CAIE IGCSE Biology 18.3.1 Natural Selection
Practise sequencing how inherited variation, competition and differential reproduction change allele frequencies over generations.
- Syllabus
- 2026–2028
- Course
- Biology 0610
Exam points
- start with genetic variation produced before the environmental selection pressure acts
- link competition and survival advantage to greater reproductive success
- explain how advantageous alleles become more common across successive generations
18.3.1—Natural selection with reference question 1
Sickle-cell anaemia is an inherited disease.
Fig. 5.1 is a photomicrograph of some blood cells from a person who has sickle-cell anaemia.
Fig. 5.1
Sickle-cell anaemia is most common in areas of the world where the infectious disease malaria is found.
Some species of the genus Plasmodium cause malaria in humans.
The distribution of sickle-cell anaemia is the result of natural selection.
Explain the distribution of the sickle-cell allele in human populations.
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