O-LevelBiologyGenetics & Variation5090/12 · Oct/Nov 2019 · Q391 Mark

The diagram shows a family tree in which hereditary night-blindness occurs. [Figure 39.1] What is the chance that unborn child, 9, will be a male with night-blindness?

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A1 in 2

B1 in 4

C1 in 8

D3 in 4

✓ Correct answer

C: 1 in 8

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Topic: Genetics & Variation, O-Level Biology (syllabus 5090). Multiple choice, 1 mark.
Source: O-Level Biology, Oct/Nov 2019 Paper 1 Variant 2, question 39.

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