Michigan Test for Teacher Certification (MTTC) Secondary Integrated Science Practice test

The correct answer is the cell theory, which is a fundamental concept in biology that asserts all living organisms are composed of cells. This theory has three main principles: first, that all living things are made up of one or more cells; second, that the cell is the basic unit of life; and third, that all cells arise from pre-existing cells. This understanding is critical because it establishes the cell as the foundational unit of structure and function in all living organisms, facilitating further study of biology, including cellular processes, genetics, and the mechanisms of life itself.

The other theories mentioned, while significant in their own right, do not pertain to the cellular composition of living organisms. Germ theory focuses on the role of microorganisms in disease, evolution theory discusses the mechanisms behind the diversity of life and adaptation over time, and energy theory pertains to the transfer and transformation of energy in biological systems. Each of these has its own relevance in biology but does not specifically address the cellular structure of organisms.