Phototropism

• On what side of the stem do auxins collect? (light / dark)

  Dark

  
• Do auxins move away from or towards light?

  away
• Auxins cause cell elongation
• On the dark side cells elongate
• On the light side cells remain small (short)
• Phototropism

  • Auxins cause cell elongation
  • On the dark side cells elongate
  • On the light side cells remain small (short)
  • Causes the stem to bend towards the light
• Auxins are made in the tips of stems and roots
• If the concentration of auxins is too high then cell elongation will be stopped
• Cell elongation = lengthening of a cell
• Name the THREE roles of auxins in plants?

  1. promotes growth
  2. causes apical dominance
  3. tropic movements
• Auxins are made at the apical tip and diffuse downwards.