Video: Recognizing a Correct Example of What Is Excluded from the Whittaker System of Classification

Which of the following cannot be classified into a kingdom in Whittaker’s system of classification? [A] Humans [B] Bacteria [C] Yeast [D] Prions [E] Archaea

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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.

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