Edexcel iGCSE Biology L5th/M5th - Human Influences On The Environment

Deforestation

This is the cutting down of large number of trees for fuel and farmland

Acid rain

Is when the sulphur dioxide and nitrogen oxide produced when sulphur containing fossil fuels are burnt and nitrogen present in vehicles react with oxygen in the air, respectively react with water to form sulfuric acid and nitric acid, which makes it more acidic (pH drops) and thus falls in the form of this

Global warming

It is the increase in the earth's average temperature

Green house effect

The sunlight comes to earth by passing through the atmosphere, but some of this sunlight is reflected back after reaching the ground (infra-red radiation). The carbon-dioxide in the atmosphere, forms a blanket which re-radiates some of the heat energy back to Earth. Thus this keeps the heat trapped within the earths atmosphere, just like a greenhouse used for plants in cold countries.

Green house gases

The gases that act as a blanket around the earth's atmosphere, which keeps the earth warm. The most important examples are carbon-dioxide and methane.

Fossil fuels

They are naturally occurring resources burnt for fuel and energy (ex: coal, oil (petroleum), natural gas)

Eutrophication

An algal bloom blocks light to the lower depths of a body of water resulting in plants lower down dying. Bacteria which respire aerobically decompose the dead plants, and therefore reproduce rapidly due to the plentiful dead matter. This large population of aerobic bacteria use up oxygen from the water. Thus there will be less oxygen for other living things, such as fish, to die.

Leaching

When nitrate/phosphate containing fertilisers are put onto soil and it rains these leached nitrates may run into streams & rivers.

Fertilisers

Contain minerals for plants, but if there is excessive contact with water, it can lead to eutrophication.

Organic

Fertilisers like manure which are from living things.

Inorganic

Fertilisers which are manufactured like ammonium nitrate that are normally sprayed in solution. Can be leached and damage soil structure.

CFC's

Chlorofluorocarbons. Man made chemicals used as coolants and propellants in aerosols. Potent greenhouse gases that also lead to depletion of the ozone layer.

Carbon monoxide

a colorless, odorless, and poisonous gas leads to the formation of carboxyhaemoglobin and reduces the oxygen carrying capacity of red blood cells

Fish farming

Form of aquaculture in which fish are cultivated in a controlled pond or other environment and harvested when they reach the desired size

Infraspecific

individuals of the same species compete for a resource

Interspecific

competition between members of different species

Anoxic

do not have oxygen available to plants or invertebrates

Selective Breeding

Method of breeding that allows only those individual organisms with desired characteristics to produce the next generation.