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प्रश्न
Why is the closing of a dandelion flower at dusk (when it gets dark) not a tropism?
उत्तर
The closing of a dandelion flower at dusk is not a tropism because it is a non-directional movement in response to the intensity of light. On the contrary, tropic movement is the movement of plant parts towards the light. It does not depend upon the intensity of light.
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संबंधित प्रश्न
What does a tendril do in response to the touch of a support? What is this phenomenon known as?
What is the difference between photonasty and thigmonasty?
How does phototropism occur in a plant stem (or shoot)? Explain with the help of labelled diagrams.
The bending of the stem of a plant towards a source of light is caused by the action of a phytohormone known as :
(a) abscisic acid
(b) auxin
(c) gibberellins
(d) cytokinin
Which of the following are not tropisms?
(i) growing of pollen tube in response to a sugary substance
(ii) folding up of leaves of sensitive plant in response to touch
(iii) winding of tendril around a support in response to touch
(iv) opening up of the leaves of a daisy flower in response to light
(a) (i) and (ii) (b) (ii) and (iii) (c) (i) and (iv) (d) (ii) and (iv)
A potted plant having straight parts A and B was placed horizontally on its side as shown in Figure (i). After a few days, it was observed that parts A and B of the plant acquired new positions as shown in Figure (ii).
- Name the phenomenon exhibited by the position of plant parts A and B in Figure (ii).
- Name the stimulus (other than sunlight) which causes plant part A to grow and bend upwards, and plant part B to bend downwards.
The shoot system grows upward in response to ______.
The opening and closing of the Moonflower is not a tropism because the movement in this is ______.
Analogy:
Hydrotropism: Response towards water:: Phototropism: ______.
Define the following term:
Tropism
