Biology

Question

What is a stimulus?

A. a product of photosynthesis

B. cells in the brain

C. a specialized type of cell in an organism

D. something in the environment that affects organisms

Answer

D. Something in the environment that affects organisms.

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A stimulus is any physical or chemical change in the environment that can be detected by an organism and that leads to a response. It can be a sound, light, touch, taste, or smell, among others. The response to a stimulus can be a behavior, a physiological change, or a combination of both. Stimuli can be internal or external, and they can be positive or negative, depending on whether they elicit a desirable or undesirable response. Organisms have evolved to detect and respond to stimuli in their environment to survive and reproduce.