Food Production and Sustainability

GCSE Biology · Ecology

Feeding the Growing Population

The growing global population requires increasing amounts of food. This has led to intensive farming practices and the search for sustainable methods of food production.

Factors Affecting Food Security

Food security means having enough nutritious food available and affordable for everyone. It is threatened by:

Population growth — more mouths to feed
Climate change — droughts, floods, and changing seasons reduce crop yields
Increasing wealth — changing diets (more meat) require more land and resources
New pests and pathogens — crop diseases reduce harvests
Environmental degradation — soil erosion, water shortages, pollution
Conflict and poverty — disrupt farming and food distribution
Cost of farming — seeds, fertilisers, equipment are expensive

Intensive Farming

Intensive farming aims to produce the maximum yield from the available land. Methods include:

Using fertilisers:

Artificial (inorganic) fertilisers provide plants with nitrates, phosphates, and potassium for faster growth
Organic fertilisers (manure, compost) also add nutrients and improve soil structure
Risk: eutrophication if excess fertiliser washes into waterways

Using pesticides:

Herbicides kill weeds (reduce competition for crops)
Insecticides kill insect pests (reduce crop damage)
Fungicides kill fungi (prevent disease)
Problems: can kill beneficial organisms (e.g. bees); can enter food chains and accumulate (bioaccumulation); pests can develop resistance

Controlling conditions in greenhouses:

Temperature, light, water, CO₂ levels, and mineral nutrients can all be optimised
Higher CO₂ and optimal temperature → faster photosynthesis → faster growth → higher yield
Pests and diseases are easier to control in enclosed environments
Expensive but very productive — used for tomatoes, cucumbers, strawberries

Factory farming (livestock):

Animals kept indoors in controlled conditions
Movement restricted — animals use less energy on movement → more energy goes into growth
Temperature controlled — animals do not need to use energy to keep warm
High-energy food provided
This increases the efficiency of energy transfer (biomass conversion)
Ethical concerns: animal welfare, use of antibiotics, disease spread

Efficiency of Food Production

Energy transfer through a food chain is inefficient:

At each trophic level, approximately only 10% of energy is passed to the next level
Energy is lost through: respiration (heat), excretion (urine, faeces), and parts not eaten (bones, roots)

Implications:

Eating plants (being vegetarian/vegan) is more energy-efficient than eating meat
It takes approximately 10 kg of plant feed to produce 1 kg of beef
Growing crops for human consumption uses less land and fewer resources than raising livestock

Sustainable Fishing

Overfishing has caused fish populations to decline dramatically. Sustainable methods include:

Fishing quotas — governments limit the amount of fish that can be caught
Net size regulations — larger mesh sizes allow young fish to escape and reproduce before being caught
Fishing seasons — banning fishing during breeding periods
Marine protected areas — zones where fishing is restricted or banned
Fish farming (aquaculture) — breeding fish in controlled enclosures; reduces pressure on wild stocks but can cause pollution and disease

Biological Control

Biological control uses living organisms to control pests instead of chemicals:

Examples:

Introducing ladybirds to eat aphids on crops
Using parasitic wasps that lay eggs inside caterpillars

Advantages	Disadvantages
No chemical pollution	The control organism may become a pest itself
Target specific pests	May not eliminate the pest entirely
Long-lasting — organisms reproduce	Can be difficult to control once introduced
No chemical resistance develops	May affect non-target species

Genetic Modification (GM) in Agriculture

Genetically modified (GM) crops have had genes from another organism inserted into their DNA to give them desired characteristics:

Pest resistance — e.g. Bt corn contains a gene from a bacterium that produces a toxin killing caterpillars
Herbicide resistance — crops survive herbicide spraying while weeds are killed
Improved nutrition — e.g. Golden Rice contains genes for beta-carotene (vitamin A precursor), helping prevent vitamin A deficiency in developing countries
Drought resistance — crops that grow in drier conditions

Arguments for GM crops	Arguments against GM crops
Higher yields → could help feed the world	Effects on wild ecosystems are unknown
Reduced pesticide use (pest-resistant crops)	GM genes could spread to wild plants (gene flow)
Crops with added nutritional value	Some people have concerns about eating GM food (although scientific consensus is they are safe)
Can grow in harsh conditions	Large corporations may control the seed supply

Selective Breeding

Selective breeding (artificial selection) involves choosing organisms with desired characteristics to breed together over many generations:

1. Choose individuals with the desired trait from the population

2. Breed them together

3. Select the best offspring with the strongest expression of the trait

4. Repeat over many generations