Behavior
Behavior explained in an easy to understand way:
Imagine you're sitting in a room when suddenly your phone rings, prompting you to reach over and pick it up. This scenario is quite similar to how organisms respond to internal or external stimuli, as the phone's ring acts as an external trigger that elicits a reaction from you. Just like your action of answering the phone due to its ringing, organisms react to changes in their environment or internal state, where the ringing phone represents the stimulus and your movement to answer it parallels the organism's response.
Practice Version
Behavior: An organisms response to internal or external stimulus. Behavior. In science, behavior is how an organism acts in response to its environment or changes in its surroundings.