)

( c) Explain the role played by the following in helping to return the body temperature to normal. (i) The liver

(1mk) (ii) The blood vessels in the skin (1mk) (iii) The body muscles

(1mk) 8. All insects are believed to have evolved from a common ancestor,

however presently, insects differ widely in a variety of ways; for example their mouth parts are adapted to different modes of feeding such as biting, piercing and sucking. (a) Name the type of evolution exhibited by the insects in above example (1mk) (b) Explain how the differences in mouth parts came about. (2mks) (c) Give two examples of this type of evolution. (d) What are vestigial structures?

SECTION B:

47


Answer Question 9 (compulsory) in the spaces provided and one other question from this section in the spaces provided after question 11. 9. In a savanna grassland ecosystem the following organisms were

identified; Grasses, squirrels, gazelles, lizards, insects larvae, wild dogs, snakes, hawks, vultures and lions. Energy flow in the ecosystem was also determined as follows.

(a) Define the term ecosystem (2mks) (b) Name the process through which (i) Producers convert sun’s energy into chemical energy. (1mk) (ii) Living organisms convert chemical energy into heat energy lost to the environment. (1mk) (c) Identify organisms X (1mk) (c) Determine the amount of energy represented by A and B. (ii) What is the total amount of energy present within the producers? (1mk) (iii) What percentage of energy in the producers is lost as heat before reaching the tertiary consumers? (1mk) (iv) If 75% of the energy in the tertiary consumers is lost as heat, calculate the amount of energy presented by C (1mk)

(e) Explain briefly why it is advisable to feed one bag of maize grains to man instead of using the same bag to fatten steers, then supply beef to the human population. (2mks)

(f) (a) Construct a food web that would be noticed in the above ecosystem. (5mks) (b) What would be the effect of the following in the ecosystem? (i) Removing all the dogs (2mks) (ii) Bush fire (2mks) 10. (a) What is the role of the Gibberellins in plant growth and

development. (5mks) (b) List down the characteristics features of the

meristematic cells in a plant. (5mks)

48


(c) Explain the effects of unidirectional light on growth, in a seedling.

(10mks)

11. Explain how the mammalian male reproductive system is adapted to its functions.(20mks)

2010 Pyramid Projections.012

SECTION A (40 Marks) Answer ALL question in the section in the spaces provided.

1. In an experiment to compare the basal metabolic rate of some animals,

the amount of oxygen consumed per unit body weight in a given period of time was determined.

The table below shows the results of the investigations. Animal Body (Kg) Cm3 oxygen consumed gm/hr

Buffalo Man Rabbit Rat Mouse

546 58 3

0.1 0.02

47 203 318 700 1510

a) Comment on the volume of oxygen consumed by the Buffalo and the

mouse. (2 mks) b) Account for the above comparison for; (i) The Buffalo

(2 mks) (ii) The mouse

(3 mks) c) Comment on the relationship between body weight and oxygen

consumed. (1 mk) 2. In an experiment a group of students set up four Petri dishes labeled A,

B C and D as shown below. Study them and answer the questions that follow.

a) What was the aim of the experiment.

(1 mk) b) (i) What observations were made after a few days in petri dish A, D 2MKS

(ii) Account for observations made in b(i) above (2 mks) c) State three roles of enzymes in seed germination

(3 mks) 3. Study the diagram below and answer the questions that follow

Soaked Bean seeds on wet cotton wool

Soaked Bean seeds on dry cotton wool

Dry bean seeds on dry cotton wool

Water logged bean seeds

49


a) Name the blood vessels labeled A, B, C b) In which of the vessels labeled A, B and C would you expect to find the highest concentration of; (i) Glucose (1 mk) (ii) Amino acids (1 mk) (iii) Urea (1 mk) c) During fasting, the level of blood glucose in vessel C may be higher than the level in vessel B. Explain. (2 mks)

4. The flow chart below represents the results of successive crosses starting with yellow – flowered plants and white flowered plants and which both plants are pure breeding.

Parental phenotypes: Yellow flowered X White flowered

First filial generation Second filial generation Yellow flowered : White flowered 3 : 1

a) What were parental geneotypes. Use letter Y to represent the gene for yellow colour and y for white colour. (2 mks) b) (i) What was the colour of the flowers in the first filial generation. (1 mk) (ii) Give a reason for your answer in b(i) above. (1 mk) c) If 880 plants had yellow flowers in the second filial generation, how many F2 plants had white flowers, show your working. (2 mks) d) Name two defects due to non-disfunction. In chromosomal mutations (2 mks)

5. a) State the functions of the following cell organelles (i) Centriole (ii) Lysosome (1 mk)

Selfed

Aorta

Heart

Inferior venacava

50


b) What is the meaning of the term resolving power as used in microscopy. (1 mk) c) Give two roles of Active transport in plants. (2 mks) d) Explain why human Red blood cells burst when placed in distilled water. (3 mks)

SECTION B (40 Marks) Answer question 6 (compulsory) in the spaces provided and, either 7 or 8

in the spaces provided after question 8. 6. In an experiment to investigate the effect of light intensity on the rate

of photosynthesis, a shoot of elodea (water weed ) was used. The shoot was immersed in 2% sodium hydrogen carbonate solution maintained at 150C inan apparatus which allowed for collection of a gas evolved from the shoot. The gas given off was collected for five minutes at each light intensity and its volume recorded as shown in the table below. Light intensity (arbitrary units) Gas evolved (cm3 per 5 mins)

1 2 4 7 12 18 26 37 46

0.45 0.70 0.95 1.40 1.75 1.82 1.90 1.90 1.90

a) Using the data given in the table, plot a suitable graph of gas evolved against light intensity (6 mks)

b) Account for the rate of gas evolved between; (i) 1 and 18 arbitrary units

(3 mks) (ii) 26 – 46 arbitrary units

(2 mks) c) Explain why a green leaf is normally tested for presence of starch

instead of glucose. (2 mks)

d) How is the dry mass of a leaf determined (3 mks) e) Describe how the chloroplast is adapted to its functions. (4 mks)

7. a) Differentiate between Homologous and Analogous structures.

