• Stimuli are changes in environmet e.g. temperature and light
• Plants have receptors which can detect stimulis, resulting in the growth of the plant
• The process of growth from the stimuli is called 'tropism'
• Tropism that involves light is known as 'phototropism' whereas Tropism that involves gravity is called 'geotropism'
• The link between resceptors and response are the 'plant hormones or 'plant growth regulators'
• auxin is a type of plant hormone