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.

4.7 Energy Efficiency

explain why only about 10% of the energy is transferred from one trophic level to the next

-pyramid of energy  ->

-out of 100% of producers only 10% makes it to the primary consumer level and only 1% (out of the 100%) makes it to the secondary consumer level.

-causes of losses:

-100kj of grass energy eaten by herbivore.

-of 100kj of energy eaten by the mouse only 10kj (of the original 100kj) will be part of the mouse body and tissue (bones, eye, muscles, skin, fur etc..)

-REASON- mice has to walk around and find food. they need to respire.

-energy will be lost by respiration.

-not all 100kj of energy is available to the mice. mice cannot digest cellulose (cell wall) but cellulose contains energy- energy lost by feces.

-since 10kj is gained from mice eating 100kj of grass, 90kj of energy is lost by respiration and undigested food.

-when the owl eats the mouse only 1% of the original 100% will make it this far, so the owl gets 1kj out of 100kj (10% rule)

-losses are from respiration, producing energy for flight, movement, digestion etc.

-not all of the mouse is available to the owl. can't digest all- lost by feces.

-all organisms will die at some point- they will broken down by micro-organisms which live by the dead and decaying remains of other organisms- called decomposers.

4.6 Energy and substances in food chains.

understand the transfer of substances and of energy along a food chain.
-bush grass being eaten by the impala.
-bush grass- producer
-impala- primary consumer
-leopard- secondary consumer
-lion- tertiary consumer (if the lion eats the leopard)

-producer- converting light energy to chemical energy - chemical energy takes the form of organic molecules (carbohydrates, protein, lipids) molecules are food.

-molecules are composed of:
C-H  (carbon to hydrogen bonds)
C-O  (carbon to oxygen bonds)
C-C  (carbon to carbon bonds)
O-H  (oxgen to hydrogen bonds)
C-N  (carbon to nitrogen bonds)
-these bonds all represent energy.

-C, H, O, N (carbon, hydrogen, oxygen, nitrogen) are the substances/matter.
-as bush grass carries out photosynthesis it creates the organic molecules which are the substances and contain the energy which was from sunlight- in form of chemical energy.
-impala consumes this for growth, respiration and life processes.
-the leopard consumes the impala and passes on the same molecules reorganize into leopard form and if the lion eats the leopard it would be reorganized into lion form.
- what passes from each stage in the food chain are the substances or matter (C, H, O, N) and the energy which is in the bonds between the elements. (eg. bond [-] between C-H)