Archive
16th of September 2015
Biology
Q:

please explain with the help of a diagram the effect of auxins in different parts of a plant.

Sunil Kumar Ayyappan Santhamma - CBSE - Class VI

Wednesday, September 16, 2015 at 18:40:PM

A:

Hi Sunil,

Auxins are found in tips of the shoots and roots but can diffuse to other areas.

The hormones affect the rate of elongation of plant cells.

Effect of auxins:

  • Shoot cells to grow more quickly
  • Root cells to grow less quickly

Phototropism

  • Auxins diffuse to the shaded areas of shoots and roots.
  • In shoots the high concentration of auxin causes the shaded shoot cells to grow more quickly.
  • The result is a shoot that bends towards the light.
  • In roots the high concentration of auxin causes the shaded cells to grow more slowly.
  • The result is a root that bends away from the light.

Gravitropism

  • Auxins are affected by gravity.
  • In horizontal shoots there is a higher concentration of auxin at the bottom.
  • This causes the bottom cells to grow more quickly, pushing the shoot up against gravity.
  • In horizontal roots, there is also a higher concentration of auxin at the bottom.
  • This causes the bottom cells to grow less quickly than the top cells, pushing the root into the ground.

Wednesday, September 16, 2015 at 18:54:PM