AP BIOLOGY

Detailed explanation-1: -Organs are grouped into organ systems, in which they work together to carry out a particular function for the organism. For example, the heart and the blood vessels make up the cardiovascular system.

Detailed explanation-2: -Therefore, molecules combine to form cells, cells combine to form tissues, tissues combine to form organs, organs combine to form organ systems, and organ systems combine to form organisms.

Detailed explanation-3: -We know it all starts with the cell. And for some species it ends with the cell. But for others, the cells come together to form tissues, tissues form organs, organs form organ systems, and organ systems combine to form an organism.

Detailed explanation-4: -The correct option is D Organ system. A group of organs working together to perform a specific function is called an organ system. An example of an organ system is the circulatory system, which includes different organs like the heart, arteries, veins, and capillaries.