plant hormones

• What are plant hormones important for?

  Controlling a plant’s growth and development
• What are auxins?

  Plant hormones that control growth at the tips of shoots and roots
• How do auxins move through the plant?

  They move in solution, dissolved in water
• Where is auxin produced in the plant?

  In the tip of the plant
• What effect does auxin have on shoot growth?

  It promotes growth in the shoot
• What effect does auxin have on root growth?

  It inhibits growth in the root
• What are the roles of auxins in plant responses to light and gravity?

  They are involved in phototropism and gravitropism
• How do shoots respond to light according to auxin distribution?

  They accumulate more auxin on the shaded side, causing bending towards light
• How do shoots respond to gravity according to auxin distribution?

  More auxin accumulates on the lower side, causing the shoot to bend upwards
• How do roots respond to gravity according to auxin distribution?

  More auxin accumulates on the lower side, inhibiting growth and causing bending downwards
• How do roots respond to light according to auxin distribution?

  More auxin accumulates on the shaded side, inhibiting growth and causing bending downwards
• What is a practical way to investigate plant growth responses to light?

  1. Place 10 cress seeds in three Petri dishes with moist filter paper.
  2. Shine light on one dish from above and two from different directions.
  3. Observe the seedlings after one week for growth towards light.
  4. Control variables like temperature and distance from the lamp.
• What is gibberellin and its role in plant growth?

  Gibberellin is a plant hormone that stimulates seed germination, cell growth, and flowering
• How do auxin and gibberellin work together?

  They can work together to significantly enhance plant growth
• What is the role of ethene in plants?

  Ethene stimulates the shedding of leaves and ripening of fruit
• How does ethene affect leaf shedding?

  It weakens the cells connecting the leaf to the plant, causing leaves to fall off
• What happens to ethene production as leaves age?

  Leaves produce more ethene as they get older
• What does ethene stimulate in fruit?

  It stimulates enzymes that cause fruit to ripen
• How are plant hormones used as selective herbicides?

  • Selective herbicides are developed using auxin.
  • They affect broad-leaved plants but not grasses or cereals.
  • They disrupt normal growth patterns in weeds, leading to their death.
• How does rooting powder help in growing cuttings?

  • Rooting powder contains auxins.
  • It enables cuttings to produce roots rapidly.
  • This allows for quick production of clones of desirable plants.
• How can auxins and gibberellins be used to produce seedless fruit?

  • Auxins and gibberellins can be applied to unpollinated flowers.
  • This allows fruit to grow without seeds.
  • The result is parthenocarpic fruit, which has no seeds.
• How can gibberellin be used to control seed dormancy?

  • Gibberellin can alter dormancy in seeds.
  • It allows seeds to germinate under non-traditional conditions.
  • It ensures uniform germination in a batch of seeds.