Practise 33 exam-style questions on Extinction 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.
33 questions
3–5 marks each
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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 climate change can lead to species extinction through range shifts and mismatch of timing.
Model answer
As climate warms, species may shift their geographical range to track suitable conditions; if they cannot move, they decline. Climate change can also alter timing (phenology) of events like flowering or migration, causing mismatches between predators and prey or pollinators and plants, reducing survival and reproduction.
Explanation
Species unable to move or adjust their life cycles fast enough will experience reduced reproduction and survival. Mismatches can disrupt food chains and reproduction, pushing populations toward extinction.
Mark scheme
1 mark
Species shift range to follow suitable climate; inability to move causes decline
Range shift concept.
1 mark
Timing (phenology) changes e.g. earlier flowering or migration
Why can rapid environmental change caused by humans outpace the ability of species to adapt evolutionarily?
Model answer
Evolutionary adaptation requires many generations for advantageous mutations to spread; rapid human-caused change can be too fast relative to generation time, leaving species without time to evolve traits needed for survival.
Explanation
Evolution depends on selection across successive generations; if the environment changes faster than those generational changes accumulate beneficial traits, populations will decline.
Mark scheme
1 mark
Adaptation by natural selection needs many generations / time
Evolution timescale point.
1 mark
Human-caused changes can be rapid (fast pace)
Rate of change point.
1 mark
Result: species cannot evolve quickly enough and decline
Consequence linking speed and extinction.
Question 3
4 marks
Describe the roles of mutation and natural selection in producing a new species (speciation).
Model answer
Mutations produce genetic variation (new alleles). Natural selection acts on this variation, favoring individuals with advantageous traits. Over many generations, populations with different selective pressures accumulate genetic differences; reproductive isolation can result and new species arise.
Explanation
Random mutations create heritable differences. When environments differ, selection amplifies beneficial changes, leading to divergence; reproductive barriers eventually prevent interbreeding — forming new species.
Mark scheme
1 mark
Mutation generates genetic variation / new alleles
Accumulation of genetic differences between populations (over time)
Divergence point.
1 mark
Reproductive isolation leads to new species
Speciation completion.
Question 4
4 marks
Explain how hybridization with introduced species can threaten the genetic integrity and survival of a native species.
Model answer
Hybridization mixes gene pools; if hybrids backcross with the native species, unique native alleles may be diluted (genetic swamping). This can reduce local adaptations or cause outbreeding depression, lowering fitness and risking extinction.
Explanation
When foreign genes flood a native population through hybridization, the native genetic identity and adaptations can be overwhelmed, producing less-fit descendants and increasing extinction risk.
Mark scheme
1 mark
Hybridization mixes genomes of native and introduced species
Process description.
1 mark
Genetic swamping: native alleles diluted / lost over generations
Genetic integrity loss.
1 mark
Local adaptations can be lost or reduced
Adaptive consequence.
1 mark
Outbreeding depression or reduced fitness ? risk to survival
Fitness / extinction link.
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