(a(i))[1]
State how the length of the loop of Henle is related to the water potential of the urine in the three mammals.
(a(ii))[2]
The nephron of a camel resembles that of mammal R. Suggest why it is important for the camel to produce urine with a very low water potential.
(b)[6]
Epithelial cells in the proximal convoluted tubule are specialised for selective reabsorption. Table 1.1 gives three features of these epithelial cells. For each feature, explain how it helps selective reabsorption.