Food supply
Methods to Increase Food Production
Humans have significantly increased food production to support a growing global population. This is achieved through several key agricultural methods:
| Method | How it works |
|---|---|
| Agricultural Machinery | |
| Chemical Fertilisers | |
| Insecticides | |
| Herbicides | |
Selective Breeding
Selective breeding is the process where humans choose parents with specific desirable characteristics to breed together, aiming to pass these traits to their offspring. This increases the proportion of individuals in the population that possess the desired alleles.
⚠︎ Confusing Herbicides and Insecticides
Error: Students often confuse herbicides with insecticides or fertilisers. They may state that herbicides kill pests or add nutrients to the soil.
Correct Understanding:
- Herbicides target weeds (unwanted plants) to reduce competition for resources.
- Insecticides target insects (pests) to prevent them from eating the crop.
- Fertilisers add mineral ions to the soil; they do not kill organisms.
Describing the Role of Chemicals
When asked to explain how a chemical increases food production, you must specify its target and the result.
- Context: Use this when explaining herbicides or insecticides.
- Reasoning: Examiners look for the link between reducing competition/damage and increased yield. Simply saying 'it helps plants grow' is too vague.
- Correct Usage: 'Herbicides kill weeds, which reduces competition for mineral ions and light, allowing crops to absorb more nutrients and increase yield.'
- Incorrect Usage: 'Herbicides provide food for the plants.' (This describes fertilisers).
Past Paper Style Questions
Q:
State one way humans use herbicides to increase food production. [1]
A:
To kill weeds / unwanted plants.
Q:
Explain how chemical fertilisers improve crop yields. [2]
A:
They provide essential mineral ions (e.g., nitrates) to the soil. This prevents nutrient deficiency and allows plants to grow larger/produce more biomass.
Large-Scale Monocultures
Monoculture is the practice of growing a single crop species over a large area. This is common in modern intensive agriculture.
Monoculture
Monoculture refers to the agricultural practice of cultivating a single crop species over a large area of land, rather than growing a variety of different plants.
⚠︎ Assuming Monoculture Always Increases Biodiversity
Error: Students sometimes think monoculture helps biodiversity because it 'protects' the crop.
Correct Understanding: Monoculture decreases biodiversity. By removing other plant species (using herbicides) and relying on one crop, the habitat for insects, birds, and other organisms is reduced. This makes the ecosystem less stable.
Balancing Advantages and Disadvantages
When asked for advantages/disadvantages, ensure you provide distinct points.
- Context: Use this when comparing monoculture to mixed farming.
- Reasoning: Examiners accept specific economic or ecological terms. Vague answers like 'good' or 'bad' receive no marks.
- Correct Usage (Advantage): 'Machinery can be used more efficiently because the field is uniform.' OR 'Less land is required to produce the same amount of food.'
- Correct Usage (Disadvantage): 'Pests can spread rapidly because all plants are susceptible.' OR 'Soil nutrients become depleted faster.'
Past Paper Style Questions
Q:
State one advantage of growing crops as a large-scale monoculture. [1]
A:
Easier to harvest using machinery.
Q:
State one disadvantage of growing crops as a large-scale monoculture. [1]
A:
Increased risk of pest infestation / disease spreading quickly.
Intensive Livestock Production
Intensive livestock production involves keeping animals in confined spaces (e.g., battery cages for chickens, indoor pens for pigs) with controlled conditions. The goal is to maximize meat/milk/egg output.
Intensive Livestock Production
Intensive livestock production is a farming method where animals are kept in confined spaces with controlled temperature and light, and fed high-energy diets to maximize the efficiency of energy transfer to biomass.
⚠︎ Misunderstanding Energy Efficiency
Error: Students often think intensive farming is inefficient because animals are 'stressed'.
Correct Understanding: Intensive farming is more energy-efficient for food production. In extensive farming, animals move around and maintain body temperature in cold weather, wasting energy as heat. In intensive farming, less energy is lost to movement/respiration, so more energy is available for growth (biomass).
Explaining the Energy Transfer Advantage
When explaining why intensive farming increases yield, focus on energy allocation.
- Context: Use this when asked to explain the biological advantage of keeping animals indoors.
- Reasoning: Examiners want to see the link between reduced energy loss and increased growth. You must mention 'movement' or 'respiration'.
- Correct Usage: 'Animals do not need to move around, so less energy is lost through respiration. More energy is transferred to biomass (growth), resulting in faster weight gain.'
- Incorrect Usage: 'Animals eat more food.' (This doesn't explain the efficiency).
Past Paper Style Questions
Q:
State one advantage of intensive livestock production. [1]
A:
Less energy is lost to movement / respiration.
Q:
State one disadvantage of intensive livestock production. [1]
A:
Poor animal welfare / ethical concerns.