Biology Paper 2,Nov/Dec 2012  
Questions:   1 2 3 4 5 6 7 8   Main
General Comments

Question 2


  1.   (i)   Outline the components of a reflex arc and state one function each of

         each component                                                                            [ 10 marks ]

(ii)     State four differences between a reflex action and a voluntary action[4 marks ]

  1.    Explain how insulin regulates the amount of glucose in the blood.       [ 6 marks ]



 This question was quite popular among the candidates and they had high scores.  Most
    candidates showed a good knowledge of the components of a reflex arc and functions
    of the components.

     The difference between reflex actions and voluntary actions were correctly tallied but 
    candidates failed to mention that reflex action is controlled by the spinal cord and hind
    brain.  Some candidates could not state how blood glucose is regulated by

     The expected answers are:
 (b)      Regulation of Blood glucose by insulin.

          When the level of glucose in the blood rises; insulin is secreted from the pancreas/ Islets of Langerhans; insulin stimulates  liver/fat/muscles to metabolise glucose; stimulates muscles and liver to store glucose as glycogen;  promotes the buildup of fats and protein; inhibits their use as an energy source; leading to lowering  of the level of glucose in the blood;
         When the blood sugar level falls; pancreas releases glucagon; which stimulates the breakdown of stored nutrients/conversion of glycogen to glucose; causing the blood sugar level to normalise.



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