Question

Microorganism forming symbiotic association with plants and helps them in their nutrition is:

• A. Azotobacter
• B. Azospirillum
• C. Klebsiella
• D. Glomus

Hint:

NCERT Point: Glomus \(\rightarrow\) Mycorrhiza Mycorrhiza \(\rightarrow\) Better phosphorus absorption and improved plant growth.

Answer 1

The Correct Option is D

Concept: Many microorganisms form beneficial associations with plants and help them absorb nutrients from the soil. Such relationships are called symbiotic associations. One of the most important examples is Mycorrhiza, a symbiotic association between fungi and plant roots. The fungal partner increases the surface area available for absorption of water and minerals, especially phosphorus.

Step 1: Understand the meaning of symbiotic association.
Symbiosis refers to a close association between two different organisms in which both organisms benefit. In plants, some microorganisms live in association with roots and improve nutrient uptake.

Step 2: Study the role of Glomus.
Glomus is a fungus that forms mycorrhizal associations with roots of higher plants. Benefits provided by Glomus include:
• Better absorption of phosphorus
• Better absorption of water
• Increased resistance to root pathogens
• Increased tolerance to drought and salinity
• Overall improvement in plant growth

Step 3: Examine the remaining options.
Azotobacter is a free-living nitrogen-fixing bacterium. Azospirillum is an associative nitrogen fixer. Klebsiella can fix nitrogen but is not the mycorrhizal symbiont referred to in NCERT. Only Glomus forms a true mycorrhizal symbiotic association with plant roots.

Step 4: Choose the correct answer.
Therefore, \[ \boxed{\textit{Glomus}} \] is the correct answer.