Plant Hormones

• What should students be able to describe by the end of the video on plant hormones?


  How plants use hormones to respond to light and gravity
• What is phototropism?


  It is the growth of plant shoots towards light
• What hormone is suggested to control phototropism in plants?

  Auxin
• What happened when scientists removed the tips of the shoots in their experiments?


  The shoots did not grow towards the light
• What does covering the tips of the shoots with foil indicate about their sensitivity to light?


  It shows that the tips are sensitive to light
• What was the result when the lower parts of the shoots were covered with foil?


  The shoots grew towards the light as normal
• What are the stages of how shoots use auxin to grow towards light?


  1. Auxins are produced at the tip of the shoot.
  2. Auxin triggers cell growth.
  3. Light causes auxin to concentrate on the darker side.
  4. Auxin spreads down the shoot.
  5. Cells on the darker side grow faster than on the lighter side.
  6. The shoot grows towards the light.
• What is gravitropism also known as?


  Geotropism
• How does gravity affect auxin concentration in plant roots?


  Gravity causes auxin to concentrate on the lower side
• What effect does auxin have on cell growth in roots?


  Auxin inhibits cell growth in roots
• What is the result of auxin inhibiting cell growth on the lower side of roots?


  The lower side grows more slowly than the upper side
• What are the roles of gibberellins and ethylene in plants?


  • Gibberellins: Important in starting the germination of seeds.
  • Ethylene: Controls cell division and the ripening of fruits.
• What type of students need to know about gibberellins and ethylene?


  Higher-tier students
• Where can students find more questions on plant hormones?


  In the vision workbook