- A Heartwood is sometimes mistakenly thought to be the newer wood formed each season; sapwood the older wood near the bark
- B Heartwood is older, darker, non-conducting, impregnated with tannins; sapwood is younger, lighter, still conducts water
- C Both heartwood and sapwood are sometimes mistakenly thought to be functionally identical in conduction and support
- D Heartwood is sometimes mistakenly thought to be located within the outer bark layer; sapwood occupying the central stem region
Correct answer: B. Heartwood is older, darker, non-conducting, impregnated with tannins; sapwood is younger, lighter, still conducts water
Explanation: Heartwood (duramen): older, inner secondary xylem, dark due to tannins/resins/oils, dead, non-conducting, provides mechanical support. Sapwood (alburnum): outer secondary xylem, lighter, still conducts water. Heartwood is more durable for timber.
Concept context
Internal tissue organisation: meristems, permanent tissues (xylem, phloem, parenchyma), and secondary growth. Frequently tested in NEET.