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SABiology

Topic 4: Evolution

6 dot points across 6 inquiry questions. Click any dot point for a focused answer with worked past exam questions where available.

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.
8 min answer →

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.
8 min answer →

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.
8 min answer →

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 answer →

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.
9 min answer →

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.
8 min answer →