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IGCSE Unit 22 Humans and the environment.2015-16
Transcript of IGCSE Unit 22 Humans and the environment.2015-16
The increase of heat trapped in the earth causes an average rise in sea level and temperatures, and we call this effect Global warming.
2. Overuse of fertilisers: undesirable effects
Species and their habitats
•Value to medicine: drugs come from plants
•Moral Issue: organisms have value in themselves
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1. Deforestation: undesirable effects
•Leaves the soil bare to erosion =>fertility lost and flooding.
3) They block sunlight and kill plants underneath.
3. Pollution: undesirable effects
Chemical waste and sewage in rivers → water is not drinkable and eutrophication can occur
Insecticides: can kill useful insects (pollinators).
Effects on Water
•Decreases pH => impacts the health and breeding success of aquatic animals.
Effects on Land
•Alters the pH of the crop => harming the plant.
Catalytic converters to remove sulphur-containing gases.
This process is called
Climate change => forests transpire more water than the soil alone
•Destroys habitats => extinction of some species.
•Less carbon dioxide consumed => global warming.
5) Fish and other creatures die from oxygen starvation
4) Bacteria/fungi decompose remains using the O
1) Fertilisers (nitrates/phosphates) leach into rivers/lakes after rain.
2) Water plants grow more than usual
Carbon dioxide and methane → greenhouse gases trap heat inside the atmosphere, contributing to global warming
Sulfur dioxide → lowers pH increasing acidity of lakes.
4. Effects on the environment of acid rain and prevention
•Dissolves metals out of rocks => increases the amount of metal affecting plants health.
•It can leach out minerals from the soil => unavailable for plants to use.
•Corrode metal structures and erode cement and limestone.
Vehicle emissions control reduces emissions of nitrogen oxides from motor vehicles
In factories lime (Calcium hydroxide) neutralises these acidic oxides.
5. Greenhouse gases (carbon dioxide and methane) and global warming.
•This is caused by some gases and we call this the Greenhouse effect.
•Some of the heat from the Sun is reflected back to the space and some is trapped in the Earth.
Herbicides (kill weeds): can be harmful to animals which eat the plants
Water: used to grow food, provide power, control fires, drink...
Fossil fuels: need to be conserved as they will soon run out.
We get fresh water through rainfall but we use up our planet’s fresh water faster than it can naturally be replaced.
Burning fuels and deforestation contribute to add greenhouse gases to the atmosphere