- Stimuli are changes in the environment. These could be temperature changes or light changes.

- Plants have receptors which can detect stimuli. The receptors then connect with the response section using plant hormones such as Auxin.

- The responses are often in the form of growth. This type of response is called a 'tropism.' If the stimuli is changes in light the response is known as 'phototropism.' The other type of tropism is a response to gravity, known as 'geotropism.'