IAA

• WHAT IS AN EXAMPLE OF A PLANT GROWTH FACTOR?

  IAA
• WHAT IS IAA?

  indoleacetic acid
• WHAT IS IAA?

  type of auxin
• WHAT DOES IAA DO?

  control elongation of plant cell walls
• WHAT IS THE EFFECT IAA HAS IN SHOOTS?

  increases cell elongation
• WHAT IS THE EFFECT IAA HAS IN ROOTS?

  inhibits cell elongation
• WHAT DOES IAA DO IN ELONGATION?

  • IAA increases plasticity of the cell wall
  • however only in young cell walls
• WHAT IS PLASTICITY?

  ability to stretch
• WHY DOES IAA ONLY HAVE AN EFFECT ON YOUNG CELL WALLS?

  they develop rigidity as they mature
• HOW DO IAA'S INCREASE CELL PLASTICITY?

  Acid Growth Hypothesis
• WHAT IS THE ACID GROWTH HYPOTHESIS?

  active transport of H+ ions from cytoplasm into spaces in the cell wall causing the cell to elongate by expansion