Which of the following is mismatched? Atom - The smallest unit of matter participating in a chemical reaction Cell - The basic structural and functional unit of an organism Molecule - Two or more atoms joined together Organ - Structure composed of two or more cells

Organ - Structure composed of two or more cells

Explanation:

Organ is a group of tissue that is specified to perform similar function. In higher organisms organ combine to form organ system such as Liver.

Two or more cells that will perform similar function are combined to form a tissue not an organ. Tissue is an organizational levels that lies between cells and organs.

The organizational levels of human are cells, tissues, organs, organ systems, and the human organism.