O-LevelBiologyCoordination & Response5090/12 · May/June 2020 · Q251 Mark

When a mother smokes during pregnancy, the oxygen supply to the fetus is reduced. Which row shows how components of tobacco smoke cause this?

Acombines with haemoglobin: carbon monoxide, constricts blood vessels in umbilical cord: nicotine

Bcombines with haemoglobin: carbon monoxide, constricts blood vessels in umbilical cord: tar

Ccombines with haemoglobin: tar, constricts blood vessels in umbilical cord: carbon monoxide

Dcombines with haemoglobin: tar, constricts blood vessels in umbilical cord: nicotine

✓ Correct answer

A: combines with haemoglobin: carbon monoxide, constricts blood vessels in umbilical cord: nicotine

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Topic: Coordination & Response, O-Level Biology (syllabus 5090). Multiple choice, 1 mark.
Source: O-Level Biology, May/June 2020 Paper 1 Variant 2, question 25.

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