Final answer:
A mushroom is considered a heterotroph because it obtains its nutrients by decomposing organic matter through extracellular digestion. It relies on consuming organic material from its surroundings to sustain its growth and reproduction.
Step-by-step explanation:
The Mushroom as a Heterotroph
A mushroom is considered a heterotroph due to its mode of nutrition. Heterotrophs are organisms that cannot produce their own food and rely on consuming organic matter from other sources. Mushrooms obtain their nutrients by decomposing organic matter, such as dead plants or animals, through the process of extracellular digestion.
Extracellular Digestion in Mushrooms
Mushrooms secrete digestive enzymes into their surrounding environment to break down complex organic matter into simpler molecules. These enzymes break down carbohydrates, proteins, and lipids present in organic material into smaller units that can be absorbed by the mushroom's cells. The nutrients are then transported and utilized for growth and reproduction.
Example
For example, consider a mushroom growing on a fallen tree. The mushroom's mycelium (thread-like structures) will extend into the decaying wood, secreting digestive enzymes to break down the cellulose and lignin present in the tree. As the organic matter is broken down, the mushroom absorbs the resulting nutrients, using them for its own metabolic needs. This dependence on external food sources classifies mushrooms as heterotrophs.
Learn more about heterotrophs