Variation — AQA GCSE Biology
Test yourself on Variation with AQA GCSE practice questions.
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Variation explained
The genome is the entire genetic material of an organism.
Read the full explanation
Genes within the genome code for proteins that help build and control the organism, so the genome provides the instructions that influence characteristics such as eye colour, blood group and height potential. However, the phenotype is not fixed by genes alone. The environment interacts with the genome throughout development. For example, a person may inherit genes for tall stature, but nutrition during childhood affects how tall they actually grow. Plant height depends on genes and on light, water and mineral availability. Some characteristics, such as blood group, are determined mainly by genes, while others, such as body mass or language spoken, are influenced strongly by the environment. The phenotype is therefore the result of both genetic instructions and environmental conditions.
Your focus
- Define the genome and state that genes code for proteins.
- Describe how the genome and the environment interact to influence the phenotype.
- Apply the idea of gene-environment interaction to a named example of a characteristic.
Variation exam tips
Marking Points
- Define the genome as the entire genetic material of an organism.
- State that genes code for proteins that influence the development of characteristics.
- Explain that the phenotype is influenced by the genome and by environmental factors.
- Give an example where both genes and environment affect a characteristic, such as height being influenced by genes and nutrition.
- Recognise that some characteristics are determined mainly by genes, while others are influenced strongly by the environment.
- Describe the interaction as the combined effect of genetic instructions and environmental conditions during development.
Examiner Tips
- 💡Use the terms genome, gene, phenotype and environment accurately in your answer.
- 💡Include at least one named example where genes and environment both affect a characteristic.
- 💡Explain the interaction rather than listing genes and environment separately.
Common Mistakes
- Saying the environment changes the genome itself; the environment affects how genes are expressed and how the organism develops, not the DNA sequence.
- Treating phenotype as determined only by genes; both genetic and environmental factors contribute.
- Confusing the genome with a single gene; the genome is the entire genetic material, not just one gene.