Inheritance, variation and evolution produce distinctive biology GCSE questions: Punnett squares, key terms, and extended explanations on natural selection.

Hub: Biology GCSE questions · Paper 2 focus.

Question types

Terminology (1–3 marks)

• Define the term allele.
• State what is meant by homozygous.

Precision beats long paragraphs.

Genetic crosses (4–6 marks)

• In mice, black fur (B) is dominant to white (b). Cross two heterozygous parents. Give the ratio of phenotypes expected.

Show gametes, offspring genotypes, then phenotype ratio. Check sex-linkage if the stem mentions sex chromosomes.

Describe DNA structure (3–4 marks)

• Describe the structure of a DNA molecule.

Double helix, complementary bases, sugar-phosphate backbone—match your spec’s depth.

Explain natural selection (4–6 marks)

• Explain how antibiotic resistance can evolve in bacteria.

Variation → selection → reproduction of resistant forms—not “bacteria want to survive”.

Evolution and classification

• Suggest why fossils provide evidence for evolution.

Compare ancient and modern forms; gradual change over time.

FAQ

Do I need to draw Punnett squares?

When the question asks for offspring probabilities, a clear square or systematic list is expected.

Common mistakes →

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