KCSE Past Papers 2021 Biology Paper 3 (231/3)

KCSE Past Papers 2021 Biology Paper 3



1.a. You are provided with plant specimens labelled E, F, G, H, and J. Use the specimens to develop a dichotomous key that can be used to identify the plants from which they were

obtained based on the following characteristics in the order they are given: (6 marks)

i. Leaf form

ii. Leaf venation

iii. Leaf colour

b. Account for the likely observation if fresh specimen E was exposed to light and tested for starch. (3 marks)

c. Explain one observable feature that adapts plants from which specimen G and H were obtained to a dry environment. (2 marks)

d. Besides leaf characteristics, state one other observable characteristic on the plant from which specimen F was obtained that enables it to be placed in its Class. (1 mark)

2. You are provided with solution M which is a food substance.


a. Using the reagents provided, test for the food substance present in substance M and complete the table below. (12 marks)


Food Test Procedure Observation Conclusion

b. State two precautions one should observe while conducting the experiment in 2(a) (2 marks)

3. You are provided with specimen N and P which are plants of the same species grown under different conditions.

a. State two observable differences between the two specimens. (2 marks)

b.i. Name the phenomenon observed in specimen N. (1 mark)

ii. Explain how the knowledge on the phenomenon named in bi) is applied in agriculture(2 marks)

c. Account for the appearance of specimen N. (3 marks)

d. State two other environmental factors necessary for seed germination apart from light. (2 marks)

e. State two observable features on the specimens that make them be placed in the same Class. (2 mark)

(Visited 290 times, 1 visits today)
Share this:

Written by