Question

67. In trees the growth rings represent : (A) