Biology 9700 · AS & A Level · Homeostasis in mammals

Homeostasis in mammals — practice question

In mammals, the kidney carries out: • the removal of urea by excretion • osmoregulation (the homeostatic regulation of the blood’s water potential).
(a(i))[2]

Outline how urea is produced in the body and where this happens.

(a(ii))[3]

The homeostatic regulation of blood water potential involves receptors, effectors and target cells. Identify the names and positions of these parts of homeostatic control in osmoregulation.

(b)[3]

The glomerulus and Bowman's capsule of the nephron play a key part in urine formation. Outline the role of the glomerulus and Bowman's capsule in the formation of urine.

(c)[3]

A concentrated urine has a high solute concentration and only a small volume of water. Mammal species differ in how well they can produce urine with a high solute concentration. Table 6.1 compares the ratio of the solute concentration of urine (U) to the solute concentration of blood plasma (P) in some mammal species. The habitats of the mammal species are also shown. Using Table 6.1, suggest what the different values of U:P indicate about how well these mammal species can withstand a shortage of water in their environment.

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