Q.Is the common edible mushroom an autotroph or a heterotroph?

Let’s begin with something you already know. Think of a fallen leaf in your garden. Over a few weeks, it turns brown, becomes brittle, and eventually crumbles into the soil. You don’t see it “disappear” — it just becomes part of the earth again. That slow, invisible breakdown is the simplest picture of decomposition.

Now, in your NCERT textbook for subjects like Biology or Environmental Studies (which you may encounter in a commerce/humanities context as part of general awareness or ecology), decomposition is defined as the process by which dead organic matter — dead plants, dead animals, fallen leaves, even waste products — is broken down into simpler substances like carbon dioxide, water, and minerals. These simpler substances then return to the soil, air, and water, ready to be used again by living plants.

The agents that do this work are mostly microorganisms — bacteria and fungi — along with some insects and worms (called detritivores). They are nature’s cleanup crew. When you see a mushroom growing on a rotting log, that mushroom is a fungus actively decomposing the wood.

The process itself happens in a few overlapping stages, though you don’t need to memorise them as a list of formulas. Here is the intuitive sequence:

• Fragmentation: The dead material is physically broken into smaller pieces by earthworms, insects, or even wind and rain. A dead leaf becomes leaf litter.
• Leaching: Water seeps through the fragments, dissolving and carrying away water-soluble nutrients like sugars and amino acids. This is why rain helps speed up decay.
• Catabolism: This is the chemical core. Enzymes from bacteria and fungi break down complex molecules (like cellulose in plant cell walls or proteins in animal tissue) into simpler ones — carbon dioxide, water, and mineral salts.
• Humification: A dark, spongy, nutrient-rich substance called humus is formed. Humus is not fully decomposed; it is a stable, long-lasting organic material that improves soil structure and water-holding capacity. It gives forest soil that rich, earthy smell.
• Mineralisation: The final step where even humus is slowly broken down, releasing inorganic nutrients like nitrogen, phosphorus, and potassium back into the soil for plants to absorb. …