biology 9.9 to 9.11

9.9 Explain the positive and negative human changes on ecosystems (fish farming)

• Fish farming pros: easy access to fish, meets the demand of fish, reduces overfishing of wild fish, reliable income for fish farmers

• Fish farming cons: loss of biodiversity, increased chance of disease as fish are kept in cramped conditions, uneaten food and faeces can contaminate surrounding water

9.9 Explain the positive and negative human changes on ecosystems (introduction of non-indigenous species)

• Introducing species pros: new species can be introduced to reduce a predator. E.g. cane toads introduced to kill crop-destroying beetles

• Introducing species cons: new species can flush out native ones if they bring disease. They compete with the native species for food, water, light and space which can result in one dying out.

9.9 Explain the positive and negative human changes on ecosystems (eutrophication)

• Eutrophication cons: Water becomes anoxic so aquatic animals die due to oxygen depletion, water bodies smell and look unpleasant due to algae, fishing industry fails as there is less fish in the rivers because of lack of oxygen

9.10 Explain the benefits of maintaining local and global biodiversity

Maintaining biodiversity is good because it keeps the ecosystem stable and reliable. Biodiversity supports fishing and tourism industries which boost the economy. Biodiverse ecosystems help humans, as a lot of plants and animals provide food and medicine to humans

9.10 Explain the impacts of reforestation and conservation of animal species

• Conservation of animal species helps prevent extinction. When animals go extinct there are big effects on the ecosystem; one species can destabilise it all. Additionally, maintaining animal diversity means that there is genetic diversity within populations. This is essential so that species can adapt to environmental conditions and diseases.

• Reforestation: restores habitats for wildlife that may have lost homes because of deforestation. Helps fight against climate change (more trees = more carbon absorbed, and more oxygen emitted)

9.11 describe biological factors affecting levels of food security

• New pests and pathogens = these can destroy crops and result in low food security

• Increased animal farming + meat and fish consumption = when more meat and fish are consumed, food resources that are already in low amounts become even more scarce, as the demand for them increases.

• Increased population = when the population gets bigger, more food is required. Countries often do not have the resources for this and this can lead to low food security