Protozoa are best described as which of the following?

Protozoa are best described as which of the following?

• A. One-celled organisms that multiply in humans and may be free-living or parasitic
• B. Multicellular organisms
• C. Bacteria
• D. Viruses

Answer: (A)

Protozoa are single-celled, eukaryotic organisms that can live freely in the environment or as parasites in humans, and they have the ability to multiply within the host. This makes the description of one-celled organisms that multiply in humans and may be free-living or parasitic the best fit. They are not multicellular, and they differ from bacteria, which are prokaryotic, and from viruses, which are noncellular particles that must hijack a host cell to replicate. Protozoa possess a true nucleus and cellular organelles, underlying why they fit the single-celled, cellular description.

Protozoa are single-celled, eukaryotic organisms that can live freely in the environment or as parasites in humans, and they have the ability to multiply within the host. This makes the description of one-celled organisms that multiply in humans and may be free-living or parasitic the best fit. They are not multicellular, and they differ from bacteria, which are prokaryotic, and from viruses, which are noncellular particles that must hijack a host cell to replicate. Protozoa possess a true nucleus and cellular organelles, underlying why they fit the single-celled, cellular description.