Nutrient cycling Flashcards
What do organisms need nitrogen for?
Living organisms need Nitrogen for amino acids, proteins, nucleic acids and other important organic molecules.
Plants and animals are unable to use nitrogen gas.
Nitrogen gas must be converted to nitrates before it can be used by plants.
What are the 4 types of bacteria?
Decomposing bacteria
Nitrifying bacteria
Denitrifying bacteria
Nitrogen fixing bacteria
What does Decomposing bacteria do?
along with fungi decompose dead plants and animals, faeces, and urine into simpler molecules.
What is the process on which decomposing bacteria does?
Ammonification
Complex molecules like proteins, amino acids and urea are broken down and nitrogen is released into the environment as ammonium (NH4+).
What does Nitrifying bacteria do?
convert the NH4+ into nitrates (NO3-), under aerobic conditions.
Nitrates can be used by plants to make protein and nucleic acids.
Describe the process of nitrification (2)
Nitrosomonas bacteria oxidise ammonium ions (NH4+) to nitrite (NO2-).
Nitrobacter oxidise nitrite (NO2-) to nitrate (NO3-).
This is nitrification.
What does Nitrogen fixing bacteria do?
Nitrogen fixing bacteria take nitrogen gas out of the air and convert it ammonia (NH3).
Describe the process for nitrogen fixing bacteria (4)
- Rhizobium bacteria are found in the roots of legumes such as peas, beans and clover.
- The roots swell to form root nodules.
- The bacterium form a mutualistic relationship.
- The bacterium fixes nitrogen and it gains carbohydrate from the host plant.
What does denitrifying bacteria do?
convert nitrates and ammonium ions back to nitrogen gas.
This occurs in the absence of oxygen. For example in waterlogged soil.
Describe the process of the nitrogen cycle? (5)
- Atmospheric Nitrogen (N2) is converted to nitrates, for plants to be able to obtain it and use it,
- On which then can be incorporated into animals
- When animals and plants die, decomposing bacteria breaks this down NH4+
- Nitrifying bacteria then converts NH4+ into NO2- , then oxidising it into NO3-
- Denitrifying bacteria converts NO3- and NH4+ back to N2 (nitrogen gas) and gas returns back to the atmosphere
What is the greenhouse effect?
Natural process that warms the Earth’s surface. When the sun’s energy reaches the Earth’s atmosphere, some of it is reflected back to space and the rest is absorbed and re-radiated by greenhouse gases which ultimately maintains the temperature of the Earth’s surface.
What is detritus?
fragments of dead and decaying matter
What are detritovores?
Detritivores are animals that feed on detritus such as earthworms, woodlice and maggots.
They break up the detritus into small fragments that the decomposers can then act upon.
Detritivores enable the process of decomposition to be speeded up.
Describe the process of the carbon cycle. (7)
- Energy enters ecosystems as sunlight trapped by producers.
It is then transferred up various trophic levels eventually being released as heat. - Plants obtain inorganic nutrients from the soil and water. Consumers take this energy by consuming plants.
- Plants and animals then decay and turn into humus, where detritivores break up these into smaller fragments
- On which decomposers then release enzymes to break these down, and release the nutrients into the soil or water
- which this humus can be converted into fossil fuels, on which factory use this, which in turn releases fossil fuels and carbon back into the atmosphere.
- Cellular respiration and photosynthesis from plants and animal respiration also occur.
- Atmospheric CO2, nutrients are later released back into the environment for reuse.
How is there a fixed amount of nutrients on earth?
Unlike energy, these nutrients are later released back into the environment for reuse.
(There is a fixed amount of nutrients on Earth and they constantly move from the air, water and soil into living organisms and back again.
Nutrients are cycled between the biotic and abiotic environments.)
