Genetics, populations, evolution and ecosystems — AQA A-Level Biology
In summary: Genetics, populations, evolution and ecosystems is a key topic in AQA A-Level Biology. Key exam tip: Always define the variables when using the Hardy-Weinberg equation
Exam Tips for Genetics, populations, evolution and ecosystems
- Always define the variables when using the Hardy-Weinberg equation
- When describing natural selection, ensure you mention mutation, reproductive success, and changes in allele frequency over generations
- Use the term 'gene pool' when discussing changes in allele frequency
- Be precise with terminology: use 'species richness' and 'index of diversity' correctly
- When evaluating conservation, always link the management strategy to the specific ecological context
Common Mistakes
- Confusing genotype and phenotype
- Incorrectly applying the Hardy-Weinberg equation (e.g., failing to identify q² as the frequency of the homozygous recessive genotype)
- Assuming natural selection acts on individuals rather than populations
- Failing to mention reproductive isolation in the context of speciation
- Misinterpreting the assumptions of the mark-release-recapture method
- Confusing primary succession with secondary succession
Marking Points
- Definition of a population and species
- Application of the Hardy-Weinberg equation (p² + 2pq + q² = 1)
- Conditions required for the Hardy-Weinberg principle
- Mechanisms of natural selection (directional, stabilising, disruptive)
- Distinction between allopatric and sympatric speciation
- Role of genetic drift in small populations
- Use of quadrats and transects for population estimation
- Mark-release-recapture method and its assumptions
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