4.9 Carbon Cycle

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

1: photosynthesis      CO2 +  H20 --photosynthesis--> C6H12O6 + O2

                          

-photosynthesis- using chlorophyll therefore light energy is trapped to form organic molecules such as glucose. 

- carbon dioxide comes from the atmosphere and makes up 0.03% of the atmospheric gasses.

- photosynthesis is responsible for reducing the atmospheric CO2

2: feeding      producer ------> primary consumer.   

-producer eaten by primary consumers, so the primary consumer takes in the carbon of the producer and uses it to grow.

-the primary consumer is then eaten by the secondary consumer and the carbon passes along the food chain.
-all organisms are putting CO2 into the atmosphere through the process of respiration.  

3: respiration- at each stage in the food chain each organism carries out the process of respiration.

-C6H12O6 (glucose) + O2 (aerobic respiration) --breakdown using enzyme in the cells-> release of energy+ carbon dioxide + water.
-respiration adds CO2 to the atmosphere.

4: decomposition- eventually there will be the death of the producers, primary consumers and secondary consumers. the organic molecules that remain are broken down by the decomposer organisms (eg. bacteria and fungi) and it will result in a release in carbon dioxide in the atmosphere as well.

5: combustion- fossil fuels- formed over millions of years ago due to the compression of plants and animals forming oil, coal and natural gas are combustion to produce carbon dioxide eg. industrial/motor (cars, aeroplanes, lorries all combust fuels)

-environment- lightning strikes vegetation causing forest fi res causing carbon dioxide to get released into the atmosphere.

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 consequences.

-enhanced greenhouse effect caused by pollution such as CO2, CH4 (methane) and water vapour- GREENHOUSE GASES.

- gases increase concentration- cons= infrared light from the planet reemitted backwards towards the earth rather than escaping into space.

- global warming- increase in average temperature.

Consequences

-melting of ice caps in polar regions= more water in oceans (raised sea levels) so there is a:

-chance ocean currents

-chance in which the wind is generated.

-lead to larger picture- climate change

-raising the average global temp- result in changes in the distribution of the worlds biomes (major vegetation in the worlds ecosystems) 

4.13 Greenhouse gasses

understand how human activity contribute to greenhouse gases.
fossil fuels
-burning of fossil fuels results in the formation of more CO2, NO2, SO2 (carbon dioxide, nitrous dioxide being the greenhouse gasses)- absorb infrared light and redistribute back to earth.
- burning of fossil fuels from factories and vehicles, burning of coals, exhaust.

farming
-animals esp. cows emit methane into the atmosphere- around 9% of the atmospheric gases.

evaporation of water to form water vapour
-clouds are a significant contributor to the greenhouse effect.

refrigeration solvents and propellants
- CFCs- Chlorine Carbon and Fluorine- absorption of UV light and catalising the breakdown of the ozone layer.

4.12 Greenhouse Effect

recall that water vapour, carbon dioxide, nitrous oxide, methane and CFCs are greenhouse gases

(letters below represent the letters on the diagram)

a) UV light from the sun- short wave lengths or high energy.

b) 50% of light is reflected back into space- main cause is the clouds.

c) absorption on the earths surface- UV light converted and emitted as infrared.

d) infrared light (longer waves) emitted back outwards.

e) some of light is lost into space as heat.

f) some of the greenhouse gases- water vapour, carbon dioxide (CO2), methane (CH4)

-infrared light will hit the greenhouse gas and it will absorb the energy and it will re-emit it but in all directions including downwards to surface- which raises the surface temperature higher.

enhanced greenhouse effect.

-if we raised the levels of polluting gases (eg. CO2, CH4) then they will absorb more escaping radiation and emit it backwards towards earth- raising the temp- which leads to climate change.

-CFCs (chlorofluorocarbons)- well known for effect on ozone layer.

-Carbon Fluorine Chlorine.

-CCl3F -----sunlight----> CCl2F-+Cl-       =this breaks down O3 into O2.

-O3 is much better at absorbing UV light than O2.

4.11 Gas Pollution

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

sulphur dioxide
- SO2 gas added in the atmosphere by:

• combustion (burning) of fossil fuels eg. coal and oil in factories.
• vehicles- the combustion of oils and petrols and gas.

-sulphur dioxide (SO2) is combined with water (H2O) and forms sulphuric acid.

-sulphuric acid is found within the water which is in the cloud and when it rains, acid rain is produced.

-acid rain affects plants and animals:

• trees and plants are 'burned' by the sulphuric acid on the surface- usually top of tree is dead.
• calcium ions and magnesium which is obtained by the roots will be leached out of the soil- plants cannot obtain magnesium or calcium- causes yellowing of leaves and plants cannot grow.
• water of the rain will flow into streams and lakes this will reduce the PH (will make the lake acidic) aluminum ions will be released which has an affect on the fish- mucus on gills of the fish will be thickened by the aluminum ions- this will reduce the fish's ability to take oxygen from water... the fish suffocates and dies.

carbon monoxide

-CO (carbon monoxide) is produced when fossil fuels such as coal or gas are burned with insufficient oxygen.

-CO combines with haemoglobin inside red blood cells and forms a molecules called carbaminohemoglobin which blocks haemoglobin from carrying oxygen- reduce oxygen circulation. it is toxic- too much CO= fatal.

-it is difficult to get CO to be released from the haemoglobin.