Question

Youngest heartwood is found.
(A) In the centre
(B) Just outside the sapwood
(C) Just inner to sapwood
(D) Just outside the primary xylem

Answer 1

Hint: In nature, plants are divided into two groups based on the presence of their wood i.e. sapwood and heartwood. The exterior part of the plant stem is known as sapwood and the interior wood is often called heartwood.

Complete step by step answer:
Let’s discuss the question and find the proper answer.
- Heartwood is also known as duramen. It presents at the inner portion of the stem and contains the secondary xylem. These are mainly dark in colour and often hard. It is often found near to the pith. From here new xylem and phloems are made in future. The heartwoods are made up of mainly dead and strong primary xylem.
- Sapwood is also known as laburnum. The outer layers of sapwood remain soft and play an important role in water conduction. Cells are light in colour. Loosely arranged cells are found here. It contains the secondary xylem that is mainly living and functional.
- The xylem that is formed in apical meristem during the growth of procambium is called primary xylem. Whereas secondary xylem is formed during the secondary growth of plant tissue.
Hence option C: Just inner to sapwood is the correct answer.

Note: In heartwood, most of the cells are comparatively old and mostly dead while in sapwood, most of the cells are comparatively younger and many of them are alive.