plant hormone

• what is phototropism?


  growth towards the light
• what is gravitropism?


  growth towards gravity
• how does shoots use auxin to grow towards the light?

  1. auxin is produced at the very tip of the shoot
  2. in shoots, auxin triggers cell growth
  3. light causes auxin to concentrate on the darker side of the shoot tip
  4. auxin spreads down the shoot
  5. cells on the darker side grow faster than the lighter side = shoot grows towards the light
• what is an example of a plant hormone?

  Auxin
• how does the shoot use auxin grow towards gravity?

  1. gravity causes the auxin to concentrate on the lower side
  2. the lower side now grows more slowly than the upper side
  3. roots grow towards the force of gravity
• what is the purpose of gibberellins?


  the germination of seeds
• what is the purpose of the chemical ethene?

  controls cell division and the ripening of fruits