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Edexcel IAL Biology 4.20 Hardy-Weinberg and speciation

Define p and q from the data, show each squared or heterozygote term and connect observed frequency change or isolation to selection, gene flow or speciation.

Syllabus
First assessment 2019
Course
Biology YBI11
Level
AS

Exam points

  • Calculate p, q, p-squared, 2pq or q-squared accurately from population evidence.
  • Explain how corridors or population mixing change gene flow and genetic diversity.
  • Explain speciation through isolation, selection and accumulated allele differences.

4.20—Hardy-Weinberg, allele frequency and speciation question 1

[Maximum number: 2]

The photograph shows a mother and baby Malayan tapir (Tapirus indicus). They live in the rainforests of southeast Asia. Each gamete of a Malayan tapir contains 26 chromosomes.

Figure for Question 4.20—Hardy-Weinberg, allele frequency and speciation question 1 — Edexcel A-Level Biology AS

© Sipa US / Alamy Stock Photo

Biodiversity within a species can be measured using genetic diversity. Three melanistic Malayan tapirs have been discovered that have black fur all over their bodies. Melanistic tapirs have two copies of the recessive allele for fur colour and are homozygous.

Explain how scientists could determine if a change in the frequency of the recessive allele was occurring over time.

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