Plants

• Plants respond to stimuli
• plant responses are called tropisms
• There are three tropisms:

  hydrotropism

  phototropism

  geotropism
• Tropisms are positive when they go towards the stimulus, and negative when they go away from the stimulus
• Roots have a positive geotropism and a negative phototropism
• Shoots have a positive phototropism and a negative geotropism
• Auxin is produced at the tips of stems and diffuses backwards to stimulate the cell elongation process in response to assist the positive phototropism