Tag: zoology

Rhizobium and Cynobacteria are involved in nitrogen fixation. There are many more bacteria like Nitrobacter, Nitrosomanas etc involve in maintaining the balance of nitrogen gas in the atmosphere.

Rhizobium is a bacterium found in the root nodules of leguminous plants. It induces the formation of special structures called nodules inside which it fixes atmospheric nitrogen. It does this with the help of nitrogenase enzyme that converts of nitrogen to ammonium that is an important factor required for plant growth. In turn, the bacterium receives shelter from the plant. Thus the correct answer is option A.

The second step (oxidation of nitrite into nitrate) is done mainly by bacteria of the genus Nitrosomonas and Nitrobacter.

Oxidation of Ammonia to nitrite is performed by two groups of bacteria. Nitrosomonas and Nitrosocossus are examples of bacterias which perform the oxidation of ammonia to nitrite.

Anaerobic bacteria do not need oxygen. This is because they don't  use oxygen in any of their processes. Thus bacteria are poisoned by oxygen.

Nitrification is a process of conversion of ammonium salts to nitrites and nitrites to nitrates. The bacteria that carry out this process are called as nitrifying bacteria. Nitrosomonas, Nitrosospira, Nitrosococcus convert ammonia into nitrites. Nitrobacter, Nitrospina, Nitrococcus convert nitrites into nitrates.

Atmospheric carbon dioxide is used by plants to produced food. Due to industrialization, large amount of carbon dioxide is released in the atmosphere. This CO$ _2$ provides nutrient source to certain plants. However, excess amount of CO$ _2$ inhibits growth in plants. It inhibits nitrate assimilation in certain plants. It basically inhibits absorption of nitrogen.

Nitrification is a process of conversion of ammonium ions to nitrites and nitrites to nitrates. The bacteria that carry out this process are called as nitrifying bacteria. Nitrosomonas, Nitrosospira, Nitrosococcus convert ammonia into nitrites. Nitrobacter, Nitrospina, Nitrococcus convert nitrites into nitrates.

Atmospheric nitrogen is not available to plants. There are certain nitrogen fixing bacteria which converts atmospheric nitrogen into ammonium compounds and make it available to the plants. Examples include Azotobacter, Frankia, Rhizobium, Azospirillum. Out of these, Azospirillum is widely used as nitrogen fixer organism in paddy fields. It is used as biofertilizer in rice fields. It promotes the plant growth.

There are two steps in nitrification process by which ammonia is converted into nitrite and nitrite into nitrate. The bacteria that convert ammonia to nitrites include Nitrosomonas, Nitrosospira and the bacteria that convert nitrites to nitrates include Nitrobacter, Nitrospina.