Exam Focus

Exam Focus

Evolution by natural selection is one of the most commonly examined topics in AQA Biology Paper 2 and Edexcel 1BI0/1 (Paper 1). These areas come up most often:

• 6-mark extended response: "Explain how a population of organisms could evolve over time through natural selection." Use the VISA structure — Variation, Inheritance, Selection, Accumulation — and write in full sentences.
• Antibiotic resistance (3-4 marks): The bacteria question is a near-annual fixture. Always start from variation (mutation), not from the antibiotic appearing. The antibiotic selects — it does not cause the mutation.
• Darwin vs Lamarck (2 marks): Be able to state both theories clearly and explain why Lamarck is wrong (acquired characteristics are not encoded in DNA and cannot be inherited).
• Evidence for evolution (2-3 marks): Name the type of evidence AND explain what it shows. "Fossils — show how organisms have changed over time" scores more than just "fossils."
• Command word "explain": Always link survival to reproduction and then to inheritance. "Survives more" alone scores 0 — you must say why surviving individuals pass on the allele.

Edexcel 1BI0 style: Edexcel Paper 1 (1BI0/1) often uses a novel organism or unfamiliar scenario as stimulus for evolution questions — for example, a passage about the evolution of antibiotic resistance in a specific bacterial species, or data on changing beak size in a bird population. Apply the VISA steps to the specific context given. The command word "Suggest" is common here: "Suggest how the antibiotic-resistant bacteria became more common." Extended 6-mark responses must reference BOTH the stimulus information AND your own knowledge — citing the given data (e.g., survival percentages, time periods) demonstrates AO3 analysis skills alongside AO1 knowledge.