(4 mks) b) Describe how natural selection brings about adaptation of a species

to its environment (18 mks)

8. Describe the role of hormones in the human menstrual cycle (20 mks)

51


2010 Pyramid Projections 013 BIOLOGY Paper 2


Answer ALL questions in this section 1. The diagram below represents part of a cockroach gaseous exchange system

a) Name the parts labeled M and N. (2 mks) b) State the functions of the structure labeled M. (1 mk) c) Describe the path taken by carbon (IV) oxide as it diffuses out of the body of a cockroach. (3 mks) d) Name the structures in mammalian breathing system that are represented by M and N. (2 mks) 2. a) State the role played by these hormones in female menstrual cycle. (i) Follicle Stimulating Hormone (FSH) (1 mk) (ii) Progesterone (2 mks) (iii) Luteinizing Hormone (LH) (1 mk) b) Name two structures in plants where male and female gametes are produced. (2 mks) c) The diagrams below shows a stage during cell division

52


(i) Name the stage of cell division (1 mk) (ii) Give a reason for your answer. (1 mk) 3. A bone obtained from a mammal is represented by the diagram below.

a) (i) Identify the region in a mammalian body where the bone could have been obtained.1 mk) (ii) State four ways in which this bone is adapted to its functions. (4 mks) b) Name three types of skeletons found in the members of the kingdom animalia. (3 mks) 4. In an experiment a variety of garden peas having a smooth seed coat was crossed with a variety with wrinkled seed coat. All the seeds obtained in F1 generation had smooth seed coat. The F1 generation was selfed. The total number in F2 generation was 7324. a) Work out the total number of wrinkled seeds in the F2 generation. (2 mks) b) Give an explanation to the absence of plants with smooth seed coat in the F1 generation. (1 mk) c) The following diagrams represent examples of chromosomal mutation.

Name the types of chromosomal mutations represented by X and Y.

(2 mks) d) Other than the above named types of chromosomal mutations, name three other types of chromosomal mutations. (3 mks) 5. In an experiment the table below shows the approximate distribution of blood groups in a sample of 100 people in a population.

Blood group Frequency Rhesus +ve Rhesus -ve A 26 22 4 B 20 18 2

AB 4 3 1 O 50 42 8

53


a) Calculate the percentage of rhesus negative (Rh – Ve ) individuals in

the population.(2 mks) b) Account for; (i) The large number of blood group O individuals in a population.

(2 mks) (ii) The small number of individuals with blood group AB (2 mks) c) The diagrams below represents a blood smear on a glass slide.

(i) State the importance of structure C being in large numbers.

(1 mk) (ii) Give a reason why structure C would be found in large numbers at high altitude than at low altitude. (1 mk) (iii) Name the process by which structure A would engulf structure B. (1 mk)

SECTION B (40 Marks) Answer question 6 (compulsory) and either question 7 or 8 in the spaces

provided after question 8. 6. The table below shows the population of a housefly Musca domestica

which is parasitized by wasps of species Nasonia spp. The investigation of their population growth pattern was carried out for 70 weeks. In these, experimental space and physical factors were assumed not to be limiting.

Time weeks 0 5 10 15 20 25 30 35 40 45 50 55 60 65Musca domestica 40 70 110 260 350 480 400 395 350 40 60 140 250 240Nasonia spp 10 20 30 45 100 200 300 380 410 250 60 20 40 200

a) Using the readings in the table, plot graph on the same axis of population growth of organisms against time. (8 mks) b) Account for the growth of; (i) Musca domestica between 10th week – 25th week. (1 mk)

(ii) Nasonia species between 40th week – 50th week. (1 mk) c) What is the population of;

(i) Nasonia spp on the 62nd week. (1 mk)

54


(ii) Musca domestica on the 4th week. (1 mk) d) Bemex, another parasite of housefly was introduced into the ecosystem. Giving a reason what will be the effect on the population of;

(i) Housefly Musca domestica (2 mks) (ii) Nasonia spp (2 mks)

e) In estimating the population of Musca domestica in the experiment above, capture – recapture method was used. Describe the procedure which was followed. (4 mks) 7. a) Describe how insect pollinated flowers are adapted to pollination. (14 mks) b) Explain how a seed is formed in a flowering plant. (6 mks) 8. Discuss the various evidences which show that organic evolution has taken place. (20 mks) Name ………………………..…………………………

Index No. ..……………………………….….

School ………………………………………………...

231/2 BIOLOGY Paper 2 (Theory) Time: 2 Hours 2010 Pyramid Projections.014 Kenya Certificate of Secondary Education (K.C.S.E) 231/2 BIOLOGY Paper 2 (Theory) Time: 2 Hours INSTRUCTIONS TO CANDIDATES

• This paper has Two Sections A & B. • Answer ALL the questions in section A in the spaces provided on the

question paper. • In Section B answer question 6 (compulsory) and either question 7 or 8

in the spaces provided after question 8. FOR EXAMINER’S USE ONLY.

SECTION QUESTIONS MAXIMUM

SCORE

CANDIADTES

SCORE

A 1 8

55


2

3

4

5

8

8

8

8

B 6

7

8

20

20

20

TOTAL SCORE

This paper consists of 9 printed pages. Candidates should check the question paper to ensure that all the

Pages are printed as indicated and no questions are missing. 1. An organism was exposed to different temperatures but the body

temperature remained constant at 36.70C.

a) What type of an organism is it in terms of thermoregulation?

(1 mk)

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b) Describe one advantage of this condition to the organism.

(1 mk)

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c) List two ways by which the body of human being loses heat.

