Chapter 06 Control and Coordination Questions-02
Questions
1. What are plant hormones?
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Answer
Plant hormones are the fluids which are secreted within the plant also known as phytohormones. Plant hormones regulate the growth and development of the plant. Examples of plant hormones are auxin, gibberellins etc.
2. How is the movement of leaves of the sensitive plant different from the movement of a shoot towards light?
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Answer
The movements of the leaves of the sensitive plant are touch sensitive and independent of growth while the movement of the shoot towards light is growth related and known as phototropism.
3. Give an example of a plant hormone that promotes growth.
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Answer
Auxin
4. How do auxins promote the growth of a tendril around a support?
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Answer
When tendrils come in contact with any support, the part of the tendril in contact with the object does not grow as rapidly as the part of the tendril away from the object. This is caused by the action of auxin hormone. Less auxin occurs on the side of contact as compared to the free side as a result, auxin promotes growth on the free side and the tendrils coil around the support.
5. Design an experiment to demonstrate hydrotropism.
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Answer
Take two small beakers and label them as A and B. Fill beaker A with water. Now make a cylindrical-shaped roll from a filter paper and keep it as a bridge between beaker $A$ and beaker $B$, as shown in the figure. Attach few germinating seeds in the middle of the filter paper bridge. Now, cover the entire set-up with a transparent plastic container so that the moisture is retained.
Observation:
The roots of the germinating seeds will grow towards beaker A.
This experiment demonstrates the phenomenon of hydrotropism.
