Question

Nif gene occurs in
A) Rhizobium
B) Penicillium
C) Aspergillus
D) Streptococcus

Answer 1

Hint: The genes which encode enzymes involved in nitrogen fixation are known as nif genes. They are found in both symbiotic and free-living nitrogen fixing bacteria.

Complete answer:
The process by which atmospheric nitrogen is converted into ammonia is known as nitrogen fixation.
Nitrogen can be fixed by the following ways,
Nitrogen fixation by lightning
Symbiotic nitrogen fixation

Option A: Nif genes are found only in nitrogen fixing bacteria found associated with plants. Rhizobium is a nitrogen fixing bacteria which is found in the roots of leguminous plants. Therefore, this is the correct option.
Option B: Penicillium is a fungus that is involved in food spoilage and is also used in production of antibiotics, but it has no role in nitrogen fixation. Therefore, this is the incorrect option.
Option C: Aspergillus is a fungus and is used for biotransformations and waste management but it has no role in nitrogen fixation. Therefore, this is the incorrect option.
Option D: Streptococcus is a genus of bacteria which can cause pneumonia and are also used in milk, and dairy production but it has no role in nitrogen fixation. Therefore, this is the incorrect option.

Thus, the correct option is A) Rhizobium.

Note:Rhizobium is a genus of bacteria which is found in the root nodules of leguminous plants. They help in nitrogen fixation by taking up the atmospheric nitrogen and converting it to ammonia, so that the plant can take it up.