(2 mks)

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d) What changes occur in the skin at a room temperature of 400C.

(3 mks)

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e) Explain why it is important to reduce heat production in the body

from 400C to 370C(1 mk)

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2. The diagram below represents the structure of a gill from a bony fish.

a) Name the parts labeled A and B.

(2 mks)

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b) State the function of the part labeled C.

(1 mk)

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A

C

B

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c) Describe the importance of the counter flow system in the structure

labelled A. (2 mks)

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d) Describe the mechanism of gaseous exchange in protozoa.

(3 mks)

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3. The graph below shows the relationship between the numbers of

herbivorous and carnivorous in a park.

a) (i) Identify the curve representing herbivores

Time

No.

of i

ndiv

idua

ls

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(ii) Give reasons for your answer.

(2 mks)

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b) Suggest two reasons for the slope of graph X between points A and

B. (2 mks)

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c) (i) Name the relationship between the two types of organisms as

portrayed by the graph.

(1 mk)

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(ii) State the significance of the relationship stated in (i).

(1 mk)

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d) Describe the longterm effect on the parks ecosystem if the species of

the canivores were to become extinct.

(2 mks)

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4. In a family with four children, three were found to have normal skin

pigmentation while one was an albino. Using A to represent gene for normal

skin pigmentation and a to represent the gene for albinism,

a) What are the genotypes of the parents?

(2 mks)

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b) Work out the genotypes of;

(i) Normal pigmented children

(ii) The albino child

(2 mks)

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Genotype of normal pigmented children.

(2 mks)

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Genotype of the albino child.

(1 mk)

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c) What is the probability that the fifth child will be an albino?

(1 mk)

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5. a) State the effect of each of the following hormones on the human

uterus.

(i) Oestrogen

(1 mk)

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(ii) Progesteron

(1 mk)

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b) Name the blood vessel in the umbilical cord that;

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(i) Carries blood away from the foetus.

(1 mk)

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(ii) Carries blood to the foetus.

(1 mk)

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c) Name the materials that are transported in each of the blood vessels

you have named in b) (i) and (ii)

(2 mks)

(i)

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(ii)

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d) One type of contraceptive pills contains both oestrogen and

progesterone. Explain briefly how such a pill prevents conception.

(2 mks)

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Answer question 6 (compulsory) in the spaces provided and either

question 7 or 8 in the spaces provided after question 8

6. The formation of acid rain is a serious environmental concern today.

Sulphuric acid is present in acid rain and has adverse effects on both plants

and animals.

a) Name two other acids (other than sulphuric acid) that can be found

in acid rain. (2 mks)

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b) An experiment was carried out to investigate the effects of dilute

sulphuric acid on the growth of plant seedlings.

Batches of seedlings were grown in glass dishes on filter paper to

which dilute sulphuric acid was added. The dishes were then incubated.

The root and shoot lengths were measured after 65 hours. The results

obtained are shown in the table below.

Sulphuric acid concentration

(mol/dm-3)

Mean root length

(mm)

Mean shoot length

(mm)

0

1 x 10-3

3 x 10-3

4 x 10-3

6 x 10-3

7 x 10-3

8 x 10-3

9 x 10-3

10 x 10-3

55.5

63.4

6.5

2.0

1.8

1.5

1.3

1.3

1.0

25.2

18.4

9.5

4.6

0.8

0.5

0.3

0.0

0.0

63


Plot a graph of the mean root length and the mean shoot length against

the sulphuric acid concentration on the same grid.

(7 mks)

c) Describe the relationship between the concentration of sulphuric

acid and the:-

(i) Growth of shoots

(2 mks)

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(ii) Growth of the roots

(2 mks)

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d) Estimate the mean root and the mean shoot lengths when the

concentration of sulphuric acid is

5 x 10-3

(2 mks)

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e) State two other effects of acid rain.

(2 mks)

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f) State three ways of preventing acid rain.

(3 mks)

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7. Describe the process of digestion that takes place when one eats an egg

and ugali. (20 mks)

8. Discuss the various evidences which show that evolution has taken place. (20 mks)

65


.2010 Pyramid Projections – 015 BIOLOGY

Paper 2 SECTION A (40 Marks)

Answer ALL questions in this section in the spaces provided. 1. A certain student performed an experiment to investigate a certain

physiological process. She used potted plants which were previously destarched and immediately treated as shown in the diagrams below.

She covered plotted plant A with a transparent polythene bag together with a beaker containing sodium hydroxide solution labelled X. She covered potted plant B with a black polythene bag. Potted plant C was left not covered. Potted plant D was also not covered but instead the soil was injected with large amount of concentrated sodium chloride solution labelled Y. The plants were then exposed to strong sunlight for about six hours. a) State the physiological process she was investigating with the set up A, B and C. (1 mk) b) (i) After treating the plants as shown, what further test would have been necessary to make a conclusion on the effect of the treatment? (1 mk) (ii) What observations, for test on b) (i) above would be made on leaves from plant B and C. (2 mks) Plant B Plant C c) Account for the result got from plant A. (2 mks) d) Explain the response shown by plant D if the atmosphere became warm and dry as well. (2 mks)

2.. In an investigation to the digestion of gelatin by an enzyme trypsin, the end product is shown by the clearing of the film (becomes colourless) as shown in the diagram below.

