Slugs feed on potato plants and reduce the yield of potatoes.
A species of nematode is a parasite of slugs. The nematodes enter slugs, reproduce inside them and kill them.
Growers compared pesticide pellets with these nematodes at four farms during one growing season. At each farm, each method was used on five equal-sized plots. The Table shows the mean yield from the plots.
| Farm | Mean yield using pesticide pellets in tonnes per hectare | Mean yield using nematodes in tonnes per hectare |
|---|---|---|
| A | 42.0 | 44.0 |
| B | 38.5 | 37.5 |
| C | 46.0 | 48.5 |
| D | 41.5 | 43.0 |
The total cost of buying and applying the pesticide pellets is £55 per hectare. The total cost of buying and applying the nematodes is £115 per hectare.
A grower sells potatoes for £180 per tonne and has 24 hectares of potato fields.
Calculate the predicted increase in the grower's income after control costs if the grower uses nematodes on all 24 hectares instead of pesticide pellets.
Use the mean yields from all four farms.
A supplier makes this claim.
“These results prove that using nematodes will increase the grower's income after control costs every growing season.”
Evaluate this claim.
Use your answer to (a) and evidence about the trial.
Explain how a fall in slug numbers could later lead to slug numbers rising again when nematodes are used.
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.