Groups of sunflower plants with genotype L or genotype M are grown for six weeks. Each group receives either 8 hours or 16 hours of light per day. Other conditions are controlled.
| Genotype | Mean height with 8 hours of light per day / cm | Mean height with 16 hours of light per day / cm |
|---|---|---|
| L | 42 | 58 |
| M | 53 | 49 |
Which conclusion about daily light exposure is supported by these results?
Both genotypes reached the same mean height with 16 hours of light per day.
The mean height across the two genotypes was lower with 16 hours of light than with 8 hours.
The difference in mean height between the genotypes was greater with 16 hours of light than with 8 hours.
More daily light was associated with increased mean height for genotype L but decreased mean height for genotype M.
96 exam-style questions on Edexcel GCSE Biology 3.4 Variation and the Human Genome Project, covering 3.4.1 Causes of variation, 3.4.2 Outcomes of the Human Genome Project, 3.4.3 Genetic variation within a population, and 3.4.4 Effects of genetic mutations on phenotype. Each one has a worked solution and a mark scheme showing where the marks go.