Practise 45 exam-style questions on Speciation (biology only) for AQA GCSE Biology. Write your answer as you would in the exam and get it marked in seconds against the mark scheme, point by point, with an AI tutor on hand if you get stuck.
45 questions
2–4 marks each
Instant marking
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20 questions, marked as you go
Sample questions with model answers
Here are 4 of the questions in this topic, each with a model answer, an explanation of why it earns the marks and the mark scheme an examiner would use.
Question 1
3 marks
Explain how a genetic bottleneck can affect genetic diversity and increase the chance of speciation.
Model answer
A bottleneck is a sharp reduction in population size causing loss of alleles by chance; survivors have reduced genetic diversity. If separated groups recover in different environments, genetic drift and selection may lead to divergence and speciation.
Explanation
Bottleneck reduces diversity; subsequent drift and selection in small or separate populations can cause divergence.
Mark scheme
1 mark
Bottleneck reduces population size and loses alleles (reduces genetic diversity)
Award for reduced diversity explanation.
1 mark
Genetic drift has greater effect in small populations (allele frequencies change by chance)
Award for drift concept.
1 mark
Different environments/selection after bottleneck can lead to divergence and speciation
Award for link to speciation.
Question 2
3 marks
Describe an example of sympatric speciation (non-polyploid) in animals or plants, and how it occurs.
Model answer
Example: Rhagoletis fruit flies (apple maggot). A host-shift to a new fruit (apples vs hawthorns) leads to assortative mating on host, different selection pressures and reduced gene flow, causing divergence without geographic separation.
Explanation
Sympatric speciation can occur by ecological niche shift leading to reproductive isolation via host preference or habitat assortative mating.
Mark scheme
1 mark
Example: Rhagoletis (apple vs hawthorn host races) or similar
Award for correct example.
1 mark
Speciation by host-shift/ecological divergence in same area
Mechanism.
1 mark
Assortative mating / reduced gene flow on different hosts leads to divergence
Final step to speciation.
Question 3
4 marks
Explain how sexual selection can drive speciation, with an example.
Model answer
Sexual selection is selection for traits that increase mating success (e.g., elaborate plumage). If different populations evolve different mating preferences or traits, assortative mating can reduce gene flow and lead to reproductive isolation and speciation. Example: stickleback mate choice based on colouration.
Explanation
Sexual selection can cause divergence of mating traits and preferences, reducing interbreeding and promoting speciation.
Mark scheme
1 mark
Sexual selection favours traits that increase mating success
Award for definition.
1 mark
Different populations can evolve different mating traits or preferences
Award for divergence in mating traits.
1 mark
Assortative mating / reduced gene flow leads to reproductive isolation
Award for mechanism to speciation.
1 mark
Example, e.g., stickleback colour choice or bird plumage differences
Award for a correct example linking sexual selection to speciation.
Question 4
4 marks
Explain how ecological opportunity and release from competition can lead to rapid speciation (adaptive radiation).
Model answer
When a lineage colonises an area with many available niches and low competition (ecological opportunity), natural selection favours adaptation to different niches. Divergent selection and isolation among niche-specialists leads to rapid speciation (adaptive radiation).
Explanation
Adaptive radiation occurs where ecological opportunity (new niches) allows multiple specialisations from a single ancestor, increasing speciation rates.
Mark scheme
1 mark
Ecological opportunity = many available niches / low competition
Definition.
1 mark
Population adapts to different niches (divergent selection)
Mechanism.
1 mark
Adaptations reduce competition and cause assortative use of different resources
Ecological release concept.
1 mark
Leads to rapid speciation (many specialized species from one ancestor)
Outcome.
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