TRYPSIN SOLUTION

EXPOSED FILM

SILVER SALTS

Beginning of experiment End of experiment

66


Seven test tubes, each with a different buffered pH solution and 1cm3 of 0.5% trypsin solution were placed in a water bath at 350C for 5 minutes. Small pieces of exposed film were simultaneously placed into each test tube and the time taken for the film to clear was recorded as shown in the table below.

pH Time taken for film to clear in minutes 6.0 6.5 7.0 8.0 9.0 9.5 10.0

30 20 13 5 8 20 35

a) (i) What is the optimum pH for trypsin? (1 mk)

(ii) Give a reason for your answer in a) (i) above. (1 mk) b) Suggest a suitable control required for this experiment. (1 mk) c) Give a reason for choosing the control in b) above. (1 mk) d) Explain the need for water baths in this experiment. (1 mk) e) Explain why it is necessary to place the seven test tubes in the water bath for 5 minutes before inserting the film into each. (1 mk) f) With a reason, predict what would have happened to the time to clear had the experiment been carried out at 650C. (2 mks) Prediction Reason

3. A group of students carried out an ecological study and counted the following organisms on a mango tree. Sap – sucking ants = 120 Herbivorous moths = 100 Carnivorous insects = 2 Insect eating bird = 1

a) From the study above, make a suitable food web. (2 mks) b) Using the data and a suitable scale, draw a pyramid of numbers for the ecosystem.(3 mks)

c) Identify (i) The producer (1 mk) (ii) Primary consumers in the ecosystem. (1 mk)

4. a) What is the importance of mitosis in living organisms? (1 mk)

b) The diagram below shows the female urinogenital system.

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(i) Name the parts labelled. E &F (2 mks) (ii) What is the role played by the parts labelled. A B C D G (5 mks)

5. a) Name one example of sex – linked gene in man associated with Y – chromosome.(1 mk)

b) Haemophilia is a sex – linked disorder in humans. It is caused by a recessive allele h’ present in X – chromosome. A normal man marries a carrier female. (i) What would be the genotypes of parents in this marriage? (2 mks) (ii) What would be the genotype of offsprings in the marriage above? Show your working. (3 mks) (iii) From the offspring’s in (ii) above, give the ratio of completely normal children to haemophiliac children. (1 mk) (iv) Why is it that in a given population, the percentage of haemophiliac males is higher that that of haemophiliac females. (1 mk)

SECTION B (40 Marks) Answer question 6 (compulsory) in the spaces provided and either

question 7 or 8 in the spaces provided after question 8. 6. An experiment was carried out to determine the growth of a variety of

bamboo and a variety of maize plants in two adjacent plots. The average height and average dry weight of plants from the two populations were determined over a period of twenty weeks. The data is as shown in the table below.

7. BAMBOO MALE

Age in weeks

Average in meters

Average dry weight in

grams

Average height in meters

Average dry weight in

grams 2 4 6 8 10 12 14 16 18 20

1.3 4.0 8.2 12.1 13.9 14.1 14.3 14.4 14.6 14.6

52 182 445 682 801 957 1025 1062 1127 1229

0.3 0.5 0.8 1.2 1.7 1.9 2.1 2.1 2.1 2.1

20 29 57 78 172 420 704 895 926 908

a) On the same axis, plot a graph to show the changes in average dry weights of the bamboo and maize plants against time. (6 mks) b) (i) Which of the two plants had a greater productivity by the end of the experiment. (1 mk) (ii) Give a reason for your answer in b) (i) above. (1 mk) c) Explain the following: (i) Between weeks 14 and 18, the average height of maize plants remained constant while the average dry weight increased. (2 mks) (ii) Dry weight was used instead of fresh weight in this experiment. (3 mks)

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(iii) Describe how the average height and average dry weight of the plants were determined in this experiment. d) Why was it appropriate to use both weight and height in this experiment? (1 mk) e) Give a reason why secondary thickening does not occur in bamboo and maize plants. (1 mk)

7. a) In Britain, it is observed that there are two varieties of a moth species (Briston betulania). These are the light coloured peppered moth and the melanic form (dark coloured). It is observed that the light coloured moth is at high population in the forest land while the melanic form was at high population near industries. Explain the evolution principle behind the above observation.

(16 mks)

b) State and explain the principles of Larmack’s theory of evolution. (4 mks)

8. a) Describe how small intestines is adapted for its functions. (12 mks)

b) Explain how digestion of various food substances takes place in the duodenum. (8 mks)

Name………………………………………………… Index No. ……………………. School ………………………………………………...

231/2 BIOLOGY PAPER 2 (THEORY) Time: 2 HOURS

2010 Pyramid Projections 016 Kenya Certificate of Secondary Education (K.C.S.E)

231/2 BIOLOGY PAPER 2 (THEORY) 2HRS


• Write your name, index number and the name of the school in the

space provided.

• This paper consists of 2 sections A, and B

• Answer ALL the questions in section A.

• In section B, answer question 6 (Compulsory) and either question 7 or

8 in the spaces provided after question 8.

69


FOR EXAMINERS USE ONLY

Section Questions Maximum Score Candidates Score

A

1 2 3 4 5

8 8 8 8 8

B 6 7 8

20 20 20

TOTAL SCORE 80

This paper consists of 10 printed pages. Candidates should check the question paper to ensure that all pages are printed as

indicated and no questions are missing


Answer ALL the questions in this section in the space provided

1. The diagram below is a part of a mammalian skeleton

a) Name the parts labeled A and B

(2 Marks)

A

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B

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b) State the function of the part labelled C

(1 Mark)

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70


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c) Name the type of joint formed at E

(1 Mark)

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d) Explain how cardiac muscles are adapted to their functions

(4 Marks)

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2. A student set up three thermos flasks X, Y, Z containing an equal

quantity of beans. Moist germinating beans were placed in flask X; boiled

beans were placed in Y and boiled beans soaked in antiseptic were placed

in flask Z. Thermometers were dipped into the beans and the flasks were

placed upside down by means of stands. The table below shows the

thermometer readings in 00 c.

71


1st

Day

2nd

Day

3rd

Day

4th

Day

5th

Day

6th

Day

7th

Day

FLASK

X

FLASK

Y

FLASK

Z

20

20

20

21

20

20

22

21

20.5

24

22.5

20

25

26

20.5

25

28

20

25

30

20

a) Suggest the aim of the experiment

(1 Mark)

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b) Explain why there is no significant heat production in Z after

day five (2 Marks)

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c) What is the significance of flask Z?

