What is a cell?

• A. A group of tissues
• B. A molecule
• C. The basic unit of life
• D. The result of organ formation

Answer: (C)

A cell is the basic unit of life—the smallest structure capable of carrying out the processes that define living things. Cells manage metabolism, respond to their environment, grow, and—often—reproduce to form new cells. They are the building blocks of all organisms, from single-celled bacteria to complex multicellular plants and animals, with tissues and organs built from many cells. A single cell has essential components like a surrounding membrane, cytoplasm where activities occur, and genetic material that directs its functions. This idea is captured in cell theory: all living things are made of cells, and new cells come from existing cells.

A group of tissues is a collection of similar cells working together, which is a higher level of organization than a single cell. A molecule is far too small to carry out life processes on its own. The result of organ formation is an organ, not a cell.