Plant Hormones

• What is the role of auxins in plants?

  They control growth at shoot and root ends
• How do plants respond to stimuli compared to animals?

  Plants respond more slowly than animals
• How do plants maximize photosynthesis?

  By growing shoots towards light
• What is the effect of auxins on shoot growth?

  They stimulate growth in shoots
• What is phototropism in plants?

  It is a response to light
• What is geotropism in plants?

  It is a response to gravity
• What happens to auxins when produced in the tips of shoots?

  They diffuse backwards along the shoot
• How do auxins behave in roots compared to shoots?

  They inhibit growth in roots
• What is the relationship between auxins and light in shoots?

  Auxins accumulate on the shaded side
• How do shoots respond to gravity?

  They grow away from the ground
• What is the effect of auxins on root growth when exposed to light?

  They cause the upper side to grow faster
• If a root is exposed to light, where do auxins accumulate?

  On the lower shaded side
• How do auxins affect root curvature in response to gravity?

  They inhibit growth on the lower side
• What are the key responses of plants to light and gravity?

  • Phototropism: Shoots grow towards light (positively phototropic)
  • Geotropism: Shoots grow away from gravity (negatively geotropic)
  • Roots grow away from light (negatively phototropic)
  • Roots grow towards gravity (positively gravitropic)
• How do auxins influence the growth direction of shoots and roots?

  • In shoots: Auxins stimulate growth on shaded side
  • In roots: Auxins inhibit growth on shaded side
  • Result: Shoots curve towards light; roots curve downwards
• What are the three plant hormones discussed in the video?

  Auxin, gibberellin, and ethylene
• What is the primary function of auxin in plants?

  It stimulates plant growth
• How can auxin be used in tissue culture?

  By adding auxin to stimulate growth
• What happens when cuttings are treated with auxin powder?

  They produce roots and grow into new plants
• How do auxins function as selective weed killers?

  They disrupt growth patterns in broad-leaved weeds
• What are the three main uses of gibberellin?

  Controlling dormancy, inducing flowering, growing larger fruit
• What is dormancy in seeds?

  Period before growth starts
• How can farmers use gibberellin to increase crop yield?

  By inducing germination at optimal times
• How does gibberellin affect flowering in plants?

  It can induce flowering on demand
• What is the effect of gibberellin on seedless fruit?

  It helps them grow larger fruits
• What is the primary use of ethylene in fruit?

  To stimulate the ripening of fruit
• Why is controlling the ripening process of fruit important?

  It allows for better transport and sale
• How do farmers use ethylene during fruit transport?

  They expose fruit to ethylene to ripen
• How does ethylene work at the cellular level?

  It stimulates an enzyme that causes ripening
• What are the commercial applications of auxin, gibberellin, and ethylene?

  • Auxin:
  • Stimulates growth in tissue culture
  • Promotes rooting in cuttings
  • Acts as a selective weed killer
  • Gibberellin:
  • Controls seed dormancy
  • Induces flowering
  • Promotes larger fruit growth
  • Ethylene:
  • Stimulates fruit ripening
  • Controls ripening during transport