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VCE Units 1–4 · Biology

VCE Biology — Evolution and Biodiversity

Evolution and biodiversity covers how life on Earth has changed over time and the mechanisms driving those changes. In VCE, this includes natural selection, speciation, phylogenetics and the evidence for evolution. Exam questions often require students to apply the process of natural selection to an unfamiliar scenario — not just recall the definition.

Key Concepts & Formulas

  • Natural selection requires: variation in a population, heritability of variation, differential survival/reproduction based on that variation

  • Selective pressure: an environmental factor that affects the survival of individuals with certain traits

  • Individuals do NOT evolve — populations evolve over many generations as allele frequencies change

  • Allele frequency change over time: beneficial alleles increase in frequency; harmful alleles decrease

  • Speciation: the process by which new species form; requires reproductive isolation

  • Allopatric speciation: geographic isolation separates populations → different selective pressures → diverge into separate species

  • Sympatric speciation: speciation without geographic isolation (less common); e.g. via polyploidy in plants

  • Phylogenetic trees: diagrams showing evolutionary relationships; closer branching = more recent common ancestor

  • Evidence for evolution: fossil record, comparative anatomy (homologous and analogous structures), biogeography, molecular evidence (DNA similarity)

  • Homologous structures: same evolutionary origin, different function (e.g. human arm and whale flipper)

  • Analogous structures: same function, different evolutionary origin (e.g. bird wing and insect wing) — evidence of convergent evolution

Practice Questions

5 questions

Attempt each question before reading the hint. These are styled to match VCE exam format.

Q1.A population of bacteria is exposed to an antibiotic. Explain, using the principles of natural selection, how antibiotic resistance can develop over time.

4 marks

Q2.Distinguish between allopatric and sympatric speciation. Give one example of each.

4 marks

Q3.Explain why homologous structures provide stronger evidence for common ancestry than analogous structures.

3 marks

Q4.A phylogenetic tree shows species A and B sharing a common ancestor 50 million years ago, while species A and C share a common ancestor 10 million years ago. Which two species are most closely related? Justify your answer.

2 marks

Q5.Explain the Lamarckian view of evolution and describe ONE piece of evidence that refutes it.

3 marks

Common Mistakes to Avoid

These are the errors that VCE students most frequently make in Evolution and Biodiversity — and that examiners are specifically watching for.

  • Stating that individuals "adapt" during their lifetime — Lamarckian error; only populations evolve over generations

  • Saying natural selection "creates" variation — variation must pre-exist in the population; natural selection only acts on existing variation

  • Confusing homologous and analogous structures — homologous = same origin, different function; analogous = different origin, same function

  • Reading phylogenetic trees incorrectly — the number of branching points between species, not their positions on the diagram, indicates relatedness

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