BiologyCode 5090
Effects of humans on ecosystems
What this topic asks you to be able to do
- Outline why deforestation happens and describe what it leads to, limited to its effects on: biodiversity, extinction, flooding, soil loss and atmospheric carbon dioxide concentration
- Describe the effects people cause via: (a) over-harvesting plant and animal species (b) bringing a non-native species into an ecosystem
- Describe the damage done by: (a) water pollution from untreated sewage and fertilisers containing nitrogen, which leads to eutrophication, limited to: (i) more nitrate and other ions becoming available (ii) producers growing more (iii) more decomposition once producers die (iv) more aerobic respiration by decomposers (v) less dissolved oxygen (vi) the death of organisms that need dissolved oxygen in water (b) greenhouse gases (carbon dioxide and methane) polluting the air, which adds to global warming, with the effects this is likely to have (c) pollution caused by herbicides and insecticides (d) plastics that are not biodegradable left in the environment, in aquatic and terrestrial ecosystems alike