EXCHANGE QUESTIONS
The diagram below shows a part of the gills of a bony fish  
   

 
a.   Identify the following features shown in the diagram  
  i) X  
      (1)
  ii) Y  
      (1)
  iii) Z  
      (1)
b.   Show on the diagram the direction of blood flow  
      (1)
c.   Give two adaptions that can be seen in the diagram that make the gill an effective gas exchange surface  
      (2)