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In old trees the greater part of secondary xylem is dark brown and resistant to insect attack due to:
(a) secretion of secondary metabolities and their deposition in the lumen of vessels.
(b) deposition of organic compounds like tannins and resins in the central layers of stem.
(c) deposition of suberin and aromatic substances in the outer layer of stem.
(d) deposition of tannins, gum, resin and aromatic substances in the peripheral layers of stem.
(e) presence of parenchyma cells, functionally active xylem elements and essential oils.
Choose the correct answer from the options given below:
(a) secretion of secondary metabolities and their deposition in the lumen of vessels.
(b) deposition of organic compounds like tannins and resins in the central layers of stem.
(c) deposition of suberin and aromatic substances in the outer layer of stem.
(d) deposition of tannins, gum, resin and aromatic substances in the peripheral layers of stem.
(e) presence of parenchyma cells, functionally active xylem elements and essential oils.
Choose the correct answer from the options given below:
- a)(c) and (d) Only
- b)(d) and (e) Only
- c)(b) and (d) Only
- d)(a) and (b) Only
Correct answer is option 'D'. Can you explain this answer?
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In old trees the greater part of secondary xylem is dark brown and res...
In old trees, the greater part of secondary xylem is dark brown and resistant to insect attack due to the secretion of secondary metabolites and their deposition in the lumen of vessels (option a) and the deposition of organic compounds such as tannins and resins in the central layers of the stem (option b). These substances help protect the tree from damage by insects and other pests.
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In old trees the greater part of secondary xylem is dark brown and res...
The correct answer is option (d) - deposition of tannins, gum, resin, and aromatic substances in the peripheral layers of the stem.
Explanation:
Old trees develop secondary xylem, which is responsible for providing mechanical support and transporting water and nutrients throughout the plant. The secondary xylem is also known as wood and is composed of various types of cells, including vessel elements, fibers, and parenchyma cells.
The greater part of secondary xylem in old trees is dark brown and resistant to insect attack. This resistance is due to the deposition of certain substances in the peripheral layers of the stem. Let's look at each option to understand why they are incorrect or correct:
(a) Secretion of secondary metabolites and their deposition in the lumen of vessels: This option is incorrect because the secondary xylem does not secrete secondary metabolites into the lumen of vessels. Secondary metabolites may be produced by other parts of the plant for various purposes, but they are not responsible for the resistance seen in the secondary xylem of old trees.
(b) Deposition of organic compounds like tannins and resins in the central layers of the stem: This option is incorrect because the deposition of tannins and resins occurs in the peripheral layers of the stem, not the central layers.
(c) Deposition of suberin and aromatic substances in the outer layer of the stem: This option is incorrect because suberin and aromatic substances are not specifically responsible for the resistance seen in the secondary xylem of old trees. Suberin is a waxy substance found in the cork cells of the bark, not the secondary xylem.
(d) Deposition of tannins, gum, resin, and aromatic substances in the peripheral layers of the stem: This option is correct. The dark brown color and resistance to insect attack in the secondary xylem of old trees are primarily due to the deposition of tannins, gum, resin, and aromatic substances in the peripheral layers of the stem. These substances act as natural defenses against insects, preventing them from damaging the wood.
(e) Presence of parenchyma cells, functionally active xylem elements, and essential oils: This option is incorrect because while parenchyma cells and functionally active xylem elements are present in the secondary xylem, they are not directly responsible for the resistance to insect attack. Essential oils, on the other hand, are not typically found in the secondary xylem.
In conclusion, the correct answer is option (d) - deposition of tannins, gum, resin, and aromatic substances in the peripheral layers of the stem. These substances provide the dark brown color and resistance to insect attack in the secondary xylem of old trees.
Explanation:
Old trees develop secondary xylem, which is responsible for providing mechanical support and transporting water and nutrients throughout the plant. The secondary xylem is also known as wood and is composed of various types of cells, including vessel elements, fibers, and parenchyma cells.
