Class 10 Biology Control and Coordination Hormonal system on plants

Hormonal system on plants

  • Different kinds of hormones are responsible for growth, development and response to the stimulus.
  • Auxin- i) A plant hormone, synthesized at the shoot tips and helps the cells to grow longer

    ii)When plants detect light auxins are synthesized and when light comes from one side of the shoot auxins diffuse towards the shaded side of the shoot.

   iii) Concentration of auxin in the shaded side stimulates the cells to grow longer on the shaded side of the shoot and thus plants appear to bend towards light.

  • Gibberellins- Plant hormone gibberellins help in the growth of stem.

Fig. growth of stem  

  • Cytokinins– This hormone promotes cell division and concentration is high in fruits and seeds.
  • Abscisic acid- Unlikeauxin, gibberellins, cytokinis which promote growth, abscisic acid stops growth and causes wilting of leaves.

Fig. wilting of leaf

 

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