What is the term for movement toward a chemical stimulus in organisms?

The term for movement toward a chemical stimulus in organisms is positive chemotaxis. This process occurs when an organism detects a concentration gradient of a chemical attractant and moves in the direction of higher concentration to maximize its exposure to the beneficial substance. This behavior is essential for various activities, such as foraging, reproduction, and avoiding harmful substances.

In terms of other options, negative chemotaxis refers to movement away from a chemical stimulus, while kinesis involves a change in the rate of movement in response to stimuli, but not necessarily towards or away from it. Orthokinesis describes the alteration of movement speed in relation to the intensity of a stimulus rather than a directional response. Understanding these distinctions is crucial in grasping the different ways organisms interact with their chemical environment.