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Do you guys still remember the carbon cycle in I/GCSE Biology?
Capturing carbon dioxide
- Fixing – Absorbing carbon dioxide from the air and converting it into complex carbon compounds. Plants fix carbon dioxide during photosynthesis
- CO2 molecule taken into leaf – during photosynthesis changed into organic carbon compound = glucose (carbohydrate) = fixing
- Removes carbon from physical environment
- Refer to I/GCSE Biology, Glucose used for respiration = converted to CO2 + released back into air
- Glucose may be changed into complex carbon compounds e.g. carbs, proteins & fats in plant tissue

Carbon compounds in animals
In I/GCSE Biology,
- If plant eaten by animal – plant tissue broken down during digestion
- Some carbon compounds
- absorbed through animals gut + made into carbs, proteins, fats etc. rest = faeces
- converted to glucose for respiration then transformed to CO2 – released into atmosphere
- become part of animals body tissues or excreted in urine – animal eaten = same processes happen in that animal n
- Plant or animal not eaten = die and detritus feeders will feed on dead body
- Detritus feeder = an organism that feeds on detritus (decomposing organic waste)
- Break down complex carbon compounds + use them to make more carbon compounds in their bodies – release carbon as CO2 to air from respiration
- Decomposer organism e.g. fungi + B continue process of decay – do the same as arrow above
The full cycle

- Heat + pressure turns large quantities if organisms e.g. trees into fossil fuels
- Combustion of fossil releases CO2 into air
- When carbon returned, leaf captures it and fixes it in photosynthesis – cycle starts again
- Constant cycling of carbon through carbon compounds in living organisms + CO2 in air = carbon cycle
- Carbon cycle = the way in which carbon atoms circulate between living organisms and the physical environment
- Only nutrients and CO2 continuously cycled – energy is captured by plants then transferred as heat to environment – energy can't be used by living organisms = no energy cycle
- Plants photosynthesise during day, take CO2 from atmosphere. Plants respire all the time releasing CO2 back into atmosphere
That's all~