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Why is nutrient cycling important?
Nutrients cycling is important because it allows nutrients to be released from tissues so that they become available again for other organisms to use. Without nutrient cycling ecosystems would run out of essential nutrients.
How is carbon taken out of the atmosphere during the carbon cycle?
Carbon is taken out of the atmosphere in the form of carbon dioxide by plants during photosynthesis.
What happens to carbon when a primary consumer eats a plant?
When primary consumers eat a plant the following may happen to the stored carbon:
Carbon compounds in the plant are digested and used to build new carbon compounds which are stored in the animal's tissues
Some of the carbon compounds may be used by the consumer in respiration, releasing carbon dioxide into the atmosphere
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Why is nutrient cycling important?
Nutrients cycling is important because it allows nutrients to be released from tissues so that they become available again for other organisms to use. Without nutrient cycling ecosystems would run out of essential nutrients.
How is carbon taken out of the atmosphere during the carbon cycle?
Carbon is taken out of the atmosphere in the form of carbon dioxide by plants during photosynthesis.
What happens to carbon when a primary consumer eats a plant?
When primary consumers eat a plant the following may happen to the stored carbon:
Carbon compounds in the plant are digested and used to build new carbon compounds which are stored in the animal's tissues
Some of the carbon compounds may be used by the consumer in respiration, releasing carbon dioxide into the atmosphere
How is carbon returned to the atmosphere in the carbon cycle?
Carbon is returned to the atmosphere when it is released as carbon dioxide by the following processes:
Respiration in plants and animals
Respiration of decomposers, e.g. bacteria
Combustion of fossil fuels or other organic matter, e.g. wood
Reversal of the dissolving process by which carbon dioxide dissolves in the oceans
What is the role of combustion in the carbon cycle?
Combustion releases carbon dioxide into the atmosphere. This occurs during the combustion of fossil fuels, or of other organic matter such as wood.
True or False?
Increased use of fossil fuels is contributing to an increase in the carbon dioxide content of the atmosphere.
True.
Fossil fuel use releases carbon dioxide into the atmosphere by the process of combustion. This raises the atmospheric carbon dioxide concentration.
What is the impact of mass deforestation on the carbon cycle?
Mass deforestation (cutting down many trees) affects the carbon cycle as follows:
It reduces the number of trees carrying out photosynthesis so less carbon is removed from the atmosphere
It is often followed by combustion as trees are burned, increasing the addition of carbon to the atmosphere
Why is nitrogen needed by living organisms?
Nitrogen is required by living organisms to make proteins.
True or False?
Plants and animals can absorb nitrogen gas directly from the air.
False.
Neither plants nor animals can absorb nitrogen gas (N2) from the air. N2 needs to be fixed to produce nitrates before nitrogen can be absorbed by plants and passed on to animals.
How is nitrogen gas converted into a usable form during the nitrogen cycle?
Nitrogen gas can be converted into a usable form as follows:
Nitrogen-fixing bacteria convert N2 gas into ammonium compounds, which can then be converted to usable nitrates
Lightning can split the bond between the two N atoms, turning them into nitrous oxides that dissolve in rainwater and leach into the soil
What is the role of nitrogen-fixing bacteria in the nitrogen cycle?
Nitrogen-fixing bacteria are bacteria that convert nitrogen gas into ammonium compounds, which can then be converted to usable nitrates; this is known as nitrogen fixation.
In what form do plants absorb nitrogen from the soil?
Plants absorb nitrogen from the soil in the form of nitrates.
How do animals obtain the nitrogen they need?
Animals get the nitrogen they need from plant proteins or from the tissues of other animals when they eat.
Give an example of a group of organisms that can act as decomposers.
Examples of organism groups that can act as decomposers include:
Bacteria
Fungi
There are other organisms that consume dead material, e.g. earthworms and woodlice, but these organisms do not release nutrients into the environment in the same way as decomposers.
True or False?
The action of decomposers returns nitrogen to the soil in the nitrogen cycle.
True.
Decomposers break down proteins in the dead and waste material, allowing nitrogen to return to the soil.
What is the role of nitrifying bacteria in the nitrogen cycle?
Nitrifying bacteria convert ammonium compounds to nitrites and then to nitrates, which can then be absorbed by plants.
True or False?
Denitrifying bacteria increase the availability of soil nutrients.
False.
Denitrifying bacteria take nitrates out of the soil and convert them back into nitrogen gas, reducing soil fertility and plant growth.