Question

1.Fill in the blanks -
a) Algae such as ___ and ___ fix nitrogen using oxygen from the atmosphere..
b)___ temperature inhibits the growth of microbes..
2.Write One word for:
a) An anti biotic produced from bacteria and fungi ___
3.Explain how the concentration of nitrogen remains constant in the atmosphere? (Nitrogen cycle)

Answer 1

1.a) blue green algae and nostoc
b) 30° to 50°

2.a) penicillin

3.The percentage of nitrogen in atmosphere is kept constant through nitrogen cycle.The sequence in which nitrogen in the atmosphere is passed into the soil and lifeforms, and then released back into the atmosphere, is called the nitrogen cycle.

a) Nitrogen fixation: The process of conversion of atmospheric nitrogen into nitrogenous compounds and making it available for plants is called as nitrogen fixation. Nitrogen fixation can happen by biological processes or physical processes. Nitrogen is introduced to the soil by fertilisers or animal and plant residues.

b) Ammonification: The process of production of ammonia from organic compounds is called ammonification. Ammonification is the process carried out by a variety of microorganisms that breakdown protein, amino acids, and othernitrogen-containing compounds of dead and waste organic matter to form ammonia.

c) Nitrification: It is the process by which ammonia is converted to nitrites (NO2-) and then to nitrates (NO3-). This process naturally occurs in the environment, whereit is carried out by specialised bacteria. Nitrosomonas and nitrobacter are the bacteria which bring about nitrification.


d) Denitrification: It is the biological conversion of nitrate to nitrogen gas, nitricoxide or nitrous oxide. These compounds are gaseous compounds and are not readily available for microbial growth. Therefore, they are typically released into atmosphere. This process is brought about by denitrifying bacteria.

Answer 2

Answer:

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Explanation:

) Algae such as ___ and ___ fix nitrogen using oxygen from the atmosphere..

b)___ temperature inhibits the growth of microbes..

2.Write One word for:

a) An anti biotic produced from bacteria and fungi ___

3.Explain how the concentration of nitrogen remains constant in the atmosphere? (Nitrogen cycle)