AP BIOLOGY

Detailed explanation-1: -The simplest type of response is a direct one-to-one stimulus-response reaction. A change in the environment is the stimulus; the reaction of the organism to it is the response.

Detailed explanation-2: -The immediate reaction by an individual to a particular stimulus is called response.

Detailed explanation-3: -The correct option is A sensitivity. The stimulus(singular) is any change in the organism’s internal or external environment that causes the organism to react. The ability of an organism to respond to external stimuli is called sensitivity.

Detailed explanation-4: -In the nervous system, internal and external stimuli can elicit two different categories of responses: an excitatory response, normally in the form of an action potential, and an inhibitory response.

Detailed explanation-5: -excited by three types of stimuli-mechanical, thermal, and chemical; some endings respond primarily to one type of stimulation, whereas other endings can detect all types.