O-LevelBiologyCoordination & Response5090/11 · May/June 2012 · Q201 Mark

In a kidney machine, protein molecules are not lost from the blood. How is loss of protein prevented?

AMembranes prevent protein molecules diffusing out of the blood.

BProteins are actively transported back into the blood.

CProteins do not enter the kidney machine.

DThe dialysis fluid contains protein, so there is no diffusion gradient.

✓ Correct answer

A: Membranes prevent protein molecules diffusing out of the blood.

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Topic: Coordination & Response, O-Level Biology (syllabus 5090). Multiple choice, 1 mark.
Source: O-Level Biology, May/June 2012 Paper 1 Variant 1, question 20.

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