Wheat stem rust is a disease of wheat plants. It is caused by a fungus.
A new type of the fungus has spread from Africa to many other countries.
Scientists measured the yield of wheat in fields with and without the new type of fungus.
The Table shows the results.
Table
| Field | Yield of wheat in tonnes per hectare |
|---|---|
| without the fungus | 8.0 |
| with the fungus | 5.0 |
Calculate the percentage decrease in yield caused by the fungus.
Explain why the spread of a new pathogen like this could reduce food security.
Farmers could spray the wheat with a chemical that kills the fungus.
Suggest one other way farmers could reduce the effect of the fungus on wheat yields.
Scientists have found a wild grass that is resistant to the new fungus.
They want to put the gene for resistance from the wild grass into wheat using genetic engineering.
Suggest two advantages of using genetic engineering rather than selective breeding to do this.
127 exam-style questions on OCR GCSE Biology 6.2 Feeding the human race, covering 6.2.1 Biological factors affecting food security, 6.2.2 Agricultural solutions to growing demand, 6.2.3 Selective breeding, 6.2.4 Genetic engineering, 6.2.5 Steps in genetic engineering, 6.2.6 Benefits and risks of gene technology in agriculture, and 6.2.7 Biotechnological solutions to growing demand. Each one has a worked solution and a mark scheme showing where the marks go.