O-LevelBiologyGenetics & Variation5090/12 · May/June 2020 · Q391 Mark

The inheritance of the ABO blood groups in humans is controlled by three alleles (IA, IB and Iº), only two of which can be present in one individual. What are the possible blood groups of children born to a homozygous group A woman and a heterozygous group B man?

AAB and B only

BAB and A only

CA, B and AB only

DA, B, AB and O

✓ Correct answer

B: AB and A only

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Topic: Genetics & Variation, O-Level Biology (syllabus 5090). Multiple choice, 1 mark.
Source: O-Level Biology, May/June 2020 Paper 1 Variant 2, question 39.

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