Karnataka Secondary Education Examination BoardKarnataka SSLC
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Coordination in Plants - Immediate Response to Stimulus

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Control and Coordination in plants:-

Coordination is the ability to use different parts of the plant together, smoothly and efficiently. In plants, coordination is due to the result of a chemical system, wherein plant hormones or phytohormones have a major role.

Movement in plants

Plants exhibit two types of movements.

  1. Growth-dependent movements called the Tropic Movements. ( towards or away from a stimulus)
  2. Non-growth dependent movements called the Nastic Movements. ( independent of stimulus)

Tropic movements

These can be classified again into 5 types. They are:

  • Phototropism (light)
  • Geotropism (gravity)
  • Hydrotropism (water )
  • Chemotropism (chemicals)
  • Thigmotropism (touch)
  1. Phototropism – It is the movement of plants in response to light. The shoot system of a plant exhibits this characteristic. The shoot moves towards the light.
  2. Geotropism – It is the movement of a plant part towards the soil. This is a characteristic of the root system. The roots always move in the direction of the earth’s gravity.
  3. Hydrotropism– It is the movement of a plant towards the water. The stimulus here is water.
  4. Chemotropism – It is the movement of plants in response to a chemical stimulus. A classic example of this type of movement is the growth of the pollen tube towards the ovule, during fertilization, in a flower.
  5. Thigmotropism – It is a directional movement in plants in response to touch. For e.g. the plant tendrils climb around any support which they touch.

Nastic Movements

Nastic movements in plants are not directional movements. They are not dependent on stimulus and are growth independent. For example, the leaves of a touch me not plant (Mimosa pudica), fold up immediately when touched. These kinds of changes occur due to the changes in the amount of water in the leaves. Depending on the quantity, they either swell up or shrink.

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Shaalaa.com | Type of tropic movement


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Type of tropic movement [00:11:16]
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