Non-directional movement of plants in response to external stimuli is called:a)Nastic Movementb)Tropismc)Growthd)RipeningCorrect answer is option 'A'. Can you explain this answer?

Question

Answer

The movement of a plant part in response to an external stimulus in which the direction of response is not determined by the direction of stimulus is known as Nastic movement. It is also known as Nasties. The stimuli may be classified as light, heat, touch or contact, etc...

Answer

Nastic movement:;

Non directional movement of plant in response to an external stimulus for example ,, thigmonasty,photonasty

Answer

Non-directional movement of plants in response to external stimuli is called Nastic Movement.

Nastic movements, also known as nastic responses, are non-directional movements in plants that occur in response to external stimuli such as light, temperature, touch, and gravity. Unlike tropisms, which involve directional growth towards or away from a stimulus, nastic movements are independent of the direction of the stimulus.

There are several types of nastic movements that plants can exhibit:

1. Photonastic movements: These movements are in response to light. For example, the opening and closing of flowers in response to day and night cycles is a photonastic movement called nyctinasty. The leaves of certain plants also show photonastic movements, such as the folding up of leaves in response to darkness.

2. Thigmonastic movements: Thigmonasty refers to movements in response to touch or mechanical stimuli. Examples include the rapid closing of the leaves of the Venus flytrap when triggered by an insect or the movement of the sensitive plant's leaves when touched.

3. Thermonastic movements: These movements are in response to temperature changes. For instance, certain flowers open or close in response to changes in temperature.

4. Seismonastic movements: Seismonasty is the response to vibrations or mechanical disturbances. The movement of mimosa leaves when they are touched or agitated is an example of seismonastic movement.

5. Nyctinastic movements: Nyctinasty is the response to day and night cycles. Flowers that open during the day and close at night exhibit nyctinastic movements.

These nastic movements are not growth-related but rather involve changes in turgor pressure within the cells of the plant. The changes in turgor pressure cause specific movements in response to the stimulus.

In conclusion, non-directional movement of plants in response to external stimuli is referred to as nastic movement. These movements include photonastic, thigmonastic, thermonastic, seismonastic, and nyctinastic movements. They are not growth-related but involve changes in turgor pressure within the cells of the plant.

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