(1 Mark)

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d) Why were vacuum flasks used instead of glass flasks

(1 Mark)

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e) Name any two environmental factors that could cause seed

dormancy in seed in

flask X

(2 Marks)

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f) Name the processes that lead to increase in temperature in flask

X (1 Mark)

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3. Suppose you are asked to study the population of crabs in a pond.

a) List down the apparatus that you would need for its

investigation. (2 Marks)

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b) State the method of sampling used and give a reason for your

choice (2 Marks)

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c) What precautions should be taken when performing this

investigation (2 Marks)

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d) State two methods that you would use to determine what the

crab in the pond

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feed on.

(2 Marks)

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4. The diagram below shows the internal arrangement of muscles of this

iris of the eyes

Circular muscle fibres

Radical muscle fibres

a) How is the pupil affected by contraction of

i) Circular muscles

(1 Mark)

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Radial muscle fibres

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ii) Radial muscles

(1 Mark)

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b) Where are light sensitive cells located in the eye

(1 Mark)

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c) What is shortsightedness

(1 Mark)

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d) Explain why cones have a higher visual activity as compared to

rods (2 Marks)

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e) Which structure in the ear detects

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i) Sound waves

………………………………………………. (1 Mark)

ii) Change in posture

…………………………………………… (1 Mark)

5. a) Write down the base sequence of messenger RNA (mRNA) that

would be coded from

DNA strand shown below.

( 1 Mark)

C – A – T – G – A – G – T

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b) What is mutation

(1 Mark)

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c) Name two factors that may cause mutations

(2 Marks)

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d) Name two types of chromosomal mutations

(2 Marks)

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e) What is the significance of chiasma formation during meiotic

cell division (2 Marks)

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Answer question 6 (compulsory) in the spaces provided and either of the

questions 7 or 8 in the spaces provided after question 8

6. The amount of blood flow through various parts of mammalian body

was measured in cubic centimeters per minute at rest and also during

different physical activities.

The results are as shown in the table below.

Blood flow in cm3 / min

Part of body At rest During light

exercise

During strenuous

exercise

Heart muscle

Gut

Skeletal

muscle

Kidney

200

1300

1100

900

400

300

1000

5050

650

1300

1050

400

23000

250

600

78


Skin

a) Calculate the percentage change in the blood flow through the

skeletal muscle and gut when the animal was subject to

strenuous exercise from rest.

i) Skeletal muscle

(2 Marks)

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ii) Gut

(2 Marks)

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b) Account for the differences in the amount of blood flow

through the gut and skeletal muscle.

i) At rest

(4 Marks)

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ii) During strenuous exercise

(3 Marks)

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…………………………………………………………………………

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c) How does the heart increase blood flow to some parts of the

body during strenuous exercise

(2 Marks)

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d) Explain the results obtained from skin

i) at rest

(2 Marks)

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ii) during light exercise

(2 Marks

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e) Name three substances that are removed from the body by

kidneys (3 Marks)

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7. a) What is meant by natural selection

(3 Marks)

b) Explain how natural selection brings about adaptation of a

species to its

environment

(17 Marks)

82


8. a) Describe secondary thickening in flowering plants

(14 Marks)

b) Describe one method which can be used to measure the average

growth rate of a single leaf on a plant

(6 Marks)

2010 Pyramid Projections.017 BIOLOGY

Paper 2 THEORY

SECTION A (40 Marks) Answer all questions in this section in the spaces provided

1. The diagram below is an illustration of the human digestive system

a) Name the structures labeled A, B, C and D. (2 mks) b) State the function of Hydrochloric acid secreted by walls of B. (1 mk) c) Explain how structure D is adapted for its functions. (2 mks) d) When the duct of structure C is blocked, the regulation of blood sugar level remains normal while food digestion is impaired. Explain. (3 mks) 2. The diagram below illustrates a process in a given species of organisms.

a) (i) Name the organism. (1 mk) (ii) Identify the process shown to be taking place. (1 mk) (iii) State three economic importances of organisms found in the kingdom in which the organism shown above belong. (3 mks)

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b) (i) Define the term species. (1 mk) (ii) State two principles of Binomial nomenclature. (2 mks) 3. The diagram below shows some bones and the muscles in the human arm.

a) Name the bones labeled A, B and C. (3 mks) b) Name the type of joint found between bones A and B. (1 mk) c) Name and state the function of fluid X. (2 mks) d) Name the type of fibre X (1 mk) e) The pair of muscles labeled P and Q are “antagonistic

muscles”. Explain the meaning of this term. (1 mk)

4. a) When does the number of red blood cells and white blood cells increase in the body? (i) Red blood cells; (1 mk) (ii) White blood cells; (1 mk) b) Explain why it is NOT advisable to; (i) Light a jiko in a poorly ventilated room. (2 mks) (ii) Keep a potted plant in the bedroom. (1 mk) c) Explain why it is important to screen the blood tissue before transfusion is done (2 mks) d) Explain why a person with blood group O is said to be a universal donor. (1 mk) 5. a) The sequence below is a portion of a nucleic acid.

B — M — B — M — B | | | | | C G U C C

With a reason, identify the nucleic acid to which the portion belongs. (2 mks) b) In humans, the gene responsible for colour blindness is located on the X-chromosome. The figure below shows a pedigree of a certain family.

1 2

3 4 5 6

7 8

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Key Colour blind man Normal male Colour blind female Normal female (i) Indicate the genotypes of individuals 4, 5 and 7. (3 mks) (ii) What is the probability that individual number 10 would be heterozygous for the characteristic? (1 mk) c) Name two sex – linked traits in humans associated with theY-chromosome (2 mks) SECTION B (40 Marks)

Answer question 6 (compulsory) in the spaces provided and either question 7 or 8 in the spaces provided after question 8.

