2022 GS3 Answer

Q. Each year a large amount of plant material, cellulose, is deposited on the surface of Planet Earth. What are the natural processes this cellulose undergoes before yielding carbon dioxide, water and other end products ?

Question from UPSC Mains 2022 GS3 Paper

Model Answer: 

Cellulose is the primary structural component of plant cell walls and is the most abundant organic compound on Earth. After plant material dies, it undergoes a series of natural processes that break down the cellulose into simpler compounds and release carbon dioxide and water.

Decomposition of Cellulose

The decomposition of cellulose involves several natural processes, including:

  • Fragmentation: The physical breakdown of plant material into smaller pieces, such as leaves, twigs, and branches, increases the surface area available for decomposition.
  • Leaching: Rainwater and other sources of water wash away soluble compounds from plant material, such as sugars, starches, and other nutrients.
  • Chemical decomposition: Enzymes and microorganisms in the soil break down the cellulose and other complex organic compounds into simpler compounds, such as carbon dioxide, water, and humus.
  • Humification: Humus is the dark, organic material that remains after plant material has decomposed. It is rich in nutrients and helps to improve soil structure and fertility.

Factors Affecting Decomposition

Several factors can affect the rate and efficiency of cellulose decomposition, including:

  • Temperature: Decomposition is faster in warm, moist environments, such as tropical rainforests, than in cold, dry environments, such as deserts.
  • Moisture: Adequate moisture is necessary for decomposition to occur. Dry environments can slow or halt decomposition.
  • Soil acidity: The pH of the soil can affect the activity of microorganisms involved in decomposition.
  • Oxygen availability: Aerobic decomposition, which requires oxygen, is faster than anaerobic decomposition, which occurs in oxygen-poor environments.


The decomposition of cellulose is a complex, natural process that involves fragmentation, leaching, chemical decomposition, and humification. The rate and efficiency of decomposition are affected by several factors, including temperature, moisture, soil acidity, and oxygen availability. The end products of decomposition are carbon dioxide, water, and humus, which contribute to the carbon and nutrient cycles in the ecosystem.

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