Chapter 39: Plant Hormones

Question 1

Auxin (IAA)

Answer 1

• Plant Hormone
• Produced in:
  - shoot apical meristems
  - young leaves
• Functions:
  - cell elongation
  - root formation
  - secondary growth
  - fruit growth
  - alters gene expression

Question 2

Cytokinins

Answer 2

• Class of related plant hormones
• Primarily synthesized in the roots
• Functions:
  - retard aging
  - works with auxin to stimulate cell division
  - influence the pathway of differentiation
  - control apical dominance

Question 3

Gibberellins (GA)

Answer 3

• -Class of related plant hormones
• Produced in:
  - Meristems of apical buds & roots
  - young leaves
  - developing seeds
• Functions:
  - stimulate growth in stem and leaves
  - trigger the germination of seeds
  - trigger breaking of bud dormancy
  - works with auxin to stimulate fruit development

Question 4

Abscisic Acid (ABA)

Answer 4

• Plant hormone
• Produced in every major organ and living tissue
• Functions:
  - slows growth
  - promotes seed dormancy
  - facilitates drought tolerance
  - promotes stomatal closure during stress

Question 5

Ethylene

Answer 5

• Gaseous plant hormone
• Produced during:
  - senescence
  - leaf abscission
  - ripening of fruits
  - wounding/stress
• Functions:
  - Promotes ripening of fruit
  - Promotes leaf abscission
  - Inhibits stem elongation

Question 6

Brassinosteroids

Answer 6

• Steroid plant hormone
• Produced in all plant tissue
• Functions:
  - induces cell elongation
  - retards leaf abscission
  - promotes xylem differentiation