6. A 10gram sample of wheat grains was germinated on moist filter paper. Half of the sample was grown in normal daylight and the other half in permanent darkness. Samples from each group were weighed every 48hours. The fresh mass was found in each case and the following results were obtained. Day Fresh mass of seeds Fresh mass of seeds grown in light (g) grown in darkness (g) 0 10.0 10.0 2 13.9 13.8 4 16.0 16.6 6 20.0 21.2 8 26.6 26.6 10 34.7 32.2 12 43.8 31.6 14 53.6 28.0 16 61.4 25.0 18 68.2 20.6 a) On the same axes, plot graphs of the fresh mass against time. b) Account for the difference between the two graphs. (3 mks) c) What difference would it make to the results of the graph if the dry mass and not the fresh mass was obtained for the seedlings grown in the dark and in the light? Explain. (3 mks) d) What was the mass of the seedlings in light on the 17th day? (1 mk) e) State three external conditions necessary for germination to take ace.(3 mks) f) List down the three hormones that affect plant growth and development. (3 mks) 7. a) State the meaning of the following terms as used in biology; (i) Secretion (1 mk) (ii) Excretion (1 mk) (iii) Egestion (1 mk) b) Explain how the mammalian kidney is adapted to its functions. (17 mks) 8. Describe how xerophytes are adapted to living in arid conditions. (20 mks)

9 10 11

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NAME:…………………………………… INDEX NO:…….

2010 PYRAMID PROJECTIONS-018 231/2 BIOLOGY PAPER 2 (THEORY) 2 ½ HOURS INSTRUCTIONS TO CANDIDATES:

� This paper has two sections A and B printed on 16 pages � Answer all the questions in section A in the spaces provided

on the question paper. � From section B answer question 6 (compulsory) and either

question 7 or 8 in the spaces provided after question 8.

FOR OFFICIAL USE ONLY Section Questions Maximum score A

1 8 2 8 3 8 4 8 5 8

B

6 20 7 20 8 20

Total 1. In a certain habitat; i) Gazelles, termites, guinea fowls and grasshoppers feed on grass. ii) Guinea fowls also feed on grasshoppers and termites iii) Vultures feed on guinea fowls and leopards. iv) leopards feed on gazelles. a) Construct food web to show the above feeding relationships. (4mks)

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b) Name all organisms in trophic level two. (1mk) ……………………………………………………………………………… c) State the short term effects on the ecosystem, if lions invaded the area. (2mks)

………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………

d) What is the role of vulture in the habitat. (1mk)

……………………………………………………………………………………………………………………………………………………………………………

2

The diagram above represents an apparatus used to measure the rate of transpiration.

a) Name the apparatus above. (1mk)

……………………………………………………………………………… b) Give reasons why the following precautions are undertaken:- i) Cutting shoots under water. (1mk)

……………………………………………………………………………………………………………………………………………………………………………

ii) Keeping the system air tight. (1mk)

……………………………………………………………………………………………………………………………………………………………………………

c) What would happen to the air bubble if the set up was placed

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i) In a dark room. (1mk)

………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………

ii) In an air current created by a fan. (1mk)

………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………

iii) In the sun with leaves smeared with Vaseline on both sides. (1mk)

………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………

d) Give a reason for your answer in c(i) above. (2mks)

………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………

3. In a certain plant species which is normally green, a recessive gene for

colour (n) causes the plants to be white when present in a homozygous state. Such plants die at an early age. In the heterozygous state, the plants are pale green in colour but grow to maturity.

a) Suggest a reason for the early death of the plants with the homozygous recessive gene. (2mks) ……………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………

b) If a normal green plant was crossed with pale green plant what would

be the genotypes of the F1 generation? (Show your working) (4mks)

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c) If seeds from the heterozygous plants were planted and the resulting

plants allowed to self pollinate, work out the phenotypic ratio of the plants that would grow to maturity. (2mks)

4. The cells of a certain herbaceous plant were found to have an average

diameter of 2.5 micrometers. The cells were placed in different concentrations of sugar solutions and the results obtained were as shown in the table below. Concentration of sugar solution (%)

Diameter of cells (micrometer)

1 5.0 5 4.0 10 3.0 15 2.0

a) Use the table to determine concentration of cell sap. (2mks)

………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………

b) What term in given to the sugar solution whose concentration is equal

to that of the cell sap. (1mk) …………………………………………………………………………

…… c) Give an explanation for the average diameter of the cells placed in 1%

sugar solution compared to the normal diameter of the cells. (3mks) ………………………………………………………………………………………………………………………………………………………………………………………………………………………………

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………………………………………………………………………………………………………………………………………………………………………………………………………………………

d)i) State how the sap vacuole will appear after being placed in 15% sugar

solution. (1mk) ………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………

ii) Name the process responsible for that appearance of sap vacuole in d(i)

above. (1mk) …………………………………………………………………………

…… 5. The diagram below represents an eye defect.

a) Name the defect shown (1mk)

……………………………………………………………………………… b) What causes the defect.

(2mks)

………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………

c) With aid of a sketch diagram, show how the defect can be corrected.

(2mks)

d)

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The diagram above shows the results of an experiment that was set up in a dark room for some days. At the beginning of the experiment, the seedling had been placed in a horizontal position.

i) Name the type of response shown, (1mk) ………………………………………………………………………………………………………………………………………………………………………………

ii) Explain the results obtained at point B.

