Final answer:
The largest level of organization in biology is the organism level, which involves living beings that can independently perform all physiological functions necessary for life. Cells combine to form tissues, which then form organs and organ systems.
Step-by-step explanation:
The largest level of organization is the organism level. An organism is a living being that can independently perform all physiologic functions necessary for life. In multicellular organisms, cells combine to form tissues, which then form organs, and ultimately organ systems that work together to maintain the life and health of the organism.