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biology 0610printed 292 · PDF 292
328 pagesrevision 46933
printed 292 · PDF 292
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Cutting down trees in large amounts to gather resources.
Deforestation has several negative effects:
Extinction and reduced biodiversity, species go extinct with less shelter and food
Soil erosion, without roots to hold soil, is carried away by wind and rain causing
decreased soil fertility.
Flooding, trees slow down water flow. Without trees, water moves swifter and thereby
also increases erosion
Increased carbon dioxide, with fewer trees less carbon dioxide is absorbed and more
is present in the atmosphere. Contributing to global warming
Pollution:
● Land, water and air pollution are all caused by human activity
● Raw sewage can be passed onto water bodies, chemicals can spread through the
water, endangering aquatic life and drastically reducing water quality
Pollution due to pesticides:
● Insecticides can kill other useful insects such as bees and pollinators.
● Herbicides are harmful to animals which eat the plants on which they are sprayed.
Herbicides can get washed into streams and kill aquatic organisms
Non-biodegradable plastics:
● Choke animals such as birds and fish
● Fill up animal stomachs, leaving little space for actual food
Eutrophication:
● Fertilisers are washed from fields into streams, thus increased nutrients in
waterways
● Plants grow rapidly and algae bloom caused
● Algae covers the surface of water, preventing sunlight from passing through and
decreased photosynthesis, thus killing them off
● Less oxygen released into water, dead plants broken down by decomposes which
use up a lot of the oxygen present in the water
● The lack of oxygen in the water kills fish and other animals
Air pollution:
● Main pollutants are methane and carbon dioxide
● Mostly due to fossil fuel burning