Consider the following statements about Rhizobium bacteria: 1. They are found in the nodules of roots of leguminous plants. 2. They help in fixing atmospheric oxygen into the soil. 3. They deplete the soil of its nitrogen content. Which of the statements given above is/are correct?

The correct option is (a). Explanation The role of symbiotic bacteria in agriculture, specifically focusing on biological nitrogen fixation in plants. - Statement 1 is Correct: Rhizobium bacteria form a symbiotic relationship with leguminous plants (such as peas, beans, and lentils). They inhabit the roots of these plants, leading to the formation of specialized structures known as root nodules, where the bacteria reside. - Statement 2 is Incorrect: Rhizobium helps in fixing atmospheric nitrogen, not oxygen. It converts inert atmospheric nitrogen (N2) into ammonia (NH3), a form that plants can absorb and utilize for growth. The enzyme responsible for this process, nitrogenase, is actually sensitive to oxygen. - Statement 3 is Incorrect: Instead of depleting the soil, Rhizobium enriches the soil with nitrogen. By converting atmospheric nitrogen into soluble compounds, it increases soil fertility, acting as a natural biofertilizer. Key Takeaway: Rhizobium is a symbiotic bacterium found in the root nodules of legumes that fixes atmospheric nitrogen, thereby enhancing soil fertility and supporting plant nutrition.

NCERT Class 8 Science — Chapter 1: Crop production and management

mcqmedium

Consider the following statements about Rhizobium bacteria:

They are found in the nodules of roots of leguminous plants.
They help in fixing atmospheric oxygen into the soil.
They deplete the soil of its nitrogen content.

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

The correct option is (a).

Explanation

The role of symbiotic bacteria in agriculture, specifically focusing on biological nitrogen fixation in plants.

Statement 1 is Correct: Rhizobium bacteria form a symbiotic relationship with leguminous plants (such as peas, beans, and lentils). They inhabit the roots of these plants, leading to the formation of specialized structures known as root nodules, where the bacteria reside.
Statement 2 is Incorrect: Rhizobium helps in fixing atmospheric nitrogen, not oxygen. It converts inert atmospheric nitrogen (N₂) into ammonia (NH₃), a form that plants can absorb and utilize for growth. The enzyme responsible for this process, nitrogenase, is actually sensitive to oxygen.
Statement 3 is Incorrect: Instead of depleting the soil, Rhizobium enriches the soil with nitrogen. By converting atmospheric nitrogen into soluble compounds, it increases soil fertility, acting as a natural biofertilizer.

Key Takeaway: Rhizobium is a symbiotic bacterium found in the root nodules of legumes that fixes atmospheric nitrogen, thereby enhancing soil fertility and supporting plant nutrition.

Your note

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Consider the following statements regarding the preparation of soil: 1. Loosening the soil makes it compact and prevents root penetration. 2. Turning the soil brings nutrient-rich soil to the top for plant utilization. 3. Loosened soil promotes the growth of earthworms and soil microbes. Which of the statements given above is/are correct?

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The correct option is (a).

Explanation

The role of symbiotic bacteria in agriculture, specifically focusing on biological nitrogen fixation in plants.

Statement 1 is Correct: Rhizobium bacteria form a symbiotic relationship with leguminous plants (such as peas, beans, and lentils). They inhabit the roots of these plants, leading to the formation of specialized structures known as root nodules, where the bacteria reside.
Statement 2 is Incorrect: Rhizobium helps in fixing atmospheric nitrogen, not oxygen. It converts inert atmospheric nitrogen (N₂) into ammonia (NH₃), a form that plants can absorb and utilize for growth. The enzyme responsible for this process, nitrogenase, is actually sensitive to oxygen.
Statement 3 is Incorrect: Instead of depleting the soil, Rhizobium enriches the soil with nitrogen. By converting atmospheric nitrogen into soluble compounds, it increases soil fertility, acting as a natural biofertilizer.

Key Takeaway: Rhizobium is a symbiotic bacterium found in the root nodules of legumes that fixes atmospheric nitrogen, thereby enhancing soil fertility and supporting plant nutrition.