Write the steps of the nitrogen cycle
Nitrogen in the air gets converted to nitrates by nitrogen fixing bacteria
These nitrates are used by plants which are than eaten by animals which then die and are decomposed
This releases ammonia
Ammonia is then converted into nitrates again by nitrifying bacteria
This is again used by plants and then given to animals, et cetera
Some of the nitrates are converted back into nitrogen gas by denitrifying bacteria
What does nitrifying bacteria do?
Convert ammonium ions into nitrates
What does nitrogen fixing bacteria do?
Convert nitrogen gas to nitrates
What does denitrifying bacteria do?
Converts nitrates to nitrogen
What do decomposers do?
They decompose proteins and urea and turn them into ammonia which goes on to form ammonium ions
What are the main factors that affects the rate of decomposition?
Oxygen availability
Temperature
Water content
How does oxygen availability affect the rate of decomposition
Many decomposers need oxygen for aerobic respiration so the rate of decomposition increases when there is more oxygen available
When there is low oxygen, the rate of decomposition is slower.
This is because even though some decomposers can respire anaerobically this transfers less energy.
So the decomposers work more slowly than if there was more oxygen available
How does temperature affect the rate of decomposition
Most decomposers work best in warm conditions
This is because decomposers contain enzymes which digest the dead waste or material
The rate of enzyme-controlled reactions varies with the temperature as a lower temperature is the rate of reaction is slower and may even stop but in hot temperature is the enzymes denature and the reaction also stops
How does water content affect decomposition?
Decomposers need water to survive so the rate of decomposition increases in moist conditions
However, waterlogged soils don’t contain much oxygen to the rate decreases if there’s too much water
What are abiotic and biotic factors
Abiotic - non living factors that affect ecosystem
Biotic - living factors that affect ecosystems
What is some examples of abiotic factors?
light intensity - less = less photosynthesis = less food
Temperature - affect enzyme activity
Soil pH - poor minerals in soil eg nitrates reduce plant growth
Water availability - more competition, wilting, dehydration
Oxygen availability - respiration
CO2 availability - photosynthesis, plants don’t produce enough sugars, less growth
What is example of biotic factors?
Competition - competition for food or territory
Predation - reduces prey population
Disease - kills large number kf a population
Food availability - less food = more competition
Mutualism - helps reproduction
How did decomposers break things down?
They secretes enzymes onto the dead material or waste
The enzymes break large insoluble molecules into smaller soluble molecules
The small molecules dissolve in surrounding water
The dissolve soluble molecules diffuse across the decompose a semipermeable membrane into the cell
These molecules are used for respiration
What are the detritivores
Detritivores are organisms that directly eats dead material
They used to physically breakdown dead plants and animals into small pieces with a higher surface area
They are important to the composition because without them the waste would be too big for the decomposers to breakdown so by breaking down the waste into even smaller pieces to try to help decomposers decompose properly
What is the definition of an individual?
A single organism
What is the definition of a population?
All of the organisms of one species in a habitat
What is the definition of a community?
All of the organisms, even if they are different species living in a habitat
What is the definition of an ecosystem?
A community of organisms along with all of the abiotic conditions
What is parasitism?
When a parasite lives off of another organism and takes what it needs and harms that organism in doing so
What is mutualism?
When one organism lives on another and both are benefited and neither are harmed
What do the arrows in food chains show?
They showed the direction of energy transfer
Why is biomass lost between each trophic level?
Some energy is used to make food by producers,
Some energy is used during respiration by both animals and plants
Biomass can also be lost through digestion and excretion
Why do most food chains have no more than five tropic levels?
There’s not enough biomass left to support the organism after five levels
abiotic factors affecting communities
Temperature
Moisture levels
Soil pH
Light intensity
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Cell Level Systems35
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What Happes In Cells27
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Respiration32
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Photsynthesis16
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Circulatory System28
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Active Transport And Osmosis19
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Transport In Plants31
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Cell Cycle + Mitosis13
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The Nervous System33
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The Endocrine Sustem34
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The Menstrual Cycle34
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Plant Hormones18
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Maimting Internal Environemtns43
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The Kidney10
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Supplysing The Cells17
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Past Paper Q23
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Inheritance50
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The Eye + Brain37
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Mitosis13
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History Of Genetics7
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Ecosystems26
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Evoltion24
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Feeding The Human Race26
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Infection And Disease41
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The Immune System27
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B6.1 Ecosystems31
