As the tree grows outward from the pith, the inner cells become inactive and turn into which part of the wood?

As the tree grows outward from the pith, the inner cells become inactive and turn into which part of the wood?

• A. Sapwood
• B. Pith
• C. Heartwood
• D. Bark

Answer: (C)

As trees grow, new layers of xylem are added outward by the cambium, while the oldest xylem in the center stops functioning for water transport. Those inner cells become inactive and, over time, are impregnated with extractives such as tannins and resins, which darken and harden them into heartwood. Heartwood remains structurally strong and helps resist decay, even though it no longer conducts water. The outer, active xylem near the surface is sapwood and handles water transport, while the central pith is a different tissue and is not the part that becomes heartwood.

As trees grow, new layers of xylem are added outward by the cambium, while the oldest xylem in the center stops functioning for water transport. Those inner cells become inactive and, over time, are impregnated with extractives such as tannins and resins, which darken and harden them into heartwood. Heartwood remains structurally strong and helps resist decay, even though it no longer conducts water. The outer, active xylem near the surface is sapwood and handles water transport, while the central pith is a different tissue and is not the part that becomes heartwood.