4.9 Carbon Cycle

4.9 Carbon Cycle

Describe the stages in the carbon cycle, including respiration, photosynthesis, decomposition and combustion

1) Photosynthesis -

Carbon dioxide comes from the atmosphere (0.03%)

When photosynthesis occurs it reduces the atmospheric Carbon dioxide

2) Feeding - Producer - Primary consumer (takes in carbon from the producer and reconstitute body material for growth) - Secondary consumer (carbon passes along the food chain). All levels in the food chain respire emitting carbon dioxide into the atmosphere.

3) Respiration - (for each stage in the food chain, each organism carries out the process of respiration)

(Begins with organic molecules; glucose). The process releases energy which is used for growth and movement. It also produces Carbon dioxide and water. Respiration adds carbon dioxide to the atmosphere.

4) Decomposition - All of the organisms in the food chain eventually die. The organic molecules are broken down by decomposer organisms known as bacteria and fungi. This causes the release of Carbon dioxide into the atmosphere as well.

5) Combustion -

1. Fossil fuels (formed millions of years ago due to the compression of plants and animals forming coal, oil and natural gas) are combusted to produce carbon dioxide. E.g. Industrial/motor (cars, aeroplanes, Lorries all combust fuels)

2. Environment- lightning striking vegetation causing forest fires causing carbon dioxide to get released into the atmosphere 

4.14 Enhanced Greenhouse effect

4.14 Enhanced Greenhouse effect

Understand how an increase in greenhouse gases results in an enhanced greenhouse effect and that this may lead to global warming and its consequences

Enhanced Greenhouse effect:

Pollution - molecules such as water vapour, carbon dioxide and methane (greenhouse gases) increase their concentration in the upper atmosphere.

As a result the infrared light would re-emit towards the surface of the Earth rather than it being released back out into space.

This raises the average global temperature which is known as global warming

Consequences:

-melting of ice caps in polar ice caps

-deserts would expand

-raised sea levels

-change of ocean currents

-winds

-coniferous forest's distribution would alter

These all contribute to the main factor of climate change.  There would be changes in the world's distribution of Biomes- major vegetation ecosystems.

4.12 Greenhouse effect

4.12 Greenhouse effect

Recall the water vapour, carbon dioxide, nitrous oxide and CFC's are greenhouse gases

4.13 Greenhouse gases

4.13 Greenhouse gases

Understand how human activities contribute to green house gases

Fossil Fuels:

1) Industrial (factories)

2) Cars

3) Domestic

The burning of fossil fuels causes the release of Carbon dioxide, nitrous dioxide and sulphur dioxide. These are known as greenhouse gases. These gases in upper atmosphere absorb infrared light and redistribute the gases to the surface of the planet.

Farming- Animals (cows) when digesting crops emit Methane gas into the atmosphere. It is a significant contributor to the greenhouse gases- almost 9%

Evaporation of water- forms water vapour- clouds are also adds to greenhouse gases

Refrigeration/solvents/propellants- known as chlorofluorocarbons (CFC's).  A combination of Chlorine, Carbon, and Fluorine (Cl₃F)

4.11 Gas pollution

4.11 Gas pollution

Understand the biological consequences of pollution of air by sulphur dioxide and by carbon monoxide

1)      Sulphur dioxide – SO₂

The gas is added to the atmosphere when the combustion of fossil fuels (coal, oil and natural gas) occur in factories. (Sulphur dioxide is also produced from vehicles)

In the atmosphere Sulphur Dioxide combines with water vapour to produce Sulphuric Acid.

Sulphuric acid is found within water (in clouds) and when it rains it is known as acid rain.

Effects of Sulphur dioxide:

-Animals (the aluminium ions have an effect on fish; it thickens the mucus that lines the gills and reduces the fishes intake of oxygen from the water. The fish in turn suffocates and eventually dies.

-Lakes (the rain will forms streams, which will grow to form lakes. Acid rain reduces pH (make them acidic) and releases aluminium ions.

-Forests (trees and plants are 'burned' by the acid rain)(root system- Sulphuric acid causes the calcium and magnesium ions (Ca2+ and Mg2+) to be leeched out of the soil. The plant cannot obtain either magnesium or calcium; therefore yellowing of leaves occurs/the plant cannot grow.

2) Carbon Monoxide

It is produced when fossil fuels (especially gases) are burned with insufficient oxygen. CO combines with the hemoglobin in the red blood cells and forms a molecule called Carbonmino hemoglobin. It blocks the hemoglobin from carrying oxygen.

Effects of CO:

-Reduces oxygen circulation

- Toxic

- Too much of it can cause death

- It is very difficult to separate the Carbon monoxide molecule from the hemoglobin