NITROGEN CYCLE

Question 1

cannot be directly utilised by living organisms and has to be converted to other forms.

Answer 1

Nitrogen

Question 2

is a biogeochemical
process which transforms the inert
nitrogen present in the atmosphere to a
more usable form for living organisms

Answer 2

Nitrogen Cycle

Question 3

• is the initial step of the nitrogen cycle
• Atmospheric nitrogen (N2) which is primarily available in an inert form, is converted into the usable form - ammonia (NH3)
• the inert form of nitrogen gas is deposited into soils from the atmosphere and surface waters, mainly through precipitation.
• completed by symbiotic bacteria, which are known as Diazotrophs

Answer 3

Nitrogen Fixation Process

Question 4

Types of Nitrogen Fixation

A natural phenomenon where the
energy of lightning breaks the nitrogen into nitrogen oxides, which are then used by plants.

Answer 4

Atmospheric fixation

Question 5

Types of Nitrogen Fixation

-a man-made alternative that aids in nitrogen fixation by the use of ammonia.
-Ammonia is produced by the direct
combination of nitrogen and hydrogen.
-Later, it is converted into various fertilisers such as urea.

Answer 5

Industrial nitrogen fixation

Question 6

Types of Nitrogen Fixation

nitrogen is not used directly from the air by plants and animals.

Answer 6

Biological nitrogen fixation

Question 7

-When plants or animals die, the nitrogen
present in the organic matter is released back into the soil
-The decomposers, namely bacteria
or fungi present in the soil, convert the
organic matter back into ammonium.
-This process of decomposition produces ammonia, which is further used for other biological processes.

Answer 7

Ammonification

Question 8

Atmospheric nitrogen is converted to nitrates directly by lightning and assimilated by plants

Answer 8

Atmospheric fixation

Question 9

Decomposers break down proteins and amino acids of dead and decaying organic matters and waste product

Answer 9

Ammonification

Question 10

-the ammonia is converted into nitrate by the presence of bacteria in the soil.
-Nitrites are formed by the
oxidation of ammonia with the help of Nitrosomonas bacteria
species.
-the produced nitrites are converted into nitrates by Nitrobacter.
-This conversion is very important as ammonia gas is toxic for plants

Answer 10

Nitrification

Question 11

Primary producers- plants take in the nitrogen compounds from the soil with the help of their roots, which are available in
the form of ammonia, nitrite ions, nitrate ions or ammonium ions and are used in the formation of the plant and animal proteins. This way, it enters the food web when the primary consumers eat the plants.

Answer 11

Assimilation

Question 12

is the process in which the nitrogen compounds make their way back into the atmosphere by converting nitrate (NO3-) into gaseous nitrogen (N).

Answer 12

Denitrification