Biology 9700 · AS & A Level · Homeostasis in mammals

Homeostasis in mammals — practice question

People with sickle cell anaemia have red blood cells with a lower capacity for carrying oxygen.
(a)[5]

Explain how the gene mutation responsible for sickle cell anaemia is linked to the lower oxygen-carrying capacity of red blood cells.

(b(i))[1]

Predict how an increase in blood volume affects ADH secretion and state one kidney-function consequence of this change in ADH secretion.

(b(ii))[1]

Suggest how a rise in blood pressure within the pulmonary capillaries can make fluid enter the alveoli.

(c)[4]

With reference to Fig. 3.1, describe how kidney disease affects the risk of developing TACO. Suggest reasons for this pattern.

(d)[3]

Patients who are at high risk of developing TACO after a blood transfusion may be given a type of drug known as a loop diuretic. In normal urine production, $99\%$ of sodium ions in the glomerular filtrate are reabsorbed and $1\%$ are excreted. In the urine production of people who take loop diuretics, $80\%$ of sodium ions in the glomerular filtrate are reabsorbed and $20\%$ are excreted. Explain how loop diuretics change water reabsorption in the kidneys and suggest why this lowers the risk of developing TACO after a blood transfusion.

Worked solution & mark scheme

This 14-mark question has a full step-by-step worked solution and mark scheme. One marking point: Sickle cell anaemia is inherited as a homozygous recessive condition

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