KCSE Past Papers 2020 Biology Paper 3 (231/3)

2020 Biology Paper 3

Answer all the questions in the spaces provided.

1. You are provided with a piece of specimen N and the following reagents:

– Dilute hydrochloric acid

– Dilute sodium hydroxide

– Dilute hydrogen peroxide

– Water

You have also been provided with the following apparatus:

– Three test tubes

– 10ml measuring cylinder

– Scalpel


(i) Label the test tubes 1, 2 and 3.

(ii) Macerate (chop into tiny pieces) half of specimen N.

(iii) Place equal amounts of the macerated specimen into test tubes 1 and 2.

(iv) Cut the remaining half of the specimen into two equal pieces.

(v) Place one piece into test tube 3 and reserve the remaining piece.

(vi) Add about 2cm3 of dilute hydrochloric acid into test tube 1, add about 2 cm3 ofsodium hydroxide into each of test tubes 2 and 3.(vii) Add about 5 cm3 of hydrogen peroxide into each of the three test tubes, 1, 2 and 3.

(a) Observe the amount of effervescence in each test tube and complete the table below.


Test tube Contents Amount of effervese nce observed Explanation

(10 marks)

(b) Use the reagents provided to test for the food substance present in the piece of specimen N reserved from (a). Observe and record in the table below


Procedure Observation Conclusion

(3 marks)

2. You are provided with photographs E, F, K and H, together with specimens G, J, L and M.

Using observable features in the photographs and specimens provided:

(a) Place with a reason, each of the following organisms in their respective Kingdom, Division or Phylum.

i) G(2 marks)

Division _______________________________

Reason ________________________________

(ii) E (2 marks)

Kingdom _______________________________

Reason ________________________________

(iii) M (2 marks)

Division ________________________________

Reason _________________________________

(iv) H (2 marks)

Phylum ____________________________

Reason _____________________________

(b) State two features in the following organisms that make them to be placed in different Classes:

(i) F and K (2 marks)

(ii) J and M (2 marks)

(c) Make a labelled diagram of specimen L. (1 mark)

(c) Explain the difference in the mode of reproduction exhibited by E and J.(1 mark)

3. You are provided with a specimen labelled P on a tile.

(a)(i) Name the Class to which the specimen belongs.(1 mark)

(ii) Give three reasons for your answer in (a)0) above.(3 marks)

(b) State three ways by which the organism is adapted to movement in its habitat.(3 marks)

(c) State two functions of the part labelled Q.(2 marks)

(d) Carefully lift the part labelled Q and observe the underlying structure.

(i) State the main function of the underlying structure observed.(1 mark)

(ii) State three ways by which the structure is adapted to its function.(3 marks)

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