Question

Match the following.

Column I	Column II
A. Fragmentation	1. Degradation of humus into inorganic nutrients
B. Leaching	2. Breakdown of detritus into small particles
C. Humification	3. Precipitation of inorganic nutrients
D. Mineralisation	4. Accumulation of dark coloured substance

• A. A-1, B-2, C-4, D-3
• B. A-2, B-3, C-4, D-1
• C. A-3, B-4, C-2, D-1
• D. A-2, B-3, C-1, D-4

Answer 1

The correct option is B A-2, B-3, C-4, D-1

Decomposition is a process in which complex organic matter are broken down to simpler inorganic substances like carbon, water and nutrients by organism known as decomposers (e.g: earthworm, bacteris, fungi, etc.). Dead remains of plants (leaves, bark, flowers, etc.) and dead remains of animals, including faecal matter is known as detritus. It is the raw material for decomposition. The process of decomposition involves the following steps:

1. Fragmentation: Detritus gets broken down into smaller particles by detrivores.
2. Leaching: The water soluble inorganic nutrients present in the fragmented components, percolates into the soil and gets precipitated as unavailable salts.
3. Catabolism: Detritus is further broken down by the enzymes of bacteria and fungi into simpler inorganic substances.
4. Humification: A dark coloured amorphous substance known as humus gets accumulated. It is resistant to microbial action and undergoes slow decomposition. Humus is colloidal in nature and forms a reservoir of nutrients.
5. Mineralisation: Humus is further degraded by some microbes to releases inorganic nutrients.