The greater part of secondary xylem in old trees is dark brown and resistant to insect attack. This resistance is due to the deposition of certain substances in the peripheral layers of the stem. Let's look at each option to understand why they are incorrect or correct:
(a) Secretion of secondary metabolites and their deposition in the lumen of vessels: This option is incorrect because the secondary xylem does not secrete secondary metabolites into the lumen of vessels. Secondary metabolites may be produced by other parts of the plant for various purposes, but they are not responsible for the resistance seen in the secondary xylem of old trees.
(b) Deposition of organic compounds like tannins and resins in the central layers of the stem: This option is incorrect because the deposition of tannins and resins occurs in the peripheral layers of the stem, not the central layers.
(c) Deposition of suberin and aromatic substances in the outer layer of the stem: This option is incorrect because suberin and aromatic substances are not specifically responsible for the resistance seen in the secondary xylem of old trees. Suberin is a waxy substance found in the cork cells of the bark, not the secondary xylem.
(d) Deposition of tannins, gum, resin, and aromatic substances in the peripheral layers of the stem: This option is correct. The dark brown color and resistance to insect attack in the secondary xylem of old trees are primarily due to the deposition of tannins, gum, resin, and aromatic substances in the peripheral layers of the stem. These substances act as natural defenses against insects, preventing them from damaging the wood.
(e) Presence of parenchyma cells, functionally active xylem elements, and essential oils: This option is incorrect because while parenchyma cells and functionally active xylem elements are present in the secondary xylem, they are not directly responsible for the resistance to insect attack. Essential oils, on the other hand, are not typically found in the secondary xylem.
In conclusion, the correct answer is option (d) - deposition of tannins, gum, resin, and aromatic substances in the peripheral layers of the stem. These substances provide the dark brown color and resistance to insect attack in the secondary xylem of old trees.
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In old trees the greater part of secondary xylem is dark brown and resistant to insect attack due to:(a) secretion of secondary metabolities and their deposition in the lumen of vessels.(b) deposition of organic compounds like tannins and resins in the central layers of stem.(c) deposition of suberin and aromatic substances in the outer layer of stem.(d) deposition of tannins, gum, resin and aromatic substances in the peripheral layers of stem.(e) presence of parenchyma cells, functionally active xylem elements and essential oils.Choose the correct answer from the options given below:a)(c) and (d) Onlyb)(d) and (e) Onlyc)(b) and (d) Onlyd)(a) and (b) OnlyCorrect answer is option 'D'. Can you explain this answer?
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In old trees the greater part of secondary xylem is dark brown and resistant to insect attack due to:(a) secretion of secondary metabolities and their deposition in the lumen of vessels.(b) deposition of organic compounds like tannins and resins in the central layers of stem.(c) deposition of suberin and aromatic substances in the outer layer of stem.(d) deposition of tannins, gum, resin and aromatic substances in the peripheral layers of stem.(e) presence of parenchyma cells, functionally active xylem elements and essential oils.Choose the correct answer from the options given below:a)(c) and (d) Onlyb)(d) and (e) Onlyc)(b) and (d) Onlyd)(a) and (b) OnlyCorrect answer is option 'D'. Can you explain this answer? for NEET 2024 is part of NEET preparation. The Question and answers have been prepared according to the NEET exam syllabus. Information about In old trees the greater part of secondary xylem is dark brown and resistant to insect attack due to:(a) secretion of secondary metabolities and their deposition in the lumen of vessels.(b) deposition of organic compounds like tannins and resins in the central layers of stem.(c) deposition of suberin and aromatic substances in the outer layer of stem.(d) deposition of tannins, gum, resin and aromatic substances in the peripheral layers of stem.(e) presence of parenchyma cells, functionally active xylem elements and essential oils.Choose the correct answer from the options given below:a)(c) and (d) Onlyb)(d) and (e) Onlyc)(b) and (d) Onlyd)(a) and (b) OnlyCorrect answer is option 'D'. Can you explain this answer? covers all topics & solutions for NEET 2024 Exam. Find important definitions, questions, meanings, examples, exercises and tests below for In old trees the greater part of secondary xylem is dark brown and resistant to insect attack due to:(a) secretion of secondary metabolities and their deposition in the lumen of vessels.(b) deposition of organic compounds like tannins and resins in the central layers of stem.(c) deposition of suberin and aromatic substances in the outer layer of stem.(d) deposition of tannins, gum, resin and aromatic substances in the peripheral layers of stem.(e) presence of parenchyma cells, functionally active xylem elements and essential oils.Choose the correct answer from the options given below:a)(c) and (d) Onlyb)(d) and (e) Onlyc)(b) and (d) Onlyd)(a) and (b) OnlyCorrect answer is option 'D'. Can you explain this answer?.
