Cameroon gce Biology 2017 A level paper 2

 

1. (a)       Define the term alternation of generations.
(b)    Draw an annotated life cycle of a moss to illustrate alternation of generations.
(c)    Why is water necessary for the life cycle of the moss?
( 6, 10, 4 marks)
(Total = 20 marks)
2. (a) State the characteristics of a respiratory surfaCe.
(b) Describe the mechanism involved in the ventilation of
(i)                 an insect and
(ii)               man.
(c) How is ventilation controlled in man?
(4, 4, 6, 6 marks)
(Total = 20 marks)
3. A gardener working on pepper plants got the following results:
  • When a pepper plant with long and yellow seeds was crossed with one with round and red seeds all the offspring hand long yellow seeds in the Fl.
  • A majority of the F1, pepper plants when crossed with a double recessive for both traits gave an equal
  • number of pepper plants with long yellow and round red seeds in the F2

C:       A few pepper plants from among the Fl when crossed with a double recessive gave in the F2, the
following phenotypic numbers

  • 890 long yellow seeds 900 round red seeds 104 long red seeds 110 round yellow seeds..
  • State the dominant and recessive traits in these crosses
  • What,can you suggest is responsible for the different phenotypic numbers of B and C?
  • Using appropriate symbols show the crosses of the findings in A, B and Your crosses should show all
    the necessary steps.

(2, 3, 15 marks) (Total = 20 marks)

 

 

 

  1. Describe how: .
  • A stomach of a ruminant herbivore is adapted to carry.out.its functions.
  • The nervous and hormonal systems control digestive secretions in the human gut.
  • , Auto digestion is prevented in the human gut.

(6, 10, 4 marks) (Total = 20 marks)

 

 

 

 

  1. (a) Define tropic and nastic responses stating one example in each case.

(ii)        List the differences between tropic and nastic responses.     •

(b)      Explain why phytochromes are involved in detecting photoperiods in flowering plants?

(e)       List 5 uses of auxins in agriculture.

(10, 5, 5 marks) (Total = 20 marks)

 

 

 

 

 

 

 

  1. (a) Define a food web. Use organisms in a named ecosystem to illustrate the principle of a food web.

(b)         Briefly explain the following:

  • Ozone layer depletion;
  • Global warming and –
  • Eutrophication
  • (8, 12 marks)

(Total = 20 marks)

 

 

 

 

  1. (a) What is:
  • Growth and
  • Cell differentiation?

(b)                 Discuss five factors: three external and two internal that affect growth in plants.

(5, 15 marks)

(Total = 20 marks)

 

 

 

  1. (a) Describe Biotechnology.

List the steps involved in a Biotechnological process.

(c)           .Describe each of the following:

  • Cheese production;
  • Yogurt production and
  • Production of the antibiotic penicillin

(3, 5, 12 marks) (Total =20 marks)

 

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