Edexcel IGCSE Biology · Spec 3.26-3.27
Sex Determination
How the X and Y sex chromosomes determine whether offspring are male or female.
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Sex Determination
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Spec 3.26-3.27
What you need to know
- Know that sex is controlled by the sex chromosomes
- Recall that females are X X and males are X Y
- Use a genetic diagram to show the fifty-fifty ratio
Active recall
Quick check
Answer each question before opening the answer.
What are the sex chromosomes of a human male and female?
Male: XY. Female: XX.
What is the probability that a baby is a boy?
50% (1 in 2).
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