O-LevelBiologyTransport in Humans5090/11 · May/June 2025 · Q331 Mark

In the placenta, which substance passes from the blood of the embryo to the blood of the mother down a concentration gradient?

Aamino acids

Bcarbon dioxide

Cglucose

Doxygen

✓ Correct answer

B: carbon dioxide

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Topic: Transport in Humans, O-Level Biology (syllabus 5090). Multiple choice, 1 mark.
Source: O-Level Biology, May/June 2025 Paper 1 Variant 1, question 33.

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