Consider the following statements about the decomposition in soil: 1. Dead plants and animals in the soil are decomposed exclusively by chemical weathering, not by organisms. 2. Decomposition releases nutrients back into the soil. 3. These nutrients are then absorbed by plants. Which of the statements given above is/are correct?

The correct option is (c) 2 and 3 only. Explanation Decomposition is a vital ecological process where complex organic matter from dead plants and animals is broken down into simpler inorganic substances. This process is primarily driven by biological agents known as decomposers. - Statement 1 is Incorrect: Decomposition is not achieved exclusively by chemical weathering. It is predominantly a biological process carried out by microorganisms such as bacteria and fungi (saprophytes), as well as detritivores like earthworms. Chemical weathering refers to the breakdown of rocks and minerals, not the biological breakdown of organic biomass. - Statement 2 is Correct: The primary function of decomposition is to convert organic matter back into inorganic substances. This process, often called mineralization, releases essential nutrients (such as nitrogen, phosphorus, and potassium) back into the soil pool. - Statement 3 is Correct: Once nutrients are released into the soil in inorganic forms, they become available for uptake by plant roots. Plants absorb these nutrients to synthesize proteins, chlorophyll, and other essential compounds required for growth and development. Key Takeaway: Decomposition is a biological process driven by microorganisms that recycles nutrients from dead organic matter back into the soil, making them available for plant absorption.

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

mcqeasy

Consider the following statements about the decomposition in soil:

Dead plants and animals in the soil are decomposed exclusively by chemical weathering, not by organisms.
Decomposition releases nutrients back into the soil.
These nutrients are then absorbed by plants.

Which of the statements given above is/are correct?

Official previous-year question

Verified 1 Aug 2026.

Options

A1 and 2 only
B2 only
C2 and 3 only
D1, 2 and 3

Did you get this right?

Solution

The correct option is (c) 2 and 3 only.

Explanation

Decomposition is a vital ecological process where complex organic matter from dead plants and animals is broken down into simpler inorganic substances. This process is primarily driven by biological agents known as decomposers.

Statement 1 is Incorrect: Decomposition is not achieved exclusively by chemical weathering. It is predominantly a biological process carried out by microorganisms such as bacteria and fungi (saprophytes), as well as detritivores like earthworms. Chemical weathering refers to the breakdown of rocks and minerals, not the biological breakdown of organic biomass.
Statement 2 is Correct: The primary function of decomposition is to convert organic matter back into inorganic substances. This process, often called mineralization, releases essential nutrients (such as nitrogen, phosphorus, and potassium) back into the soil pool.
Statement 3 is Correct: Once nutrients are released into the soil in inorganic forms, they become available for uptake by plant roots. Plants absorb these nutrients to synthesize proteins, chlorophyll, and other essential compounds required for growth and development.

Key Takeaway: Decomposition is a biological process driven by microorganisms that recycles nutrients from dead organic matter back into the soil, making them available for plant absorption.

Your note

More from Chapter 1: Crop production and management

Which one of the following is an organic soil amendment derived from the decomposition of plant or animal waste?

easy

With reference to the cropping patterns in India, consider the following statements: 1. Kharif crops are generally sown in the rainy season which spans from June to September. 2. Wheat, gram, and mustard are examples of Kharif crops. 3. Rabi crops are grown during the winter season from October to March. Which of the statements given above is/are correct?

easy

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?

medium

With reference to agricultural implements, consider the following statements: 1. A ploughshare is the strong triangular iron strip found in a plough. 2. A hoe is a tool used exclusively for sowing seeds. 3. A cultivator is a manual tool used for harvesting crops. Which of the statements given above is/are correct?

medium

Consider the following statements regarding the sowing of seeds: 1. Damaged seeds are generally lighter than healthy seeds and float on water. 2. The traditional tool for sowing seeds is shaped like a flat blade. 3. A seed drill ensures that seeds are covered by soil after sowing to protect them from birds. Which of the statements given above are correct?

medium

Keep practising Chapter 1: Crop production and management

Work through every question from this NCERT chapter.

Browse all NCERT Class 8 Science chapters

The correct option is (c) 2 and 3 only.

Explanation

Statement 1 is Incorrect: Decomposition is not achieved exclusively by chemical weathering. It is predominantly a biological process carried out by microorganisms such as bacteria and fungi (saprophytes), as well as detritivores like earthworms. Chemical weathering refers to the breakdown of rocks and minerals, not the biological breakdown of organic biomass.
Statement 2 is Correct: The primary function of decomposition is to convert organic matter back into inorganic substances. This process, often called mineralization, releases essential nutrients (such as nitrogen, phosphorus, and potassium) back into the soil pool.
Statement 3 is Correct: Once nutrients are released into the soil in inorganic forms, they become available for uptake by plant roots. Plants absorb these nutrients to synthesize proteins, chlorophyll, and other essential compounds required for growth and development.

Key Takeaway: Decomposition is a biological process driven by microorganisms that recycles nutrients from dead organic matter back into the soil, making them available for plant absorption.