What is the basic unit of structure and function in living organisms?

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

Answer: (A)

Cells are the basic unit of structure and function in living organisms. They are the smallest units that can carry out all life processes, from metabolism and energy use to growth and reproduction. In multicellular organisms, cells come together to form tissues, tissues build organs, and organs organize into organ systems, but every higher level of organization ultimately depends on the activities of individual cells. Inside cells are specialized structures called organelles, such as the nucleus and mitochondria, that perform specific tasks necessary for the cell to function. Organelles are components within cells, not the smallest unit of life themselves, and tissues and organs are larger collective structures made from cells.