Ecology: Cycles within ecoystems

Question 1

Ways carbon is released into the atmosphere

Answer 1

Fossil fuels are burnt (combustion)
Carbon released during respiration of plants, animals and decomposers
Carbon Dioxide in decaying matter and waste, broken down by decomposers

Question 2

Ways carbon is taken out of the atmosphere

Answer 2

Plants take in CO2 for photosynthesis
Fossilisation of dead plants and animals - Fossil fuels (coal and oil)

Question 3

Simple Carbon Cycle:

Answer 3

Carbon is taken out of atmosphere by photosynthesis
It is passed on to animals and decomposers by feeding
It is returned by respiration; in plants, in animals and in decomposing microorganisms
It is also returned by combustion of fossil fuels

Question 4

Nitrogen fixing bacteria:

Answer 4

‘Free living’ in soil, and in root nodules of certain plants (plants that have these = legume
Take N2 gas and change it into nitrates
In return, the plants provide bacteria with organic nutrients

Question 5

Lightning Fixation:

Answer 5

Lighting provides enough energy for N2 gas to react with oxygen, formintg nitrous oxides (which dissolve in rainwater and leech into soil)

Question 6

Nitrifying Bacteria:

Answer 6

Convert Ammonia into nitrite, then nitrate (in the soil)

Question 7

Denitrifying Bacteria:

Answer 7

Break down Ammonia in soil to form N2 gas

Question 8

Assimilation:

Answer 8

Animals eat plants, taking in on their nitrogen compounds usually in the form of protein

Question 9

Death and excretion:

Answer 9

In animals some nitrogen is excreted in urine
All living organisms die, so the nitrogen compounds are recycled

Question 10

Decomposition:

Answer 10

Dead organisms are broken down by composers (including bacteria living in the soil)
Turns N2 gas in protein into Ammonium

Question 11

Absorption by the roots:

Answer 11

Nitrates can be absorbed into the plant via the roots through active transport
The plant can use these to make protein as they are more reactive than oxygen