Plant Hormones

• What do plant hormones ensure about plant growth?

  They ensure growth in the right direction
• What is auxin in plants?

  Auxin is a plant growth hormone
• Where does auxin control growth in plants?

  Near the tip of shoots and roots
• What does auxin control in response to light?

  It controls growth in response to light
• What is phototropism?

  Growth in response to light
• What is gravitropism?

  Growth in response to gravity
• How is auxin produced in plants?

  It is produced in the tip of the plant
• What happens if the tip of a shoot is removed?

  No auxin is available for growth
• What does auxin promote in the shoot?

  It promotes cell elongation
• What happens to shoots when they are exposed to light?

  More auxin accumulates on the shaded side
• How do shoots respond to light?

  They bend towards the light source
• How do roots respond to gravity?

  They grow downwards towards gravity
• How do shoots grow in relation to gravity?

  They grow upwards away from gravity
• What happens to auxin distribution in roots growing sideways?

  More auxin accumulates on the lower side
• What is the effect of auxin on the lower side of a root?

  It causes the root to bend downwards
• What is the effect of auxin on the upper side of a root?

  It promotes slower growth compared to the lower side
• What happens to the shoot when it bends towards light?

  It grows faster on the shaded side
• What is the relationship between auxin and cell elongation?

  Auxin promotes cell elongation in shoots
• What are the main functions of auxin in plants?

  • Controls growth near the tips of shoots and roots
  • Promotes cell elongation
  • Regulates growth in response to light and gravity
• What are the effects of light on shoot growth?

  • Auxin accumulates on the shaded side
  • Shoots bend towards the light
  • Growth is faster on the side with more auxin
• What are the effects of gravity on root growth?

  • Roots grow downwards towards gravity
  • Auxin accumulates on the lower side
  • Growth is faster on the lower side
• What experimental setup can be used to investigate the effect of light on plant growth?

  1. Place seeds in different dishes
  2. Shine light on one side of the dishes
  3. Observe growth direction and rate
• What experimental setup can be used to investigate the effect of gravity on plant growth?

  1. Place seeds in a horizontal position
  2. Observe root and shoot growth direction
  3. Measure growth rates over time
• What are the effects of auxin on plant growth?

  • Promotes elongation in shoots
  • Inhibits elongation in roots
  • Regulates responses to light and gravity
• How many cress seeds should be put into the petri dishes?

  10 cress seeds
• What should each petri dish be lined with?

  Moist filter paper
• How should the dishes be labeled?

  Label them A, B, C
• What should you shine on the dishes from above?

  Shine a light
• How long should the cress seeds be left alone?

  One week
• What will you observe after one week?

  Their responses and growth towards light
• What is the growth response of cress seeds due to?

  Light only, if controlled
• What are the variables to control in the experiment?

  • Number of seeds used
  • Type of seeds used
  • Temperature maintained
  • Amount of water provided
  • Distance between light source and dishes
• What should be done with the petri dishes after placing the seeds?

  Store them in a stable place
• What should you do with the petri dishes to ensure stable temperature?

  Away from heat sources and draughts
• What should be used to measure the amount of water added?

  A measuring cylinder
• What should be done with the water in the experiment?

  Use the same amount for each dish
• How should the seeds be placed in the petri dishes?

  Evenly spaced apart
• What should be done to the seeds after placing them in the petri dishes?

  Cover them with moist filter paper
• What is the purpose of the experiment?

  To investigate the effect of light on growth
• How can you visualize the results of your experiment?

  By drawing labeled diagrams