Video Transcript
Organisms belonging to kingdom
Fungi are heterotrophic. How do the majority of organisms in
the kingdom Fungi obtain their nutrition? (A) They ingest and digest other
organisms, obtaining nutrients from the breakdown of their tissues. (B) They act as parasites and enter
the bloodstream of animals to obtain nutrients. (C) They absorb nutrients from
organic matter in their environment, such as dead tissues. Or (D) they produce it themselves
through the process of photosynthesis.
The question tells us that
organisms in kingdom Fungi are heterotrophic. What does this mean? A heterotroph is an organism that
must obtain its nutrition from organic matter in another living, or once living,
organism in their surroundings. As they rely on other organisms for
their nutrition, heterotrophs are sometimes known as consumers. In contrast, autotrophs, like most
plants, are often known as producers, as they can make their own food from simple
inorganic materials by converting them into organic materials, such as sugars.
The method most plants use to
produce their nutrition is through a process called photosynthesis, which also
requires light energy, usually provided by the Sun. As we know that this is a feature
of autotrophic organisms like plants, and not of heterotrophic organisms like fungi,
we can eliminate answer option (D).
There are a few different types of
heterotrophic organisms that we can distinguish between: holozoic organisms,
parasitic organisms, and saprophytic organisms. Holozoic organisms ingest solid,
liquid, or gaseous organic food particles that are obtained from another
organism. Once these food particles are
ingested, the holozoic organism uses enzymes within their body to digest large
nutrients into smaller ones that can be absorbed and used by the cells that require
them. This is described in answer option
(A).
If holozoic nutrition sounds
familiar, it’s because humans are examples of holozoic organisms, as are most other
animals, and even some single-celled organisms, like the amoeba. Fungi, however, are not holozoic
organisms, so we can eliminate option (A).
Parasites are heterotrophic
organisms that live in or on a host, and obtain their nutrition at the host’s
expense. Answer option (B) is describing
parasitic nutrition. And a specific example that enters
the bloodstream of animals in this manner is the protist Plasmodium, which
causes malaria in humans. While some fungi can be perceived
to be parasitic as they cause infections in animals, like humans, obtaining their
nutrition at our expense, this is not the case for the majority of fungi, so we can
also eliminate answer option (B).
Instead, the majority of fungi are
saprophytic organisms. Saprophytes tend to obtain
nutrition from dead or decaying organic matter by releasing enzymes into their
extracellular environment. These enzymes break down nutrients
in decaying organisms in their surroundings into smaller molecules that can then be
absorbed into the saprophyte cells to be used as required.
This means that we have found the
correct answer to this question. The way that the majority of
organisms in kingdom Fungi obtain their nutrition is (C). They absorb nutrients from organic
matter in their environment, such as dead tissues.
