The correct Answer is A
Explanation
Decomposition is a vital ecological process involving the breakdown of complex organic matter (detritus) into simpler inorganic substances. This process occurs through several distinct stages, each characterized by specific biological and chemical transformations.
Statement-wise Analysis
- A. Fragmentation - 2. Breakdown of detritus into smaller particles by detritivores
Correct: Fragmentation is the initial step in decomposition where detritivores (e.g., earthworms) break down detritus into smaller pieces. This action increases the surface area for microbial action.
- B. Leaching - 3. Water-soluble nutrients move down soil profile
Correct: Leaching is the process by which water-soluble inorganic nutrients percolate down into the soil horizon and get precipitated as unavailable salts. This occurs after fragmentation.
- C. Catabolism - 1. Enzymatic degradation into simpler inorganic forms
Correct: Catabolism involves the enzymatic breakdown of complex organic matter by bacteria and fungi into simpler inorganic substances. This is a key stage in decomposition.
- D. Humification - 4. Formation of dark, colloidal, resistant substance
Correct: Humification is the process leading to the accumulation of a dark-coloured amorphous substance called humus. Humus is highly resistant to microbial action and undergoes decomposition at an extremely slow rate. It is colloidal in nature and acts as a reservoir of nutrients.
Key Takeaway
Decomposition involves a sequence of processes: fragmentation by detritivores, leaching of water-soluble nutrients, catabolism by microbes, and humification leading to humus formation.