GCSE BIOLOGY REVISION: BIODIVERSITY AND THE EFFECT OF HUMAN INTERACTION ON ECOSYSTEM
Please note: Text in bold is what the AQA GCSE biology specification requires an understanding of.
Pollution can occur:
in water, from sewage, fertiliser or toxic chemicals
in air, from smoke and acidic gases
on land, from landfill and from toxic chemicals.
Pollution kills plants and animals which can reduce biodiversity.
In various parts of the world, open sewers can lead into water courses (for example rivers and streams) which can then lead to serious illnesses for people that drink the contaminated waters. Contamination can occur through various routes…
Farmers using too many fertilisers is a concern for the environment. When it rains, the fertilisers used that are in the soil run off and end up in water ways. This can pollute these nearby rivers and streams. This is known as eutrophication. At this point, plants flourish as pollutants cause vast aquatic plant growth of algae, duckweed and other plants. With algae blooms leads to oxygen depletion, and prevention of sunlight reaching other plants inside the water. Thus, these plants die as they cannot receive sunlight or oxygen. Next step, decomposition. This further depletes oxygen as dead plants are broken down by bacteria that use the remaining oxygen in the water to do so. The end result; death of the ecosystem. The oxygen levels reach a point where life is not possible, so fish and other organisms die. Additionally, water pollution can sometimes arise from toxic chemicals being illegally released by factories.
Combustion is the process of burning something. When fossil fuels and other fuels are combusted, carbon dioxide is released. This carbon dioxide release contributes to the greenhouse gas effect which is a leading cause of global warming. Sulphur dioxide and nitrogen oxide can also be released from burning fuels, these gases are causes for acid rain. Air pollution can also be caused by tiny air particulates from smoke, this can be a cause for smog. Major cities like Delhi and Beijing have reached dangerously high levels of air pollution.
Ever think about where your rubbish may end up? If the rubbish we throw away is not recycled then it goes into a land fill. Landfills are huge holes in the ground where rubbish is deposited. There are items that cannot be placed in landfill sites, for example batteries. This is because of the toxic chemicals they contain. So remember, if you see on the packaging that your item is meant to be disposed in a certain way, listen to what you are instructed to do! They will need to be recycled. Fly tipping, which is illegal, is the process of dumping rubbish in public or private places without paying.
When the human population rises, more land is required. More houses need to be built, more resources, more food and of course more waste. This means less space available for resources, animals and plants. Clearing land for human development leads to reduction in biodiversity.