Biology: Human Influences on the Ecosystem

Question 1

List the undesirable effects of deforestation.

Answer 1

Extinction, loss of habitat, loss of soil, flooding, carbon dioxide build-up

Question 2

Describe the undesirable effects of pollution.

Answer 2

• water pollution by sewage and chemical waste

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

Question 3

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

Answer 3

Excessive amounts of nutrients are offloaded into lakes/rivers. This causes plants such as algae and duckweed to grow at a rapid speed. As the algae blooms, it covers the lake preventing sunlight reaching the bottom of the lake. When the plants die, the oxygen is depleted. Bacteria begin to decompose at a faster rate, thus using up even more oxygen from the water. Oxygen levels then reach a level where life is not possible therefore causing fish and other lifeforms to die.

Question 4

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

Answer 4

When sulphur dioxide and other nitrous gases released from processes such as burning fossil fuels, they dissolve into the clouds and cause acid rain. When the falls upon the Earth, the pH of the soil can change thus creating a loss of habitat on animals that fed on the grass that no longer grows due to the pH being too low.