Variation and Selection

Worked examples (12)extended set

• 1Continuous or discontinuous? Classifying features
• 2Which process does not produce genetic variation? (multiple choice)
• 3Blood groups in a school: a bar chart of discontinuous data
• 4Measuring leaf length: a histogram of continuous variation
• 5Genetically identical plants grown in different light
• 6A change in the base sequence: describing gene mutation
• 7Sources of genetic variation
• 8Ionising radiation and the rate of mutation: an experiment
• 9Genes, environment or both? Explaining named examples
• 10Twins: separating the effects of genes and environment
• 11Snail shells at two sites: mean, range and causes
• 12Planning an investigation into leaf variation

Model answers (6)

• ✓Model answer — Paper 4 short-answer style
• ✓Model answer — Paper 4 short-answer style
• ✓Model answer — Paper 4 structured style
• ✓Model answer — Paper 4 (Extended) structured style
• ✓Model answer — Paper 4 (Extended) structured style
• ✓Model answer — Paper 4 (Extended) extended-response style

Worked examples (12)extended set

• 1What is an adaptive feature?
• 2Adaptive features of a desert rodent
• 3Floating leaf section: air spaces, stomata and cuticle
• 4A xerophyte leaf: describing then explaining its features
• 5Xerophyte features and their explanations (multiple choice)
• 6Stomatal density: converting units and identifying the habitat
• 7The adaptive features of a cactus
• 8Mass loss from two leaves: a practical comparison
• 9Ear size in foxes from different climates
• 10Adaptive features of a submerged pondweed
• 11Rolled leaves and humidity: explaining transpiration data
• 12One plant, two kinds of leaf: underwater and in air

Model answers (6)

• ✓Model answer — Paper 4 short-answer style
• ✓Model answer — Paper 4 short-answer style
• ✓Model answer — Paper 4 structured style
• ✓Model answer — Paper 4 (Extended) structured style
• ✓Model answer — Paper 4 (Extended) structured style
• ✓Model answer — Paper 4 (Extended) extended-response style

Worked examples (12)extended set

• 1Putting the stages of natural selection in order
• 2Selective breeding for sweeter tomatoes
• 3What do natural and artificial selection have in common? (multiple choice)
• 4Choosing parents to combine two useful features
• 5Insecticide resistance in mosquitoes
• 6Grain yield over ten generations of selective breeding
• 7Adaptation as a process: grasses on old mine waste
• 8Natural and artificial selection: the differences
• 9Simulating predation with coloured wool
• 10Thrushes and banded snails in two habitats
• 11A cloned crop and a new disease
• 12Breeding a pure-breeding herd of hornless cattle

Model answers (6)

• ✓Model answer — Paper 4 short-answer style
• ✓Model answer — Paper 4 short-answer style
• ✓Model answer — Paper 4 structured style
• ✓Model answer — Paper 4 (Extended) structured style
• ✓Model answer — Paper 4 (Extended) structured style
• ✓Model answer — Paper 4 (Extended) extended-response style