Parasites are multicellular organisms that live in or on their hosts.

• A. True
• B. False
• C. Not always; some parasites are unicellular
• D. Both animals and plants can be parasites

Answer: (B)

Parasites can be either unicellular or multicellular, so the statement that they are always multicellular isn’t correct. Some parasites are single-celled organisms called protozoa, such as Giardia or Plasmodium, which live inside hosts or on their surfaces. Others are multicellular worms like nematodes and flatworms, and there are even parasitic plants that attach to hosts. The idea of parasitism describes the relationship to the host, not a fixed level of cellular complexity, so recognizing both unicellular and multicellular forms is essential.