Nastic Movements


 
 
Concept Explanation
 

Nastic Movements

Quick Movements of Plants or Nastic Movement

Rapid movements are uncommon in plants, but some plants do display such movements in response to stimuli. Touch the tip of a sensitive plant (Mimosa pudica) gently. Only a few leaflets close. When you touch it roughly, all the leaflets close.

In Mimosa pudica (touch me not plant), the leaflets fold up quickly if any leaflet is touched. How does it happen? It happens because the touch triggers a sudden and rapid loss of water (turgor changes) from cells at the base of the leaflets. These movements of sensitive plants in response to touch are very quick. All quick movements are not so quick. For example, the leaves of many plants, including those of Mimosa pudica, remain open during day. When darkness falls, the leaves fold up. Many flowers open after sunrise and close after sunset. All these movements are directed neither towards nor away from the stimulus. Such movements are called Nastic Movements.

Types of Nastic Movements:

  • Photonasty (stimulus: light): Plants show sleep movements according to the day and night pattern of the sun. e.g. opening and closing of petals of Oxalis.
  • Thigmonasty (stimulus: touch or vibrations):  e.g. bending of tentacles in Drosera.
  • Thermonasty (stimulus: change in temperature): e.g.opening and closing of flower in Tulip
  • Seismonasty (stimulus: touch or the shock produced by touch): drooping of leaves in Mimosa pudica (touch me not) plant.
  • Sample Questions
    (More Questions for each concept available in Login)
    Question : 1

    In  ____________________, the leaflets fold up quickly if any leaflet is touched.

    Right Option : A
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    Explanation
    Question : 2

    Nastic response resulting from contact or mechanical disturbance is known as ____________

    Right Option : D
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    Explanation
    Question : 3

    Which of the following in an example of nastic movement in plants?

    Right Option : C
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    Explanation
     
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