Biology 9700 · AS & A Level · Homeostasis in mammals

Homeostasis in mammals — practice question

The enzyme alanine transaminase (ALT) is located in the liver. It catalyses the conversion of the amino acid $alanine$ and $\text{-ketoglutarate}$ to the amino acid glutamate.
(a)[1]

Suggest why the liver may need to change one amino acid into another.

(b)[2]

Tumours may develop in the liver. Explain how a liver tumour develops.

(c)[1]

ALT can leak into the blood from liver tumour cells. An increase in the concentration of ALT in the blood causes a decrease in the water potential of the blood. State precisely the name and location of the cells where a change in the water potential of the blood would be detected.

(d)[5]

Describe the homeostatic function of ADH when the water potential of the blood decreases.

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This 9-mark question has a full step-by-step worked solution and mark scheme. One marking point: “Lack of glutamate or of an amino acid in the diet” …

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