Question

what is stimuli??..
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Answer 1

Answer:

physiology, a stimulus is a detectable change in the physical or chemical structure of an organism's internal or external environment. The ability of an organism or organ to detect external stimuli, so that an appropriate reaction can be made, is called sensitivity

Explanation:

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Answer 2

Answer:

A reaction occurs in an organism because of the signal sent by the CNS.

Explanation:

The sensory organs detect all types of changes in the environment and send appropriate signals to the CNS in the form of stimulus.

The stimulus/ inputs are then processed and analysed. These are then sent to the brain/ different parts of the body.