Video Transcript
Which of the following cannot be
classified into a kingdom in Whittaker’s system of classification? (A) Humans, (B) bacteria, (C)
yeast, (D) prions, or (E) archaea.
This question is asking us to
recall Whittaker’s system of classification, which included five distinct kingdoms,
and to choose the answer option that is not able to be placed into one of those five
kingdoms. The five kingdoms described in
Whittaker’s system are monera, protist, plant, fungi, and animal. All five of these kingdoms have in
common that they’re made of living organisms that consists of at least one cell. Members of the monera kingdom are
prokaryotes; it’s single-celled organisms that do not possess a nucleus. The protist kingdom was devised to
encompass microscopic life that is neither plant fungus nor animal.
The plant kingdom generally
includes all multicellular autotrophs, which are separate from heterotrophic fungi
that do not photosynthesize. And multicellular heterotrophs that
generally move about are considered animals. Now let’s take a closer look at our
five answer choices. Humans are complex multicellular
organisms that have the ability to move about. We are considered animals. Both archaea and bacteria are
single-celled organisms that do not possess a nucleus. They possess some physical
differences and live in different environments, but they’re both classified as
monera.
Yeast are unicellular organisms
that do not move around on their own and absorb their nutrition from their
surroundings. They also have a cell wall which
contains a material called chitin. These traits classify yeast as a
member of the kingdom fungi. Since each of the organisms we’ve
identified already can be classified in one of the five kingdoms and we’re looking
for the one organism which cannot, we could conclude at this point that the correct
answer is prions. But let’s take a closer look at
what a prion is. A prion is an abnormally folded
protein which has the ability to interact with normal proteins and cause them to
become abnormally folded as well. Since prions are proteins, they’re
not made of cells, which means that prions cannot be classified in Whittaker’s
five-kingdom system.
