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Topic: Plant tissues and anatomy of root, stem, leaf· Structural Organisation in Animals and Plants

In old trees the greater part of seco[...] dark brown and resistant to insect attack due [...](a) secretion of secondary metabolites and their deposition in the lumen of vessels.(b) deposition of organic compounds like tannins and resins in the centr…

In old trees the greater part of seco[...] dark brown and resistant to insect attack due [...]

(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

1 answer

Best answer

Answer: 2. (a) and (b) Only

Heartwood is dark brown and resistant to insects and microbes because of chemical deposits in the central, old xylem.

  • (a) Secondary metabolites get deposited in the lumen of vessels: correct.
  • (b) Tannins, resins and other organic compounds are deposited in the central layers: correct.
  • (c), (d) These describe outer or peripheral layers, which is the sapwood region, not the dark heartwood.
  • (e) Functionally active xylem and parenchyma describe sapwood.

So (a) and (b) only.

Doubtly AI · 30 Oct 2026 AI-generated · not yet verified Report
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