A-LevelBiologyTransport in mammals9700/12 · May/June 2018 · Q311 Mark

If the left atrioventricular valve in the heart does not close completely it results in blood flowing back into the atrium during ventricular systole. What would be the immediate effect of this back flow?

Ablood flowing from the heart carries less oxygen because less blood enters the lungs

Bdiastolic pressure in the left ventricle falls because less blood enters the pulmonary artery

Clower systolic pressure in the left atrium and less blood enters the pulmonary artery

Draised pressure in the left atrium and less blood enters the aorta

✓ Correct answer

D: raised pressure in the left atrium and less blood enters the aorta

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Topic: Transport in mammals, A-Level Biology (syllabus 9700). Multiple choice, 1 mark.
Source: A-Level Biology, May/June 2018 Paper 1 Variant 2, question 31.

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