In old trees the greater part of secondary xylem is dark brown and resistant to insect attack due to:(a) secretion of secondary metabolities and their deposition in the lumen of vessels.(b) deposition of organic compounds like tannins and resins in the central layers of stem.(c) deposition of suberin and aromatic substances in the outer layer of stem.(d) deposition of tannins, gum, resin and aromatic substances in the peripheral layers of stem.(e) presence of parenchyma cells, functionally active xylem elements and essential oils.Choose the correct answer from the options given below:a)(c) and (d) Onlyb)(d) and (e) Onlyc)(b) and (d) Onlyd)(a) and (b) OnlyCorrect answer is option 'D'. Can you explain this answer? for NEET 2024 is part of NEET preparation. The Question and answers have been prepared according to the NEET exam syllabus. Information about In old trees the greater part of secondary xylem is dark brown and resistant to insect attack due to:(a) secretion of secondary metabolities and their deposition in the lumen of vessels.(b) deposition of organic compounds like tannins and resins in the central layers of stem.(c) deposition of suberin and aromatic substances in the outer layer of stem.(d) deposition of tannins, gum, resin and aromatic substances in the peripheral layers of stem.(e) presence of parenchyma cells, functionally active xylem elements and essential oils.Choose the correct answer from the options given below:a)(c) and (d) Onlyb)(d) and (e) Onlyc)(b) and (d) Onlyd)(a) and (b) OnlyCorrect answer is option 'D'. Can you explain this answer? covers all topics & solutions for NEET 2024 Exam. Find important definitions, questions, meanings, examples, exercises and tests below for In old trees the greater part of secondary xylem is dark brown and resistant to insect attack due to:(a) secretion of secondary metabolities and their deposition in the lumen of vessels.(b) deposition of organic compounds like tannins and resins in the central layers of stem.(c) deposition of suberin and aromatic substances in the outer layer of stem.(d) deposition of tannins, gum, resin and aromatic substances in the peripheral layers of stem.(e) presence of parenchyma cells, functionally active xylem elements and essential oils.Choose the correct answer from the options given below:a)(c) and (d) Onlyb)(d) and (e) Onlyc)(b) and (d) Onlyd)(a) and (b) OnlyCorrect answer is option 'D'. Can you explain this answer?.
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ample number of questions to practice In old trees the greater part of secondary xylem is dark brown and resistant to insect attack due to:(a) secretion of secondary metabolities and their deposition in the lumen of vessels.(b) deposition of organic compounds like tannins and resins in the central layers of stem.(c) deposition of suberin and aromatic substances in the outer layer of stem.(d) deposition of tannins, gum, resin and aromatic substances in the peripheral layers of stem.(e) presence of parenchyma cells, functionally active xylem elements and essential oils.Choose the correct answer from the options given below:a)(c) and (d) Onlyb)(d) and (e) Onlyc)(b) and (d) Onlyd)(a) and (b) OnlyCorrect answer is option 'D'. Can you explain this answer? tests, examples and also practice NEET tests.
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