SB9k-m Flashcards
What is biomass made up of?
Carbon compounds.
How are do carbon compounds become carbon dioxide?
They are broken down in the atmosphere with the help of decomposers.
What is an example of a decomposer?
Fungi.
What are fungi and how do they feed?
As fungi are saprophytes. They use extracellular digestion using enzymes and feed on decaying organisms.
Which processes release CO2 into the atmosphere?
- Respiration
- Decomposition
- Combustion of fossil fuels
Which processes absorb CO2 from the atmosphere?
- Photosynthesis
- Fossilisation
How do we represent the carbon cycle?
Check teacher notes ‘Carbon Cycle’ p19 diagram.
What causes decomposition?
Dentritus feeders and bacteria.
What happens during decomposition?
Carbon compounds are broken down into CO2 which is released back into the atmosphere.
How does fossilisation occur?
When dead plants/animals are buried under many layers of soil, decomposers cannot feed on them so carbon compounds remain locked in them.
How can we release the carbon compounds in fossils?
Combustion.
What percentage of the atmosphere is nitrogen gas?
78%
What is the issue with nitrogen gas?
Plants and animals can only use nitrogen in the form of nitrates.
How can we turn nitrogen gas into nitrates?
- Nitrification
- Lightning
- Using nitrogen fixing bacteria
How can we turn nitrates into nitrogen gas?
- Denitrification
What do plants and animals need nitrogen in the form of nitrates for?
- DNA replication
- Growth
- Protein synthesis
How is ammonia converted into nitrates?
With the help of nitrifying bacteria.
How does the nitrification process turn nitrogen gas into nitrates?
Dead plants and animals together with faeces and urine are converted to ammonia. Nitrifying bacteria convert the ammonia to nitrates in the soil.
What are the tiny bags on legume roots called?
Root nodules.
How do nitrogen fixing bacteria turn nitrogen gas into nitrates?
Root nodules contain nitrogen fixing bacteria which turns nitrogen gas into nitrates in the soil. Farmers plant legumes in their field for the soil to have nitrates.
How does the denitrification process turn nitrates into nitrogen gas?
Denitrifying bacteria turn nitrates back into nitrogen gas in waterlogged soils.
How can we represent the nitrogen cycle?
Check teacher notes ‘Nitrogen cycle’ p22 diagram.
What are 3 ways farmers use to increase nitrates in their soils?
- Add manure
- Artificial fertilisers that contain nitrates
- Use crop rotation
What is crop rotation?
The process where farmers keep their soil fertile by planting legumes.
How does the process of crop rotation work?
- Legumes will release nitrates into the soil
- The following year a different crop will be planted and benefit from the nitrates in the soil
- The following year another crop will be planted
- The following year legumes will be planted again
In which environments do decomposers grow best in?
- Warmth
- Moisture
- Plenty of oxygen
How do we preserve food to prevent decomposers from decaying it?
- Reducing temperature (e.g. fridges and freezers)
- Reducing water content by
a. Dehydration
b. Adding salt - Irradiation of packaged foods to kill decomposers
- Reducing oxygen in food packages so nitrogen gas is used instead
- Store foods in oil/vinegar/sugar syrup
How is irradiation done?
By the use of ionising radiation (e.g. gamma rays).
What is compost?
Completely decayed waste garden materials and decaying fruits and vegetables which can be used as a fertiliser. Spreading compost into soil increases soil fertility.
How do we create compost?
Put decaying matter into heap and leave them to decay completely.
What are the conditions needed to create compost?
- Oxygen
- Moisture
- Warmth
How do we calculate the rate of decomposition?
mass lost
Rate of decomposition (g/day) = __________________
number of days
