The rate of decomposition in a particular climatic condition is quicker, if detritus is rich in ________ & ________
Answer & explanation
Correct answer: option 3
The correct answer is Option (3) → Sugars, Nitrogen
Decomposition is the breakdown of dead organic matter (detritus) into simple inorganic substances by decomposers. Its rate depends on the chemical make-up of the detritus and on the climate.
Option (1) Sugars, Phosphorus — Incorrect. Sugars do speed it up, but the book names nitrogen as the second factor, not phosphorus.
Option (2) Lignin, Phosphorus — Incorrect. Lignin slows decomposition. It is the tough material of wood that microbes break down only slowly.
Option (3) Sugars, Nitrogen — Correct. Detritus rich in nitrogen and water-soluble substances like sugars is easy food for decomposers, so it breaks down fast.
Option (4) Lignin, Chitin — Incorrect. These are the two substances that make decomposition slower. Chitin is the hard material of insect bodies and fungal walls.
NCERT Extract:
Decomposition – “… Decomposition is largely an oxygen-requiring process. The rate of decomposition is controlled by chemical composition of detritus and climatic factors. In a particular climatic condition, decomposition rate is slower if detritus is rich in lignin and chitin, and quicker, if detritus is rich in nitrogen and water-soluble substances like sugars.”