All genetic variants arise from mutations.
The Table describes three mutations. The effect of mutation X on the phenotype has been done for you.
Table
| Mutation | Description | Effect on the phenotype |
|---|---|---|
| X | a mutation in the DNA of a mouse; the mouse looks and works in exactly the same way as other mice | has no effect |
| Y | a mutation in one gene of a fruit fly; the fly always develops curly wings | |
| Z | a mutation in one of the many genes that affect human height; the person is slightly taller than expected |
State what is meant by a mutation.
Use words from the list to complete the Table for mutations Y and Z.
determines influences has no effect
Most phenotypic features are the result of multiple genes.
Explain why mutation Z only has a small effect on height.
A student says:
'All the variation between people is caused by mutations.'
Explain why the student is not fully correct.
186 exam-style questions on OCR GCSE Biology 5.1 Inheritance, covering 5.1.1 The genome, 5.1.2 Environment and phenotype, 5.1.3 Variants and mutations, 5.1.4 How genetic variants influence phenotype, 5.1.5 Asexual and sexual reproduction, 5.1.6 Haploid and diploid, 5.1.7 Meiotic cell division, 5.1.8 Single gene inheritance, 5.1.9 Predicting single gene crosses, 5.1.10 Sex determination, 5.1.11 Multiple gene inheritance, and 5.1.12 Development of our understanding of genetics. Each one has a worked solution and a mark scheme showing where the marks go.