Selection and Evolution

Worked examples (5)

• 1Distinguishing continuous and discontinuous variation (5 marks)
• 2How meiosis generates genetic variation (5 marks)
• 3Standard deviation calculation (4 marks)
• 4Applying the t-test (5 marks)
• 5Genetic vs environmental variation (4 marks)

Model answers (5)

• ✓Model answer — 9700/42 May/Jun 2024 Q3 (adapted)
• ✓Model answer — 9700/42 Oct/Nov 2024 Q3(b) (adapted)
• ✓Model answer — 9700/42 May/Jun 2024 Q4 (adapted)
• ✓Model answer — 9700/42 Oct/Nov 2024 Q4(c) (adapted)
• ✓Model answer — Practice question — recurrent Paper 4 style

Worked examples (5)

• 1The Darwin–Wallace mechanism (6 marks)
• 2Peppered moth as directional selection (6 marks)
• 3Stabilising vs directional selection (5 marks)
• 4Antibiotic resistance as natural selection (6 marks)
• 5Natural vs artificial selection (5 marks)

Model answers (5)

• ✓Model answer — 9700/42 May/Jun 2024 Q4 (adapted)
• ✓Model answer — 9700/42 Oct/Nov 2024 Q5 (adapted)
• ✓Model answer — Practice question — recurrent Paper 4 style
• ✓Model answer — 9700/42 May/Jun 2024 Q6 (adapted)
• ✓Model answer — 9700/42 Oct/Nov 2024 Q6(b) (adapted)

Worked examples (5)

• 1Hardy-Weinberg — carrier frequency from disease incidence (6 marks)
• 2Hardy-Weinberg conditions and use as null hypothesis (5 marks)
• 3Allopatric speciation — Darwin's finches (6 marks)
• 4Allopatric vs sympatric speciation (4 marks)
• 5Genetic drift in small populations (5 marks)

Model answers (5)

• ✓Model answer — 9700/42 May/Jun 2024 Q7 (adapted)
• ✓Model answer — 9700/42 Oct/Nov 2024 Q7(b) (adapted)
• ✓Model answer — 9700/42 May/Jun 2024 Q8 (adapted)
• ✓Model answer — 9700/42 Oct/Nov 2024 Q8 (adapted)
• ✓Model answer — Practice question — recurrent Paper 4 style