Science Biology Energy Flow part 2


  • Created by: stephanie
  • Created on: 15-06-10 13:07

The Nitrogen Cycle

NITROGEN is an improtant element, vital for plant growth. It is also a vital componant in AMINO ACIDS and therefore PROTEINS.

Special NITROGEN-FIXING BACTERIA in the soil take nitrogen from the air and convert it into NITRATES found in the soil.

Plants take up nitrates in the soil. These are passed into animals when they are eaten.

When plants and animals die, special bacteria called DECOMPOSERS return the nitrates to the soil.

Through a series if steps, NITRIFYING and DENITRIFYING BACTERIA convert nitrates back into notrogen in the air.

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Problems With Fertilisers

Farmers use FERTILISERS to promote growth.

Fertilisers contain NITROGEN, an element essential in amino acids.

NITRATES are extremely SOLUBLE. When it rains, they are washed into the water systems.

The increased use of fertilisers has led to water systerms with unusually high levels of nirtates, This results in a process called EUTROPHICATION.

High levels of nitrates in lakes cause an increase in the growth of algae. This reduces the amount of light reaching the plants below water. As a result they die.

The decay of dead plant matter by microbes uses up much of the oxygen in the water and aquatic animal life dies. the dead animal matter makes the sisuation worse.

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Too Much Food

In some countries, farmers are given incentives to set fields aside. More food than is needed is being produced.

In many developing countries, there is insufficient food to feed the population. Drought and war add to the problem.

As the world's human population is increasing, we are placing enormace strains on the Earth to sustain ourselves.

Energy is lost through the food chain. By restricting energy transfer in out farm animals, we can reduce the amount of energy expenditure in farm animals by restricting theur movement and controlling the tempreture they live in.

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The Greenhouse Effect

Increased levels of CARBON DIOXIDE and METANE in the atmosphere cause the GREEN HOUSE EFFECT.

The greenhouse effect is a natural effect. Without it, the Earth would be much cooler.

GREENHOUSE GASES occur naturally through the release of gases from volcanoes and methane.

Burning FOSSIL FULES and DEFORESTATION are human activities which are resulting int he increase in Greenhouse gases .

Greenhouse gases act like a blanket around the Earth.

Heat from the sun is traped, causing the Earth's tempreture to rise.

Rising tempreture has caused the melting of the polar ice caps, resulting in a rise sea level.

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