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KCSE CLUSTER TESTS 25

Biology Paper 3

1.

You are provided with two sets of specimens, set A and set B obtained from the same plant. Observe the specimens carefully. i) Using a pestle and mortar crush a few of the specimens in set A. Add a little water, mix and decant to obtained an extract. Test the extract for the food substances it contains using the reagents given.

Record your results in the table below.

ii) Take a few of the specimens in set B and repeat the procedure in 1 i) above. Record the results in the table below.

iii) Explain the difference in results obtained in set A and set B above.

…………………………………………………………………………………………

iv) Name an enzyme responsible for the differences observed in the two sets.

…………………………………………………………………………………………

15 marks

2.

The diagram provided and labeled Q2 is an electromicrograph of a section through a leaf.

a) i) What is the likely habitat of the plant?

………………………………………………………………………………………………

ii) Give a reason for your answer in 2a) i) above

………………………………………………………………………………………………

b) Name the parts labeled J to M

J……………………………………………………………………………………………… K…………………………………………………………………………………………… L…………………………………………………………………………………………… M……………………………………………………………………………………………

c) State the role of the part labeled J and L

J………………………………………………………………………………………………

L……………………………………………………………………………………………

d) Calculate the diameter of the structure labeled L at its widest part given that the leaf was magnified X200. Give your answer in micrometres.

………………………………………………………………………………………………

………………………………………………………………………………………………

11 marks

3.

Figures 1, 2 and 3 provided and labeled Q3, are of the same organism but at different stages of their life cycle. Study the figures carefully.

a)

i) Using observable features only state the phylum of the organism in figure 4

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

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

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

…………………………………………………………………………………………

…………………………………………………………………………………………

iii) Give two differences between the organism in figure 3 and the organism in

figure 4

b) Figure 1,2, and 3 shows the same organism at different stages of incomplete metamorphosis.

i) What is the name given to the stage represented by figure 1

………………………………………………………………………………………

ii) Give the name of the hormone responsible for transforming organism in figure 1 into organism in figure 3

………………………………………………………………………………………

. iii) What is the importance of metamorphosis to the organism above.

………………………………………………………………………………………

………………………………………………………………………………………

iv) Label any three parts On figure 3

v) What is the economic importance of the organism in figure 4?

14 marks

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