Biology Edexcel Topic 9 (Biodiversity and food security)

9.9 to 9.11

What is biodiversity

The variety of living organisms in an ecosystem

How does fish farming affect biodiversity

Food used to feed the fish and waste can leak into water sources, causing eutrophication, parasites from fish farms may spread and contaminate surrounding ecosystems and other organisms may become tangled in netting

How does the use of fertilisers affect biodiversity

Excess fertiliser can wash into water sources causing eutrophication and death of many species (reducing biodiversity)

Describe how fertilisers can cause eutrophication

Fertiliser run-off into rivers and lakes, nutrients build-up in water, algal bloom blocks sunlight meaning aquatic plants cannot photosynthesise so less oxygen produced, the plants die and decompose, decomposers further deplete oxygen levels so animals can no longer respire aerobically so die

How does the introduction of non-indigenous species affect biodiversity

They may out-compete the native species which causes a reduction in their population numbers, native species may become the prey of non-indigenous species, and they may bring new diseases which could kill large numbers of native species (which reduces biodiversity)

How can humans more positively impact biodiversity

Protection of endangered species (making hunting illegal), breeding programmes, conservation schemes (national parks, seed banks, zoos), reforestation, sustainable farming (fewer pesticides), and minimising global greenhouse gas production

What is reforestation

Replanting forests to help restore biodiversity

How do conservation schemes protect biodiversity

They prevent species from becoming extinct and increase population numbers, maintaining biodiversity

Outline the benefits of maintaining biodiversity

It ensures future food requirements can be met, reduces damage to food chains, increases the likelihood of species adapting to future environmental change, makes sure that new plants can be discovered which may contain chemicals that could be used in future medicines, valuable future resources will be saved, there will be jobs provided by ecotourism, reforestation and conservation schemes

What is food security

Ensuring that populations have access to adequate amounts of safe and nutritious food

List the biological factors affecting food security

Rising human population, changing diets, introducing new pests and pathogens, sustainability, and environmental changes

Describe how the rising human population affects food security

As human population increases, global food production must also increase to meet the growing demand for food

Describe how changing diets affects food security

Greater consumption of meat and fish in wealthier populations - less energy and biomass is available from livestock than crops, livestock also uses land for grazing and are fed crops that could otherwise be used for human consumption so less food is available for humans, leading to a reduction in food security

Describe how introducing new pests and pathogens affect food security

Pests and pathogens can reduce or destroy crop yields, negatively impacting food security

Describe how sustainability affects food security

Unsustainable farming methods disrupt food chains, compromising the ability to meet future food requirements due to the high input costs, using land for biofuel production reduces land available for crops

Describe how environmental changes due to human activity affects food security

Emissions of greenhouse gases have been linked to global warming which may affect crop growth, salinisation also reduces agricultural potential of soils