Question

The Rhizobium bacteria lines inside the root nodules of--
A. Pea plant
B. Beans
C. Peanuts
D. All of the above.

Answer 1

Hint:Rhizobium bacteria is involved in fixation of nitrogen. The nitrogen cycle is an important part of living organisms, it helps in maintaining nitrogen balance in the environment. Nitrogen is found in proteins, chlorophyll, nucleic acids, and vitamins.

Complete answer:
Rhizobium bacteria have a symbiotic relationship with plants like legumes. Symbiotic relation is between two species with which at least one of them gets the benefit of others.
Rhizobium fixes nitrogen from the air into ammonia. This ammonia acts as a natural fertilizer for the plants.
Nitrogen can get fixed from the atmosphere as well but it is constant due to the nitrogen cycle.
Rod-shaped, gram-negative rhizobium has a common association on roots especially on small outgrowth on the roots known as nodules.
Pea plant, beans, peanuts are all legumes.

The correct answer is option D) All of the above.

Note: Plants and animals cannot take nitrogen directly hence this nitrogen is fixed from the atmosphere into simple compounds of nitrogen by certain bacteria and blue-green algae.
These simple compounds are utilized by plants from soil and further these plants are eaten by animals. These animals get proteins and nitrogen compounds.
When these animals and plants die, their nitrogenous waste is converted into nitrogenous compounds by bacteria and fungi. Some part of this compound is utilized by plants as nutrients and some part is converted into gas by certain bacteria and fungi. This goes back into the atmosphere through a gas.
This is the nitrogen cycle.
Therefore as mentioned earlier the percentage of nitrogen remains constant.