Ecology
Food chains
(1)
(2)
(3)
(4)
(5)
Producer that makes its own food - usually a green plant or algae that can photosynthesise
Producers are eaten by animals called primary consumers
Primary consumers are eaten by secondary consumers
Secondary consumers are eaten by tertiary consumers
An apex predator is at the top of the food chain
Carbon cycle
Carbon is present in all living organisms
When organisms die, the carbon is recycled so it is used by future generations
Water cycle
How water moves between different locations - rivers, oceans, atmosphere
Water has to change state for this to occur
Process:
Carbon is removed from the atmosphere by producers who use it in photosynthesis
By consuming plant matter, animals obtain carbon compound
carbon is returned into the atmosphere due to the respiration that happens in plant and animal cells
When animals and plants die, decomposers return the carbon back to the atmosphere via decay
Combustion of fossil fuels is another source of carbon entry
Process:
Water evaporates from the earth's surface
Once in the atmosphere the water vaper cools and condenses into rain or snow which returns to the Earth's surface
Rain or snow will flow off land or travel through the earth as ground water
Plants take water through their roots
Decay
Rate of decay
High oxygen availability is best
High temperature is best
High moisture availability is usually best
Biogas generators
Anaerobic decay happens when oxygen supply is not enough and results in biogas production - mainly methane
Biogas generators produce methane gas which is used as a fuel
Temperatures must be maintained at a suitable level and oxygen must stay out
Large scale vs small scale
Large
Small
Used by farms and household with inputs being excretion from humans and animals as well as farm and garden waste
Take waste from sewage works or sugar factories
Higher temperatures mean decomposers become more active and rate of decay increases
At extremely high temperatures the decomposers are killed and decomposition stops
Decomposers need oxygen to survive and without it there is little or no decomposition
Oxygen is needed for decomposers to respire to enable them to grow and multiply
Why we seal food in bags
Why we put food in the fridge
With little or no water there is less decomposition because decomposers don't survive
As water volume increases rate also increases
Many decomposers use enzymes to break down mater and absorb dissolved molecules but without water these wouldn' workt