Nitrogen Cycle Flashcards
Why is nitrogen essential to life?
It makes up nitric acid, a monomer of DNA and RNA.
What sphere are the following compounds in? Nitrogen gas (N2) and nitric oxide and nitrous oxide (NO and N2O)
Atmosphere
How much of the atmosphere does nitrogen gas make up?
70%
What sphere are the following compounds in? Ammonia (NH4), urea/organic nitrogen ((NH2)2CO) and nitrate (NO3)
Biosphere
Which sphere are the following compounds in? Ammonia (NH4) and nitrate (NO3)
Lithosphere and hydrosphere
What is nitric and nitrous oxide (NO and N2O) commonly known as?
Greenhouse gases and smog.
Is nitrogen gas accessible by plants or animals?
Not accessible to MOST living organisms.
Is ammonia accessible by plants or animals?
Yes
Is urea/organic nitrogen accessible by plants or animals?
Yes
Is nitrate accessible by plants or animals?
Yes
Is nitric and nitrous oxide accessible by plants or animals?
No
What is the process of nitrogen fixation in the nitrogen cycle?
Bacteria called nitrogen fixing bacteria can take nitrogen gas from the atmosphere and convert it to ammonia. The bacteria live in the soil or in a symbiotic relationship with the root nodules of legumes (peas, lupin etc). In the hydrosphere cyanobacteria (blue-green algae) can fix nitrogen. These bacteria contain enzymes that can break the bonds between the two nitrogen atoms so they can bond with other elements. Lightning also has enough energy to break apart these bonds so is able to fix nitrogen.
What nitrogen compounds are involved in nitrogen fixation?
Nitrogen gas and ammonia.
What organisms are involved in the process of nitrogen fixation?
Nitrogen fixing bacteria
What is the process of nitrogen uptake in the nitrogen cycle?
Plants are able to uptake ammonia.
What organisms are involved in nitrogen uptake?
Plants
What nitrogen compounds are involved in nitrogen uptake?
Ammonia
What is the process of feeding in the nitrogen cycle?
Animals eat the plants that have uptake ammonia, the animals convert ammonia to urea which is excreted in urine.
What organisms are involved in feeding?
Plants and animals
What nitrogen compounds are involved in feeding.
Ammonia and organic nitrogen.
What is the process of decomposition in the nitrogen cycle?
When organisms die, decomposers consume the organic matter and lead to the process of decomposition. During this process, the nitrogen contained within the dead organism is converted to ammonium (ammonification).
What organisms are involved in decomposition?
Bacteria and fungi
What nitrogen compounds are involved in decomposition?
Organic nitrogen and ammonia
What is the process of nitrification in the nitrogen cycle?
Nitrifying bacteria are able to convert ammonia in the soil to nitrate in the presences of oxygen.
What organisms are involved in nitrification?
Nitrifying bacteria
What nitrogen compounds are involved in nitrification?
Ammonia and nitrates
What is the process of denitrification in the nitrogen cycle?
Denitrifying bacteria convert nitrates back to atmospheric nitrogen in anoxic (no oxygen) conditions such as in waterlogged soils.
What organisms are involved in denitrification?
Denitrifying bacteria.
What nitrogen compounds are involved in denitrification?
Nitrates and atmospheric nitrogen.
Draw an annotated diagram of the nitrogen cycle. (6 marks)
Half a mark for each correct process described.
Full marks if all processes above are included and described.
What are some of the reasons that organisms need nitrogen?
- Proteins- makes up nucleotides
- Nucleic acids
What do the bacteria that live in legumes do?
Break down the nitrogen and convert it to ammonia.
What can over fertilising crops do to the nitrogen cycle?
Excess nitrogen from the fertilisation of plants can run into waterways, this causes an increase in algae. When algae dies it can cause eutrophication to occur. The dissolved oxygen used in the decomposition of the dead algae can be used up in the water, leaving other organisms with none.
