Scientists investigated three genetic variants in a species of flowering plant. Each variant arose from a different mutation.
In the first investigation, all plants were the same age and were grown for eight weeks with the same light, water, mineral ion supply and temperature.
| Variant | Evidence from the investigation |
|---|---|
| A | The 20 plants carrying variant A and the 20 plants without it both had a mean shoot height of 41.3 cm, a mean of 8.4 flowers and purple flowers. |
| B | All 20 plants carrying variant B had white flowers. All 20 plants without variant B had purple flowers. |
| C | The plants carrying variant C had a mean shoot height of 44.6 cm and a range of 36–52 cm. The plants without variant C had a mean shoot height of 39.2 cm and a range of 33–47 cm. |
State what changes when a mutation occurs.
Use the evidence in the table to assign each variant to one of these categories:
Explain your classification of variant C using the evidence in the table.
In a second investigation, plants carrying variant C were given a lower supply of mineral ions. Their mean shoot height was 35.8 cm.
A scientist concludes that variant C cannot increase shoot height because 35.8 cm is less than the 39.2 cm mean for plants without variant C in the first investigation.
Explain why this conclusion is not valid.
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.