Question

Describe the process of decomposition with a diagram.

Hint:

Five steps: fragmentation, leaching, catabolism, humification, mineralization.

Answer 1

Step 1: Define decomposition:
Decomposition is the process by which decomposers (bacteria and fungi) break down complex organic matter in dead plant and animal remains (detritus) into simpler inorganic substances.

Step 2: List the steps in order:
The main steps are: (1) Fragmentation - detritivores like earthworms break detritus into smaller particles; (2) Leaching - water-soluble inorganic nutrients seep into the soil; (3) Catabolism - bacterial/fungal enzymes degrade detritus into simpler compounds; (4) Humification - leads to accumulation of a dark, amorphous substance called humus that is resistant to microbial action; (5) Mineralization - humus is further degraded, releasing inorganic nutrients back to the soil.

Step 3: Note the controlling factors:
Decomposition is faster when detritus is rich in nitrogen and sugars, and is favoured by warm, moist conditions; it slows down when detritus is rich in lignin and chitin.

Final Answer:
Decomposition converts detritus into simpler inorganic substances via fragmentation, leaching, catabolism, humification and mineralization, and releases nutrients back into the soil for reuse by producers (a diagram would show detritus arrows flowing through each of these five stages back to the soil nutrient pool).