Concept explainers
Introduction:
Phytochrome is a blue-green pigment present in the plants. It helps the plants to respond in the presence of red and far-red light.
Answer to Problem 1TYK
Correct answer:
The phytochrome is not involved in guard-cell opening.
Explanation of Solution
Explanation/Justification for the correct answer:
Option (d) is given that phytochrome is not involved in guard-cell opening. The opening and closing of the stomata is managed by the guard cells. In the presence of light, the guard cells pick up water from the environment through the process of osmosis, which makes them turgid. It is so because the inner walls are tough and rigid. These walls are pulled apart, thereby opening the pore. The phytochrome has no role in the opening or closing of the guard cells. Hence, Option (d) is correct.
Explanation for the incorrect answers:
Option (a) is given that phytochrome is not photoreversible. The phytochrome belongs to the class of photoreceptors, which is used by the plants in order to detect the light and change conformation. It is sensitive toward the light that is present in the red or far-red portion of the visible spectrum. The light absorption alters the shape of the photoreceptor pigment. Therefore, this switching behavior of the cells on the basis of light is known as photoreversibility. So, it is a wrong answer.
Option (b) is given that phytochrome’s function was not understood long before the protein itself was isolated. The function of the phytochrome, that is, its role in photoperiodism, was understood prior to the isolation of the protein. So, it is a wrong answer.
Option (c) is given that Pfr (phytochrome far-red) form of phytochrome does not activate the responses to red light. The photoreversibility was seen when a molecule named Pfr was exposed to the far-red light. The molecule absorbed the light leading to the conformational change in the shape of the molecule. Therefore, phytochrome is affected by the light. So, it is a wrong answer.
Hence, options (a), (b), and (c) are incorrect.
The pigment phytochrome helps the plants to respond to the red/far-red light and exhibits the property of photoreversibility, and the function of phytochrome was understood long before the protein was isolated. Phytochrome is not involved in the opening of the guard cells.
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Chapter 40 Solutions
Biological Science
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