What are the organisms called that physically and chemically break down complex dead organic remains?
Answer & explanation
Correct answer: option 2
The correct answer is Option (2) → Decomposers
Dead plant and animal remains, called detritus, are broken down in steps. In fragmentation, detritivores such as earthworms break detritus into small pieces; this is a physical breakdown. In catabolism, bacterial and fungal enzymes break it down chemically into simple inorganic substances. The book groups these organisms that break down complex organic matter as decomposers.
Option (1) Scavengers — Incorrect. Scavengers, such as vultures, eat the bodies of dead animals as food. They do not turn organic remains into simple inorganic substances, and the book does not name them in decomposition.
Option (2) Decomposers — Correct. Decomposers break down complex organic matter into inorganic substances like carbon dioxide, water and nutrients. This is decomposition.
Option (3) Both scavengers and decomposers — Incorrect. Only decomposers do this job, so “both” is wrong.
Option (4) Parasites — Incorrect. Parasites take food from a living host. They do not break down dead remains.
NCERT Extract:
Decomposition – “… Similarly, 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. The important steps in the process of decomposition are fragmentation, leaching, catabolism, humification and mineralisation. Detritivores (e.g., earthworm) break down detritus into smaller particles. This process is called fragmentation.”