Kenya Certificate Of Secondary Education (KCSE 2009) Biology Paper 2

SECTION A (40 marks)

Answer all the questions in this section in the spaces provided.

1. When the offspring of purple and white flowered pea plant were crossed, they produced purple and white flowered plants in the ratio of 3:1.
   Using letter H to represent the gene for purple colour:
   1. State the genotype of:
      1. Parents (2 marks)
      2. F₁ generation (1 mark)
         
         
   2. Workout for the cross between plants in the F₁  generation. (4 marks)
   3. Account for the colour of the flowers in plants of the F₁ generation. (1 mark)
      
      
2. The diagram below represents the lower jaw of a mammal.
   
   
   
   
   1. Name the mode of nutrition of the mammal whose jaw is formed. (1 mark)
   2. State one functional and structural difference between the teeth labeled J and L.
      Structural (1 mark)
      Functional  (1 mark)
      
      
   3. 1. Name the toothles gap labelled K.
      2. State the function of the gap named in (c)(i) above. (1 mark)
         
         
   4. Name the substance that is responsible for hardening of teeth. (1 mark)
      
      
3. 1. 1. What is meant by the term biological control. (1 mark)
      2. Give an example of biological control. (1 mark)
         
         
   2. 1. What is meant by the term eutrophication? (3 marks)
      2. What are the effects of eutrophication? (3 marks)
   3. Name a substance that is responsible for acid rain. (1 mark)
      
      
4. 1. 1. Name the changes that take place in the pupil and the iris of a human eye when a person moves from a dark room to a room with bright light. (3 marks)
      2. What is the significance of the changes explained in (a)(i) above. (1 mark)
   2. How does the human eye obtain nutrients? (3 marks)
   3. Explain why images that form on the blind spot are not perceived. (2 marks)
      
      
5. 1. Explain what happens when a wilting young plant is well watered. (3 marks)
   2. Name the support tissue in plants thickened with:
      1. Cellulose (1 mark)
      2. Lignin (1 mark)
   3. Give three functions of pectoral and pelvic fins in a fish. (3 marks)
      
      SECTION B (40 marks)
      Answer question 6 (compulsory) and either question 7 or 8 in the spaces provided after question 8.
      
      
6. An experiment was carried out to investigate effect of temperature on the rate of reaction catalyzed by an enzyme. The results are shown in the table below.
   
   
   
   
   1. On the grid provided, draw a graph of the rate of reaction against temperature. (6 marks)
      
      
      
      
   2. When was the rate of reaction 2.6 mg of product per unit time? (2 marks)
   3. Account for the shape of the graph between:
      1. 5^oC and 40^oC (2 marks)
      2. 45^oC and 60^oC (3 marks)
         
         
   4. Other than temperature name two other ways in which the rate of reaction between 5^oC and 40^oC could be increased. (2 marks)
   5. 1. Name one digestive enzyme in the human body which works best in acidic condition. (1 mark)
      2. How is the acidic condition for the enzyme named in (e) (i) above attained. (2 marks)
         
         
   6. The acidic conditions in (e) (ii) above is later neutralized.
      1. Where does neutralization take place? (1 mark)
      2. Name the substance responsible for neutralization. (1 mark)
         
         
7. How are flowers adapted to wind and insect pollination? (20 marks)
   
   
8. Describe the role of the liver in homeostasis in the human body. (20 marks)