10.1.10 Auxins

• Auxins


  The growth hormone in plants
• Auxins


  • Cause cell growth
  • Increase in size of cells or increase in dry mass
• How auxin causes growth


  Auxins stimulate plants to grow in relation to light (phototropism) or gravity (gravitropism)
• Phototropism


  Growth in relation to light
• Gravitropism


  Growth in relation to gravity
• How gravitropism causes shoots to grow against gravity


  Shoots will always try to grow upwards, against gravity and roots will try to grow downwards (with gravity)

  
• Clinostat


  A piece of apparatus that you can attach a plant to and it can turn, to investigate the effect of gravity on plant shoot or root growth

  
• If the light is unilateral (from one side), auxin stimulates growth towards the light