((a)       What are hormones?                                                                              [3 marks]
 (b)       In a tabular form, state four differences between nervous coordination and hormonal coordination in  humans.                                                     [4 marks]
                    (c)       State three effects each of:
             (i)         Over-secretion;
             (ii)        Under-secretion of thyroxin on  mammals.                           [6 marks]
                    (d)      Make a diagram 10 – 12 cm long of the  reflex arc and label fully.  [7 marks]