What is the name of a small, unsegmented roundworm that is often too small to be seen with the naked eye?

• A. Nematode
• B. Parasite
• C. Perennial
• D. Phloem

Answer: (A)

Nematodes are slender, threadlike worms that have no body segments and are often microscopic or just barely visible without a microscope. That perfectly matches the description of a small, unsegmented roundworm, so the best name is nematode.

A parasite is a general term for any organism that lives on or in another organism and benefits at the host’s expense, which can describe many organisms, not specifically the tiny unsegmented worm. Perennial refers to a plant that lives for more than two years, and phloem is the plant tissue that transports sugars. These terms aren’t about the worm itself, so they don’t fit the description as precisely.