(a)[2]
Define what is meant by excretion.
(b)[4]
The kidneys control the water potential of body fluids. This is called osmoregulation and it uses a negative feedback system. Outline the role of negative feedback in osmoregulation.
(c)[2]
Investigations have shown that if a person stays in a cold environment for more than $15$ minutes, urine production rises. This is called cold diuresis. Suggest how exposure to cold can lead to cold diuresis.