A breeder investigates variation in the growth of barley plants when water is limited. All plants are grown under the same conditions and receive the same limited volume of water.
| Parent plant | Increase in height in 21 days in cm |
|---|---|
| A | 3.2 |
| B | 8.4 |
| C | 2.9 |
| D | 7.9 |
The breeder crosses plant A with plant C and crosses plant B with plant D. The offspring are tested under the same limited-water conditions.
| Cross used to produce offspring | Mean increase in height of offspring in 21 days in cm |
|---|---|
| A × C | 3.5 |
| B × D | 7.6 |
Explain how the breeder could use these observations to produce a drought-tolerant variety of barley.
100 exam-style questions on Edexcel GCSE Biology 4.3 Selective breeding and genetic modification, covering 4.3.1 Selective breeding and its impact, 4.3.2 Tissue culture, 4.3.3 Genetic engineering overview, 4.3.4 Main stages of genetic engineering, 4.3.5 Advantages and disadvantages of GM organisms, 4.3.6 Agricultural solutions for a growing population, and 4.3.7 Evaluating genetic engineering and breeding. Each one has a worked solution and a mark scheme showing where the marks go.