(2mks) ………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………

SECTION B (40MKS) Answer question 6 (compulsory) and either question 7 or 8 in the spaces provided after question 8. 6. The table below shows the concentration of lactic acid in mg/100cc of

human blood during and after exercise. Time(seconds) 0 5 10 15 20 25 30 35 40 45 50 55 Lactic acid mg/cc 22 25 45 90 86 85 84 60 44 25 22 22

a) Using the data provided in the table, plot a graph (6mks) b) Use the graph to determine the duration of vigorous exercise. (1mk) Suggest the normal concentration of lactic acid in the blood when the

person was resting. (1mk) ………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………

ii) What is the effect of lactic acid on the body muscles when its

concentration rises above 90mg/cc of blood (1mk)

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………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………

iii) Give three ways in which the body adjusts to the high concentration of

lactic acid. (3mks)

………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………

d) From the graph suggest the time when oxygen debt i) Occurred

(1mk) ………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………

ii) Began to be paid in the person’s body

(1mk) ………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………

e) List four differences between aerobic and anaerobic respiration in

animals. (4mks) ………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………

f)i State an organ that is not affected by high concentration of lactic acid.

(1mk) …………………………………………………………………………

…… ii) State a reason for your answer in f(i) above. (1mk)

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7. A student fed on a meal of ugali and lean meat. Describe its digestion. (20mks) 8a). Describe the theory of natural selection by Darwin (15mks) b) Explain how resistance to insecticides support the theory of natural

selection. (5mks)

NAME……………………………………………… .INDEX NUMBER……………………………………….. 2010 PYRAMID PROJECTIONS-019 231/2 BIOLOGY PAPER 2 TIME 2 HOURS INSTRUCTIONS

� Answer all Questions in Section A � Question 6 in section B is compulsory. Then choose either Question 7 or

Question 8. � All answers should be written in the spaces provided.

SECTION A ANSWER ALL QUESTIONS IN THE SPACES PROVIDED.

1. Sickle cell anaemia is an inheritable condition where an individual’s red blood cells are sickle shaped. A less serious condition is the sickle-cell trait where less than half the number of red blood cells are sickle-shaped and the rest are of normal shape.

a) Name one advantage of individuals who are sickle-cell trait. (1mks)

b) (i) Normal haemoglobin is abbreviated with HbA while sickle cell is Hbs.

Carry out genetic cross between a man who is a sickle-cell trait and a woman who has normal Haemoglobin (red blood cells) and who describe the phenotypes of the offspring’s. (3mks)

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(ii) One of the sons in (i) above married a sickle cell trait and gave rise to a daughter who is sickle cell anaemia. What was the genotype of the son. (1mk) (iii) What is the probability that their second born will be with normal haemoglobin. (2mks) (iv) What is the probability that their third child will be a sickle cell trait? (1mks)

2. Potted maize seedlings were grown in a room which was illuminated with sunlight from one direction as shown in the diagram below. The seedlings were divided into three groups.

Group A - coleoptiles were covered with black polythene. Group B - coleoptiles were cut off. Group C - was left Intact/Nothing was done to it.

a) With the aid of a diagram, show how each group of seedlings will look like after one week. (3mks)

b) Explain how the changes in (a) above came about. (3mks)

A B

C Light

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c) What response is being tested in the Experiment? (1mks)

d) What is the significance of this response to the plants? (1mks)

3. A student set up three thermos flask X,Y,Z containing an equal quantity of beans. Moist germinating beans were placed in flask X, Boiled beans were placed in Y and boiled bean seed soakedsoaried in Antiseptic were placed in flask Z. Thermometers were dipped into the beans and the flasks were placed upside down by means of stands. The table below shows the thermometers readings in 0C.

1st Day 2nd Day 3rd Day 4th Day 5th Day 6th Day 7th Day Flask X 20 21 22 24 25 25 25 Flask Y 20 20 21 22.5 26 28 30 Flask 2 20 20 20.5 20 20.5 20 20

a) Suggest the aim of the experiment. (1mks)

b) Explain why there is no significant heat production in X after day five. (2mks)

c) What is the significance of flask Z2. (1mks)

d) Why were vacuum flasks used instead of glass flasks? (1mks)

e) Name two environment factors that could cause seed dormancy in seed in flask X. (2mks)

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f) Name the processes that lead to increase in temperature in flask X. (1mks)

4. (a) State the reason why pepsin is produced in its in-active form pepsinogen in the walls of the stomach. (2mks) (b) Why is the enzyme salivary Amylose unable to exert its effect in the stomach.(1mk) (c) Explain why soluble milk caseinogens is converted into insoluble casein. (2mks) (d) State two functions of mucus produced along the alimentary canal. (2mk) (e) State the role of diastema in the herbivores. (1mks) 5. The table below shows the estimated number of organisms in a dam with the

exeception of the number of small fish.

Organisms Number Mosquito larvae Crocodiles Small fish Microscopic algae Large fish

8,900 100 12,000 950

a) Construct a possible food chain for the dam.

(2mks)

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b) Giving a reason, suggest the number of small fish in the dam.(1mks)

c) (i) Suggest a suitable method you can use to estimate the number of fish in a fish pond. (1mks)

(ii) Describe how you would carry out the method in(c) (i) above to estimate the number of fish in the pond. (4mks)

SECTION B Answer Question 6(Compulsory) and either Question 7 or Question 8 . In the space provided after question 8.

6. During germination and growth of a cereal, the dry weight of endosperm, the embryo and the total dry weight were determined at two day Intervals. The results are shown in the table below.

