Practise 30 exam-style questions on Variation 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.
30 questions
1–4 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
2 marks
What is meant by the statement 'there is usually extensive genetic variation within a population'?
Model answer
Most individuals in a population have different alleles/genes for many traits, so many different variants of characteristics exist.
Explanation
Within a species population, genetic diversity means individuals carry different versions of genes, producing a range of phenotypic variants.
Mark scheme
1 mark
Individuals have different alleles/genes
1 mark
So many different variants of traits in a population
Question 2
2 marks
Why is genetic diversity important for conservation of species?
Model answer
Greater genetic diversity increases the chance some individuals can survive environmental changes or disease; reduces inbreeding problems.
Explanation
Genetic diversity provides the variation necessary for selection to act on, increasing resilience of populations.
Mark scheme
1 mark
Increases chance of survival under environmental change / disease resistance
1 mark
Reduces inbreeding depression / problems
Question 3
3 marks
A rare mutation gives resistance to a pesticide. Describe how the frequency of the resistance allele changes if the pesticide is used heavily, and then if its use stops.
Model answer
With heavy pesticide use, resistant individuals survive and reproduce, so the resistance allele increases in frequency. If pesticide use stops, resistant individuals no longer have an advantage and allele frequency may decrease due to selection against any cost of resistance or genetic drift.
Explanation
Selection increases beneficial allele frequencies under the selective pressure; removing the pressure can reduce the advantage and frequency may decline.
Mark scheme
1 mark
Heavy pesticide use ? resistant individuals survive and reproduce
1 mark
Resistance allele frequency increases
1 mark
If pesticide use stops allele frequency may fall (no advantage / possible cost of resistance)
Question 4
3 marks
Explain how a beneficial mutation could spread through a population by gene flow rather than by selection.
Model answer
If individuals carrying the mutation migrate to other populations, they bring the allele with them; repeated migration (gene flow) increases the allele frequency in the recipient population even without strong selective advantage.
Explanation
Gene flow transfers alleles between populations; sustained movement can change allele frequencies even in absence of selection.
Mark scheme
1 mark
Migration of individuals carrying the allele into other populations
1 mark
Allele introduced increases in frequency by repeated arrivals (gene flow)
1 mark
Can spread without selection if migration rate is high
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