Decomposers break down complex organic matter into inorganic substances like carbon dioxide, water and nutrients and the process is called decomposition. Dead plant remains such as leaves, bark, flowers and dead remains of animals, including fecal matter, constitute detritus, which is the raw material for decomposition.

Fragmentation, leaching and catabolism are some of the important steps of decomposition. Study the following statements [(i), (ii) and (iii)] regarding these and select the correct option.

(i) Detritivores (e.g., earthworm) breakdown detritus into smaller particles.

(ii) Water soluble inorganic nutrients go down into soil horizon and get precipitated as unavailable salts.

(iii) Decomposers (e.g., bacteria and fungi) secrete digestive enzymes and degrade detritus into simpler inorganic substances.

Leaching - ii

Fragmentation - i

Catabolism - iii

The correct option is 3 .

Leaching - ii

Fragmentation - i

Catabolism - iii

The process of decomposition can be categorised as fragmentation of detritus, leaching and catabolism. Fragmentation of detritus is the process that causes breakdown of detritus into smaller particles. It is primarily due to the action of detritus feeding invertebrates (detritivores, e.g., termites, earthworms, etc.). The detritus gets pulverised when passing through the digestive tracts of animals. Due to fragmentation, the surface area of detritus particles is greatly increased.

The extracellular enzymes released by bacteria and fungi carry out catabolism, i.e., enzymatic conversion of the decomposing detritus to simpler and inorganic substances.

Leaching is the process by which dissolved nutrients are moved into lower layers of soil or groundwater to form unavailable salts.