A group of similar cells functioning together is called a ___.

• A. Tissue
• B. Organ
• C. Cell
• D. Organ System

Answer: (A)

In biology, a tissue is a group of similar cells that work together to perform a common function. When cells of the same type come together, they specialize and organize to carry out specific tasks—like muscle tissue contracting to produce movement or nerve tissue transmitting signals. This collection of similar cells forms a tissue, which then serves as the building block for organs, which combine different tissues to perform more complex roles, and organs of an organ system work together to keep the organism alive.

So the phrase “group of similar cells functioning together” matches the definition of tissue best. An organ is made of multiple tissues, not just a single tissue; an organ system is a collection of organs; a cell is, of course, a single cell, not a group.