alleryWhich substance makes xylem walls rigid and waterproof?
ACellulose in thin primary cell walls
BLignin deposited on the inner walls
CSuberin coating cork cells of bark
DChitin used in fungal cell walls
Answer & Solution
Correct answer: B. Lignin deposited on the inner walls
1. The chapter notes xylem cells are dead and highly thick-walled.
2. The thickening material is lignin, a tough waterproof polymer.
3. Cellulose only forms thin primary walls.
4. So the answer is lignin.
_Source: Selina Concise Biology Class 8, Ch on Transport in Plants (Mistral OCR'd PDF), Xylem Structure_
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