Biology Unit 11: Human Influences on the Ecosystem

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Unit 11 Human Influences on the Ecosystem

1. List the undesirable effects of deforestation (to include extinction, loss of soil, flooding, carbon dioxide build up).

• Trees serve has habitats for animals; if they are cut down animals lose their homes and become more vulnerable to predators. The species will die out because they don't have a place to live

• Without trees, land is vulnerable to weather conditions that cause erosion

• Flooding will become easier because the land has no barriers that stop the water

• Trees use carbon dioxide in photosynthesis, and without trees the carbon dioxide levels in the atmosphere will rise

2. Describe the undesirable effects of overuse of fertilisers (to include eutrophication of lakes and rivers).

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3. Describe the undesirable effects of pollution to include: 

• water pollution by sewage and chemical waste, 

• air pollution by greenhouse gases (carbon dioxide and methane) contributing to global warming.

If chemical waste and rubbish flow into our seas, this basically makes the water unclean and makes it difficult for aquatic life to survive.

Carbon dioxide and methane are both greenhouse gases; greenhouse gases are the gases that absorb heat and reflect it back into the atmosphere, causing the world temperature to increase. This is bad for the environment as heat will cause ice at the Poles to melt, raising average sea levels.

4. Discuss the causes and effects on the environment of acid rain, and the measures that might be taken to reduce its incidence.

When sulphur dioxide and nitrogen oxides are released into the atmosphere, they mix with oxygen, water, and other chemicals. This causes acid rain. 

To reduce buildup that leads to acid rain, the burning of fossil fuels should be reduced. This is because combusting fossil fuels release both sulphur dioxide and nitric oxides. 

5. Explain how increases in greenhouse gases (carbon dioxide and methane) are thought to cause global warming.

This is similar to second point of point 3.

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6. Describe the need for conservation of: 

• species and their habitats, 

• natural resources (limited to water and non-renewable materials including fossil fuels).

Species need to me conserved because all specie are part of the food chain. If the food chain is disrupted, all species of the food chain will be affected, including humans. Their habitats must also be conserved to ensure they are able to survive.

Natural resources must be conserved because the Earth has only a limited amount. If all resources were to be used up, there would be none left for future generations. While fossil fuels can be produced again, it would take millions of years, and humanity doesn't have that much time to wait!