2.79 Plants and Stimuli

• Stimuli is the changes in the environment such as temperature or light changes. 
• The plant has receptors that can detect stimuli and turn that into a response, usually the responses make them grow called tropism. 
• Tropism involves light is called phototropism, gravity, geotropism. 
• The connection between the receptors and response usually take to place plant hormones, such as auxin. 
• Auxins are a class of plant growth substances its role in the plant is usually structure and growth.