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Topic 4: Evolution

6 dot points, in syllabus order. Each dot point has a focused answer, with exam-style questions and worked answers where available.

How does natural selection lead to adaptation over generations?

Explain natural selection and how it produces adaptation through differential survival and reproduction

Natural selection acts on heritable variation: individuals with favourable traits survive and reproduce more, so over generations advantageous alleles increase and populations become adapted.

8 min read →

How can we measure and predict genetic change in a population?

Explain allele frequencies and gene pools, and use the Hardy-Weinberg principle to detect change

A gene pool is all the alleles in a population; allele frequencies measure their proportions. The Hardy-Weinberg principle predicts frequencies in a non-evolving population so deviations reveal evolution.

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How is antibiotic resistance an example of natural selection in action?

Explain how antibiotic resistance in bacteria evolves through natural selection and how it spreads

Antibiotic resistance evolves by natural selection: a resistance mutation lets some bacteria survive antibiotics and reproduce, so resistant populations spread, worsened by antibiotic misuse.

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What other processes change allele frequencies besides natural selection?

Explain how genetic drift and gene flow change allele frequencies in populations

Genetic drift is random change in allele frequencies, strongest in small populations (bottleneck and founder effects); gene flow is the movement of alleles between populations by migration.

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What evidence shows that species share common ancestry and change over time?

Describe the lines of evidence that support evolution, including fossils, comparative anatomy, biochemistry and biogeography

Multiple independent lines of evidence support evolution: the fossil record, comparative anatomy (homologous structures), molecular biology (DNA and protein similarity) and biogeography.

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How do new species form from existing ones?

Explain how reproductive isolation leads to speciation, including allopatric speciation

Speciation is the formation of new species when populations become reproductively isolated and diverge; allopatric speciation occurs when a geographic barrier separates populations.

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