Question

Rhizobium is present in

• A. Soil
• B. Root nodules of legumes
• C. Stem nodules
• D. Tumours of leaf

Answer 1

The correct option is B

Root nodules of legumes

The correct option is B

The explanation for the correct option:

1. Rhizobium is a soil bacteria that aid in nitrogen fixation in leguminous plants.
2. It is present in nodules by attaching themselves to the roots of leguminous plants.
3. These nodules fix nitrogen from the air and convert it to ammonia, which the plant can use for growth and development.

The explanation for the incorrect options:

option A :

Soil is bound by bacteria together and uses their secretions to produce macroaggregates in the soil.

option C:

1. The formation of stem nodules is caused by soil bacteria infecting the stems.
2. Crack entry causes stem nodules to form at the point of adventitious root primordia on the stems.

option D

1. Tumors of the leaf are due to swelling or protrusion of localized leaf tissue, often with a distinctive shape and, unlike any organ of the regular plant, occurs.
2. Leaf tumors are usually caused by an infection or a bug.

Final Answer: Rhizobium is present in root nodules of legumes.