In old trees the greater part of secondary xylem is dark brown and resistant to insect attack due to :

a. secretion of secondary metabolites 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
1. (b) and (d) Only
2. (a) and (b) Only
3. (c) and (d) Only
4. (d) and (e) Only

Subtopic:  Types of Wood (OLD NCERT) |
 58%
From NCERT
NEET - 2022
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NEET 2023 - Target Batch - Aryan Raj Singh
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NEET 2023 - Target Batch - Aryan Raj Singh