Consider the following statements regarding the relationship between legumes and Rhizobium: 1. It is an example of a symbiotic relationship. 2. The bacteria provide food and shelter to the plant. 3. The plant provides nitrogen to the bacteria. Which of the statements given above is/are correct?

Correct Option The correct option is (a). Explanation The relationship between leguminous plants (such as peas, beans, and lentils) and Rhizobium bacteria is a classic example of biological nitrogen fixation. This association occurs within specialized structures on the plant roots called nodules. Statement-wise Analysis - Statement 1 is Correct: The association between legumes and Rhizobium is a symbiotic relationship, specifically mutualism, where both organisms benefit from each other. The bacteria reside inside the root nodules of the host plant. - Statement 2 is Incorrect: The roles described are reversed. The plant provides food (organic nutrients derived from photosynthesis) and shelter (root nodules) to the bacteria. The bacteria do not provide food or shelter to the plant; rather, they provide fixed nitrogen. - Statement 3 is Incorrect: The plant does not provide nitrogen to the bacteria. Instead, the Rhizobium bacteria fix atmospheric nitrogen ($N_2$) into ammonia ($NH_3$), a form of nitrogen that the plant can utilize for its growth and development. Key Takeaway: In the legume-Rhizobium symbiosis, the plant acts as the host providing shelter and carbohydrates (energy), while the bacteria act as the nitrogen fixer, converting atmospheric nitrogen into a usable form for the plant.

NCERT Class 7 Science — Chapter 1: Nutrition in plants

mcqmedium

Consider the following statements regarding the relationship between legumes and Rhizobium:

It is an example of a symbiotic relationship.
The bacteria provide food and shelter to the plant.
The plant provides nitrogen to the bacteria.

Which of the statements given above is/are correct?

Official previous-year question

Verified 1 Aug 2026.

Options

A1 only
B2 only
C1 and 3 only
D1, 2 and 3

Did you get this right?

Solution

Correct Option

The correct option is (a).

Explanation

The relationship between leguminous plants (such as peas, beans, and lentils) and Rhizobium bacteria is a classic example of biological nitrogen fixation. This association occurs within specialized structures on the plant roots called nodules.

Statement-wise Analysis

Statement 1 is Correct: The association between legumes and Rhizobium is a symbiotic relationship, specifically mutualism, where both organisms benefit from each other. The bacteria reside inside the root nodules of the host plant.
Statement 2 is Incorrect: The roles described are reversed. The plant provides food (organic nutrients derived from photosynthesis) and shelter (root nodules) to the bacteria. The bacteria do not provide food or shelter to the plant; rather, they provide fixed nitrogen.
Statement 3 is Incorrect: The plant does not provide nitrogen to the bacteria. Instead, the Rhizobium bacteria fix atmospheric nitrogen ($N_2$) into ammonia ($NH_3$), a form of nitrogen that the plant can utilize for its growth and development.

Key Takeaway: In the legume-Rhizobium symbiosis, the plant acts as the host providing shelter and carbohydrates (energy), while the bacteria act as the nitrogen fixer, converting atmospheric nitrogen into a usable form for the plant.

Your note

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With reference to saprotrophic nutrition, consider the following statements: 1. It is a mode of nutrition where organisms take in nutrients from dead and decaying matter. 2. Fungi ingest dead matter directly without secreting digestive juices. 3. All fungi are harmful and cause spoilage of food and diseases. Which of the statements given above is/are correct?

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Correct Option

The correct option is (a).

Explanation

Statement-wise Analysis

Statement 1 is Correct: The association between legumes and Rhizobium is a symbiotic relationship, specifically mutualism, where both organisms benefit from each other. The bacteria reside inside the root nodules of the host plant.
Statement 2 is Incorrect: The roles described are reversed. The plant provides food (organic nutrients derived from photosynthesis) and shelter (root nodules) to the bacteria. The bacteria do not provide food or shelter to the plant; rather, they provide fixed nitrogen.
Statement 3 is Incorrect: The plant does not provide nitrogen to the bacteria. Instead, the Rhizobium bacteria fix atmospheric nitrogen ($N_2$) into ammonia ($NH_3$), a form of nitrogen that the plant can utilize for its growth and development.