Question 1
Triple only (what this means)
Triple only: only in Triple Biology. Combined Science students can skip it. What the labels meanExplain one advantage and one disadvantage of using fertilisers to increase crop yields.
Show mark scheme for question 1
- advantage: supply mineral ions / nitrates that plants need for growth (1)
- so crop yield increases (1)
- disadvantage: can be washed into rivers / lakes (1)
- causing water pollution / harm to wildlife (1)
- allow disadvantage: costly (1) so increases the farmer's costs (1)
- Max 3
Question 2
Triple only (what this means)
Triple only: only in Triple Biology. Combined Science students can skip it. What the labels meanLadybirds can be released in a greenhouse to control aphids. Explain one advantage and one disadvantage of using biological control instead of chemical pesticides.
Show mark scheme for question 2
- advantage: no chemical residue on the food / chemical pesticides not needed (1)
- so less harm to people or other organisms / the ladybirds target only the pest / keep working over a long time (1)
- disadvantage: slower / may not remove all the pests (1)
- allow disadvantage: the control organism may become a pest / eat other organisms (1)
- Max 3
Question 3
In a practice data set, a non-GM crop yields 5.0 tonnes per hectare. A GM crop yields 6.5 tonnes per hectare. Calculate the percentage increase in yield.
Show mark scheme for question 3
- (6.5 − 5.0) ÷ 5.0 × 100 (1)
- 30% (1)
Question 4
Evaluate the use of genetic engineering and selective breeding in modern agriculture. Include practical and ethical implications in your answer.
Show mark scheme for question 4
| Level | Marks | What the answer does |
|---|---|---|
| 3 | 5–6 | A balanced evaluation which covers benefits and risks of both methods, includes practical and ethical implications, and reaches a justified conclusion. |
| 2 | 3–4 | A partly balanced evaluation covering benefits and risks of both methods, or giving more detail for one method. Some practical or ethical implications are given. |
| 1 | 1–2 | A basic answer with one or two valid points. There is little or no evaluation. |
Indicative content
- selective breeding: higher yield, disease resistance, better quality food
- selective breeding: takes many generations, reduces genetic variation, so risk of disease affecting all
- genetic engineering: new characteristics such as insect resistance or higher nutritional value
- genetic engineering: quicker and more precise than selective breeding
- genetic engineering: costly, unknown effects on the environment or health, genes may spread to wild species
- ethical: some people think it is wrong to alter genes / interfere with nature
- ethical: concerns about animal welfare
- a justified conclusion, for example weighing increased food production against risks