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Question
Assertion :The greater part of secondary xylem is lighter in colour and consists of dead elements with highly lignified walls and is called heartwood. Reason: The peripheral region of the secondary xylem is dark brown in colour and is called sapwood.
Assertion :The greater part of secondary xylem is lighter in colour and consists of dead elements with highly lignified walls and is called heartwood. Reason: The peripheral region of the secondary xylem is dark brown in colour and is called sapwood.
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Solution
The correct option is D Both Assertion and Reason are incorrect
In old trees, the greater part of secondary xylem is dark brown due to deposition of organic compounds like tannins, resins, oils, gums, aromatic substances and essential oils in the central or innermost layers of the stem. This region comprises dead elements with highly lignified walls and they are non conducting these are called heartwood. The peripheral region of the secondary xylem is lighter in colour and porous which conducts water, is known as the sapwood.Hence correct option is (D)
In old trees, the greater part of secondary xylem is dark brown due to deposition of organic compounds like tannins, resins, oils, gums, aromatic substances and essential oils in the central or innermost layers of the stem. This region comprises dead elements with highly lignified walls and they are non conducting these are called heartwood. The peripheral region of the secondary xylem is lighter in colour and porous which conducts water, is known as the sapwood.
Hence correct option is (D)
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