23.4 - carbon cycle

what element makes up all living things

carbon

why is carbon cycle important

as there is only a finite supply of carbon on the planet it must be recycled so there is enough for these biological molecules e.g. proteins, lipids, carbohydrates to be formed

what are decomposers

saprophytic organisms e.g. fungi feed on dead organic matter by extracellular digestion

» secret enzymes onto dead organic matter e.g. cellulose into small organic molecules e.g. glucose which the microorganism reabsorbs

why do decomposers perform extracellular digestion

dead organic matter is large and insoluble so cannot pass through fungal cell membrane so extracellular digestion breaks down into small soluble molecules

what does decomposer do with the soluble organic molecules

as fungus digests these soluble organic molecules for its own growth and respiration, excess is released as inorganic ions back into the soil e.g. ammonium ions

what are detritivores

e.g. maggots or lice feed on dead organic matter by internal digestion which increases SA of food = speeds up decomposition

what does the carbon cycle demonstrate

the movement of carbon between biotic and abiotic components

outline carbon cycle

outline the key processes involved in carbon cycle

respiration - organisms use oxygen and carbohydrates to release energy, releasing CO2 back into the atmosphere

photosynthesis - producers absorb CO2 from atmosphere and convert into organic molecules increasing biomass

consumption - carbon transferred through food chains as organisms consume other organisms with carbon trapped in its biomass

decomposition - dead organic matter plants/ animals broken down by detritivores which release CO2 as they respire

fossil fuels - carbon in dead organic matter plants/ animals that doesnt decompose over years transforms into fossil fuels e.g. coal, oil

combustion - fossil fuels are harvested and used e.g. fuel for combustion engines like cars releasing CO2 into atmosphere