Time after planting days

Dry weight of endosperm(mg)

Dry weight of embryo(mg)

Total dry weight

0 2 4 6 8 10

43 40 33 20 10 6

2 2 7 17 25 33

45 42 40 37 35 39

a) Using the same axes, draw graphs of dry weight of endosperm,

embryo and the total dry weight against time. (7mk)

b) What was the total dry weight on day 5? (1mk) c) Account for

i) Decrease in dry weight of endosperm from day 0 to 10.(2mks)

ii) Increase in dry weight of embryo from day 0 to 10. (2mks)

iii) Decrease in total weight from day 0 to 8. (1mks)

iv) Increase in total dry weight after day 8. (1mks)

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d) State two factors within the seed and two outside the seed that cause

dormancy. i) Within the seed (2mks)

ii) Outside the seed (2mk)

e) Give two characteristics of meristematic cells (2mks)

7. a) State the functions of the following parts of the human ear.

i) pinna (1mks)

ii) ear ossicles (2mks)

iii) Auditory nerve (1mks) iv)

b) Describe fully how the human ear perceives sound. (16mks)

8. Describe the structure and functions of various parts of the Mammalian skin. (20mk)

…

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2010PYRAMID PROJECTIONS -023

BIOLOGY PAPER 2

(TIME: 2HRS

Instruction to candidate

This paper has three sections A, and B Answer all questions in sections A in the spaces provided on the question paper From section B, answer question 6 (compulsory) in the spaces provided and either questions 7 or 8in the foolscaps

SECTION A (40marks) 1. (a) What is meant by the term sex linked gene?

(2mks) (b) Red/green color blindness is controlled by sex linked genes.If a carrier mother is married to a man with normal colored vision (i) What would be possible genotypes of their offspring's. Use the symbol R to represent normal vision and R for color blindness

(2mks) (ii)What is the probability of the couple having color blind son?

(lmk) (c) State the type of gene mutations represented by the following analogue and explain (i) Intended message BRING THERMOS ON OUTING Actual message- BRING MOTHERS ON OUTING Type of mutation (lmk) Explanation

(1\2mk)

(ii) Intended message PLEASE SAY WHERE YOU ARE PLEASE STAY WHERE YOU ARE Type of mutation {1mk

Explanation {1\2mk}

2.The diagram below shows an experimental set up to investigate a certain scientific concept. The potted plant was first kept in the dark for 48 hrs and then exposed to sunlight for 2 hrs

(a)Why was the potted plant kept in the dark for 48 hrs?

(lmk)

(b)what scientific concept was stigated in the set-up experiment? (lmk)

(c)What is the purpose of sodium hydroxide pellets in the set up. (lmk)

(d) Leaves A and B were tested for starch (i)What is the purpose of testing leaf B for starch

(lmk)

Leaf B

Leaf A

Sodium Hydroxide

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Name the labeled C, D and E on tube diagram (3mks)

(ii)State the reasons why the following steps ai followed while testing the leaf for starch (I)Boiling the leaf in water for 5 minutes

(lmk (II)Boiling the leaf in absolute ethanol in a hoi water bath

(lmk)

(e)(i)What is meant by the term compensation point? (lmk)

(ii)Explain temperature as a limiting factor foi photosynthesis (lmk)

3.The figure below is a diagram of a vertical section of a mammalian tooth C .......................................... D .......................................... E ............................................

b)How are the structure labeled C adapted to their functions? (lmks)

c) Suggest giving reasons what type of tooth it is? (2mks)

d)Why is eating a lot of sugar food harmful to the teeth? (lmk)

e) State one way of preventing tooth decay. (lmk)

4. The diagram below shows a food web in a fresh water ecosystems. Study it to answer the questions that follow a) Construct two food chains with quaternary consumers

(2mks)

b)Explain why it is rare to find food chains ending with quaternary consumers (lmk)

c)(i)What is the main source of energy in the above Ecosystem? (lmk)

(ii) Explain how the energy from the source you have named in C (i) is made available to large fish in the lake(lmk)

d)Explain why the primary productivity of aquatic ecosystems decreases with depth

(lmk)

e) State any four ways in which human activities would interfere with the ecological balance of the above lake ecosystem.

(2mks)

5. The figure below is a diagram of a potometer. Shoot

What is the purpose of the setup? (lmk)

S- Reservoir

shoot

Air Bubble

Nerve endings

C

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b)State the precaution which should be taken when cutting the shoot used in the set-up experiment? {lmks) c)The rate of transpiration was determined under normal laboratory conditions. Giving reasons explain the differences you would expect if the measurements were repeated under the following conditions. (i)The shoot was placed close to a heat source

(lmk) (ii)The set up was enclosed in a polythene bag

(lmk) (iii)The shoot is placed in current of air created by a fan.

(2mks) (iv)The leaves are removed SECTION B (40mks) Answer question 6 (compulsory) in the provided spaces and either question 7 or 8

6. An experiment was carried out to investigate the effect of hormones on growth of lateral buds of three pea plants .The shoots were treated as follows Shoot A - Apical bud was removed Shoot B - Apical bud was removed and gibberrellic acid placed on the cut shoot Shoot C - apical bud was left intact The lengths of branches developing from the lateral buds were determined at regular intervals. The results obtained were as shown in the table below

Time in days

Length of branches in millimeters

Shoot A Shoot B Shoot C

0 3 3 3 2 10 12 3 4 28 48 8 6 50 90 14 8 80 120 20 10 118 152 26 a)Draw graphs to show the lengths of branches against time

(8mks) j b)(i)What is the length of the branch in shoot B on the 9th day?

(lmk) (ii)What would be the expected length of the branch developing from shoot A on 11th day?

(lmk) c)Account for the results obtained in the experiment

Shoot A 2mks

Shoot B 2mks Shoot C 2mks d)Why was shoot C included in the experiment?(lmks)

e) State any three effects of auxins e.g. idol acetic on growth and development in plants

(3mks)

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7.a) State any three differences between monosaccharide's and polysaccharides

(3mks) b) Explain the biological functions of lipids to living organisms

(8mks) c)Describe the laboratory chemical test for proteins using Biuret's test

(2mks) d) Describe the role of following in mammalian digestive system

(i)Pepsin {2mks}

{ii} Bile {2mks}

{iii} Hydrochloric acid {2mks}

8.a)Distinguish between breathing and gaseous exchange and respiration (3mks)

b)Explain the factors that influences breathing in humans (8mks) c)Describe how the red blood cells are structurally adapted to their functions {9mks}

2010 © Pyramid Projections 231/2

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Biology Paper 2 16 Sample Ques t