Which of the following is NOT an example of an organ system?

The correct answer is Photosynthetic because it is not classified as an organ system in biological terms. Organ systems are groups of organs that work together to carry out complex functions essential for the survival and health of an organism.

In contrast, the photosynthetic process refers to the method through which plants, algae, and some bacteria convert light energy into chemical energy, specifically glucose, using carbon dioxide and water. While photosynthesis is crucial for the life of plants and has significant ecological impacts, it does not constitute an organ system itself.

In the context of biology, the other options represent established organ systems in organisms. The nervous system coordinates responses to stimuli, the respiratory system enables the exchange of gases, and the circulatory system facilitates the transport of substances throughout the body. Each of these involves multiple organs that function collectively to ensure the body operates effectively, distinguishing them clearly from the process of photosynthesis.