O-LevelBiologyGenetics & Variation5090/11 · May/June 2015 · Q391 Mark

A person with Down's syndrome is born with 47 chromosomes in each cell, instead of 46. What could cause this?

Amutation happened during the production of the egg cell.

BMore than one sperm fused with the egg at fertilisation.

CRadiation caused a change in structure of a gene in the father's sperm.

DThe mother was exposed to harmful chemicals while she was pregnant.

✓ Correct answer

A: mutation happened during the production of the egg cell.

Oracle Prep sorts past-paper questions by topic, so you can drill Genetics & Variation and see which topics are most likely to come up next.

Topic: Genetics & Variation, O-Level Biology (syllabus 5090). Multiple choice, 1 mark.
Source: O-Level Biology, May/June 2015 Paper 1 Variant 1, question 39.

Questions and mark schemes are from past examination papers and remain the copyright of the exam board. How Oracle Prep builds its content