Plant Hormones

• Plants rely entirely on Hormones to respond to their environments, to increase their chances of survival
• Once Auxins are produced in the tips

  • They dissolve in the solution of the plant cells
  • And diffuse backwards along the shoot/root

  Shoots Stimulate growth AND Roots Inhibit Growth

  A) Stimulate

  B) Inhibit

  
• SHOOTS are:

  • POSITIVELY Phototropic - The Auxins accumulate in the shade (the right) and makes the cells elongate faster on the shaded side

  The difference in Growth rate causes the shoot to curve around towards the light

  
• SHOOTS are:

  • NEGATIVELY Geotropic - The Auxins on the lower side cause this side to grow faster, bending the shoot upwards away from gravity

  
• ROOTS are

  • POSITIVELY Geotropic - The Auxins accumulating on the lower side of the root inhibit growth, so the upper side will elongate at a faster rate

  This bends the roots downwards, towards Gravity