With reference to nutrient cycling in a forest, consider the following statements: 1. Nutrients are cycled back into the soil through decomposition. 2. Humus prevents nutrients from being released into the soil. 3. Roots of living plants absorb nutrients released by decomposers. Which of the statements given above is/are correct?

The correct option is (c). Explanation Nutrient cycling involves the movement and exchange of organic and inorganic matter within an ecosystem. In forest ecosystems, decomposition is the primary mechanism that converts dead organic matter (detritus) into inorganic substances, ensuring the continuity of nutrient availability for producers. Statement-wise Analysis: - Statement 1 is Correct: Decomposition is the process by which decomposers, such as bacteria and fungi, break down complex organic matter from dead plants and animals. This process converts organic compounds into simpler inorganic substances (nutrients), which are cycled back into the soil. - Statement 2 is Incorrect: Humus is a dark, amorphous substance formed during decomposition that is highly resistant to microbial action. While it decomposes very slowly, it serves as a reservoir of nutrients rather than preventing their release. Through a process called mineralization, humus is further degraded by microbes to slowly release inorganic nutrients into the soil, making them available to plants. - Statement 3 is Correct: Once decomposers and mineralization processes release inorganic nutrients (such as nitrogen, phosphorus, and potassium) into the soil solution, these nutrients are absorbed by the roots of living plants. The plants use these nutrients for growth and metabolism, thereby re-entering the food chain. Key Takeaway: The nutrient cycle relies on decomposition to convert detritus into humus and inorganic minerals. Humus acts as a slow-release nutrient bank, and plant roots absorb the mineralized nutrients to sustain the ecosystem's productivity.

NCERT Class 7 Environment & Ecology — Chapter 1: Forests: our lifeline

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With reference to nutrient cycling in a forest, consider the following statements:

Nutrients are cycled back into the soil through decomposition.
Humus prevents nutrients from being released into the soil.
Roots of living plants absorb nutrients released by decomposers.

Which of the statements given above is/are correct?

Official previous-year question

Verified 1 Aug 2026.

Options

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

Did you get this right?

Solution

The correct option is (c).

Explanation

Nutrient cycling involves the movement and exchange of organic and inorganic matter within an ecosystem. In forest ecosystems, decomposition is the primary mechanism that converts dead organic matter (detritus) into inorganic substances, ensuring the continuity of nutrient availability for producers.

Statement-wise Analysis:

Statement 1 is Correct: Decomposition is the process by which decomposers, such as bacteria and fungi, break down complex organic matter from dead plants and animals. This process converts organic compounds into simpler inorganic substances (nutrients), which are cycled back into the soil.
Statement 2 is Incorrect: Humus is a dark, amorphous substance formed during decomposition that is highly resistant to microbial action. While it decomposes very slowly, it serves as a reservoir of nutrients rather than preventing their release. Through a process called mineralization, humus is further degraded by microbes to slowly release inorganic nutrients into the soil, making them available to plants.
Statement 3 is Correct: Once decomposers and mineralization processes release inorganic nutrients (such as nitrogen, phosphorus, and potassium) into the soil solution, these nutrients are absorbed by the roots of living plants. The plants use these nutrients for growth and metabolism, thereby re-entering the food chain.

Key Takeaway:
The nutrient cycle relies on decomposition to convert detritus into humus and inorganic minerals. Humus acts as a slow-release nutrient bank, and plant roots absorb the mineralized nutrients to sustain the ecosystem's productivity.

Your note

More from Chapter 1: Forests: our lifeline

With reference to the structure of a forest, consider the following statements: 1. The branchy part of a tree above the stem is known as the crown. 2. The roof-like structure formed by the branches is called the root system. 3. The forest floor is the only layer found in a forest. Which of the statements given above is/are correct?

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Consider the following statements regarding the vegetation layers in a forest: 1. Giant and tall trees constitute the top layer. 2. Shrubs and tall grasses form the lowest layer of the forest. 3. Herbs form the lowest layer of vegetation in the forest. Which of the statements given above is/are correct?

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In a dense forest ecosystem, the forest floor receives minimal sunlight primarily due to:

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With reference to the role of forests in the water cycle, consider the following statements: 1. Trees release water vapour into the air through the process of condensation. 2. The forest canopy intercepts raindrops, preventing them from hitting the ground directly. 3. Forests facilitate the infiltration of water into the ground. Which of the statements given above is/are correct?

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Consider the following statements about the "forest floor": 1. The forest floor is generally dark due to the dense canopy above. 2. The forest floor is completely devoid of any dead or decaying matter. 3. The forest floor is sterile and supports no living organisms. Which of the statements given above is/are correct?

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The correct option is (c).

Explanation

Statement-wise Analysis:

Statement 1 is Correct: Decomposition is the process by which decomposers, such as bacteria and fungi, break down complex organic matter from dead plants and animals. This process converts organic compounds into simpler inorganic substances (nutrients), which are cycled back into the soil.
Statement 2 is Incorrect: Humus is a dark, amorphous substance formed during decomposition that is highly resistant to microbial action. While it decomposes very slowly, it serves as a reservoir of nutrients rather than preventing their release. Through a process called mineralization, humus is further degraded by microbes to slowly release inorganic nutrients into the soil, making them available to plants.
Statement 3 is Correct: Once decomposers and mineralization processes release inorganic nutrients (such as nitrogen, phosphorus, and potassium) into the soil solution, these nutrients are absorbed by the roots of living plants. The plants use these nutrients for growth and metabolism, thereby re-entering the food chain.