Fungi, like the toadstool mushroom shown in the picture, are heterotrophs that obtain
nutrition from dead and decaying organisms. What classification of heterotrophic organisms do they belong to?
This question asks us about classifications of heterotrophic organisms. Let’s start by defining what heterotrophic organisms, which are sometimes simply
referred to as heterotrophs, are before we explore the different types to work out
the correct answer to this question.
A heterotrophic organism is an organism that must obtain its nutrition by consuming
the organic matter from another living, or once living, organism. Humans are an example of organisms that rely on other organisms to obtain our
nutrition. Everything that we eat, whether it is plant matter like fruit and vegetables, fungal
matter like mushrooms, or animal matter like meat and fish, was once a living
organism. Humans belong to an even more specific class of heterotroph: holozoic
heterotrophs. Holozoic organisms are those that obtain nutrition by ingesting and internally
digesting solid, liquid, or gaseous food particles within their bodies.
Another group of heterotrophs are parasites, which obtain their nutrition by feeding
on a host organism. Parasites tend to obtain their nutrition at their host’s expense. For example, leeches obtain their nutrition by feeding on another organism’s blood,
which would definitely be detrimental to the health of the host.
A third type of heterotrophic organisms are saprophytes. The prefix sapro- means rotting, while “phyte” means feeding. So saprophytes feed off dead or rotting tissues to obtain their nutrition. They usually do this by releasing extracellular enzymes out of their cells to digest
organisms that are often dead and decaying and then absorbing the smaller molecules
that the organic matter is broken down into.
Most fungi, including the toadstool mushrooms of interest to us in this question,
obtain their nutrition from dead and decaying organisms in this manner. This means that we have found the correct answer to this question. As our question asks us about fungi, which are heterotrophs that obtain nutrition
from dead or decaying organisms, the correct answer is saprophytes.