Crop Yields and Growing Conditions

IGCSE Edexcel Biology
5.1-5.4 Crop Plants and Food Production
Key Concept: Crop yield can be increased by controlling conditions such as temperature, light, and nutrient supply.

Section A: Glasshouses

1. Describe how glasshouses or polythene tunnels increase crop yield. [3]
2. Explain how increased $CO_2$ concentration increases crop yield. [2]
3. Explain how increased temperature in a glasshouse affects crop yield. [2]

Section B: Fertilisers and Pest Control

4. Explain how fertiliser use can increase crop yield. [2]
5. Give one advantage and one disadvantage of pesticides compared to biological control. [4]
Total marks: 13

Mark Scheme

1. Protect from weather/pests, trap heat, allow control of conditions, extend growing season (any three) [3]
2. $CO_2$ is a raw material for photosynthesis, so higher concentration increases rate/yield [2]
3. Higher temperature increases photosynthesis to an optimum, boosting growth [2]
4. Fertilisers supply mineral ions (nitrates, magnesium) for growth/protein/chlorophyll [2]
5. Pesticides act quickly and reliably but can harm non-target species or persist; biological control is specific but slower and may be harder to control (any one each) [4]