Food SupplyCambridge IGCSE Biology: Revision notes
Section 1
How have humans increased food production?
Humans have increased food production in several ways:
- Agricultural machinery — prepares, plants and harvests land faster and on a larger scale.
- Chemical fertilisers — add nutrients (e.g. nitrates) directly to soil, boosting crop yield.
- Insecticides — kill insect pests that would otherwise damage or eat crops.
- Herbicides — kill weeds that compete with crops for light, water and nutrients.
- Selective breeding of crop plants and livestock — breeding individuals with desirable characteristics (e.g. higher yield, disease resistance, faster growth) over generations.
Section 2
Monocultures: advantages and disadvantages
A monoculture is the large-scale growing of a single crop species over a wide area.
Advantages:
- efficient use of machinery and labour, since all plants need the same care at the same time
- easier to plan planting, spraying and harvesting
- higher short-term yields
Disadvantages:
- reduces biodiversity, since natural habitats are replaced by a single species
- depletes the same soil nutrients repeatedly
- a single pest or disease can spread rapidly and destroy the entire crop, since there is no genetic variation to provide resistance
Don't say monocultures always increase biodiversity because they are 'organised' — the opposite is true, biodiversity falls because only one species is grown.
Section 3
Intensive livestock production: advantages and disadvantages
Intensive livestock production keeps large numbers of animals in a confined space to maximise output.
Advantages:
- higher yield of meat, milk or eggs per unit area or cost
- easier to control feeding, temperature and disease treatment
- lower cost of production, making food cheaper
Disadvantages:
- raises animal welfare concerns due to limited space to move
- disease can spread rapidly between animals kept close together
- produces large amounts of waste, which can pollute local water sources
Section 4
Managing food resources sustainably
A sustainable resource is one that is produced as rapidly as it is removed from the environment, so that it does not run out.
Two important food-related resources that can be conserved and managed sustainably are forests and fish stocks — both can keep providing food and materials indefinitely if harvesting does not exceed the rate of natural replacement.
Section 5
Conserving fish stocks
Fish stocks can be conserved through:
- education — informing fishing communities about sustainable practices
- closed seasons — banning fishing during breeding periods so populations can recover
- protected areas — marine reserves where fishing is restricted or banned
- controlled net types and mesh size — allowing young or small fish to escape and reach breeding age
- quotas — limiting the total mass or number of fish that can be caught
- monitoring — tracking stock levels to adjust the above measures
Larger mesh sizes in fishing nets let juvenile fish swim through and survive to breed, sustaining the stock for future years.
Must Know
- Food production has increased through machinery, fertilisers, insecticides, herbicides and selective breeding.
- Monocultures raise short-term yield but lower biodiversity and increase pest/disease risk.
- Intensive livestock production increases yield and lowers cost but raises welfare, disease-spread and pollution concerns.
- A sustainable resource is replaced as fast as it is used; forests and fish stocks are key examples.
- Fish stocks are conserved through quotas, closed seasons, protected areas, controlled mesh size, education and monitoring.
That's the notes covered.
Carry on to the next subtopic.