Biology 9700 · AS & A Level · Passage of information from parents to offspring

Passage of information from parents to offspring — practice question

Diabetes insipidus (DI) is a disorder that causes extreme thirst and the passing of very large volumes of dilute urine. One major cause of DI is a lack of ADH. ADH normally attaches to receptor proteins on the cell surface membranes of cells in the collecting ducts of nephrons.

(a)[3]

Outline how ADH affects the collecting ducts.

(b(i))[1]

Explain what the term sex linkage means.

(b(ii))[4]

Use a genetic diagram to demonstrate how parents who are unaffected by this condition can have a child with the inherited form of DI. Your response should include: symbols, parental genotypes, gametes, offspring genotypes, offspring phenotypes.

Worked solution & mark scheme

This 8-mark question has a full step-by-step worked solution and mark scheme. One marking point: “reference is made to enzyme/phosphorylase/signalling” …

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