Which describes an organism that consists of a single cell?

• A. Multicellular
• B. Organism
• C. Unicellular
• D. Nucleic Acids

Answer: (C)

The main idea is that some organisms are made of just one cell. When a single cell carries out all the life processes—metabolism, growth, responding to the environment, and reproduction—that organism is described as unicellular. Classic examples include bacteria and yeast, which function entirely within one cell. In contrast, multicellular organisms are built from many specialized cells working together, so they aren’t described as single-cell. The term organism is broad and can refer to either single-celled or many-celled beings, so it doesn’t specify the number of cells. Nucleic acids are molecules that store genetic information, not organisms. So the description of a one-cell organism fits unicellular perfectly.