Nitrogen And The Nitrogen Cycle (T4)

Question 1

Why is nitrogen important?

Answer 1

It is a vital component of biological compounds

Question 2

Like carbon, nitrogen is also a vital component of many biological compounds. Describe the key processes of the nitrogen cycle…

Answer 2

• nutrition and assimilation allows nitrogen atoms to pass along food chains
• decomposition by microorganisms called decomposers produces ammonia (which contains nitrogen) from compounds such as proteins, DNA and vitamins
• ammonia is firstly converted to nitrite by oxidation, then to nitrate by specific bacteria called nitrifying bacteria; this process us called nitrification
• the roots of plants can absorb nitrates, which are combined with carbohydrates from photosynthesis to form amino acids which then form proteins as well as other compounds which also contain nitrogen

Question 3

What is ‘nitrification’?

Answer 3

Once produced by decomposers, ammonia is converted to nitrite by oxidation, then to nitrate by specific bacteria called nitrifying bacteria. This process is called nitrification.

Question 4

A wide range of bacteria are involved in different parts of the nitrogen cycle. What are the key bacteria and processes involved?

Answer 4

Denitrifying bacteria use nitrates as an energy source and convert them into nitrogen gas. The process of denitrification reduces the amount of nitrates in the soil.

Nitrogen fixing bacteria in soil convert nitrogen gas into ammonia. The nitrogen is then used by the bacteria to form amino acids and proteins. When these bacteria die their proteins break down releasing the ammonia back into the environment.

Nitrogen fixing bacteria also live in the root nodules of plants. These bacteria also form ammonia, but the ammonia is converted by the plant into amino acids and other organic compounds which contain nitrogen. Again, once the plants die their composition returns the nitrogen back to the soil in the form of ammonia.

Lightning converts nitrogen gas in the air into oxides of nitrogen which then dissolve in rainwater and enter the soil, where they are converted into nitrates by nitrifying bacteria.

Question 5

How much nitrogen is in the air?

Answer 5

About 78%

Question 6

What are nitrogen fixing bacteria and what do they do?

Answer 6

Nitrogen fixing bacteria in soil convert nitrogen gas into ammonia. The nitrogen is then used by the bacteria to form amino acids and proteins. When these bacteria die their proteins break down releasing the ammonia back into the environment.

Nitrogen fixing bacteria also live in the root nodules of plants. These bacteria also form ammonia, but the ammonia is converted by the plant into amino acids and other organic compounds which contain nitrogen. Again, once the plants die their composition returns the nitrogen back to the soil in the form of ammonia.

Question 7

What do nitrifying bacteria do?

Answer 7

Denitrifying bacteria use nitrates as an energy source and convert them into nitrogen gas. The process of denitrification reduces the amount of nitrates in the soil.

Question 8

What role to decomposers play in the nitrogen cycle?

Answer 8

Decomposition by microorganisms called decomposers produces ammonia (which contains nitrogen) from compounds such as proteins, DNA and vitamins.