CAIE IGCSE Biology 20.4.9 Risks to a Species If Its Population Questions

Practise explaining how small populations lose genetic variation and face inbreeding, poor adaptation and extinction risk.

Exam points

link falling population size to a smaller gene pool and reduced genetic variation
explain how inbreeding increases homozygosity and expression of harmful recessive alleles
connect low variation to weaker adaptation, disease vulnerability and higher extinction risk

[Maximum number: 3]

Steppe ecosystems are large areas of grasslands found in central Asia.

Fig. 4.2 is a photograph of a wild horse. Przewalski's horse is a type of wild horse that nearly became extinct.

After a captive breeding programme, they were successfully reintroduced to the steppe ecosystem.

The captive breeding programme started with 12 wild horses.

Fig. 4.2

Explain the risks to a species of a captive breeding programme that uses such a small number of individuals.

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CAIE IGCSE Biology 20.4.9 Risks to a Species If Its Population Questions question 1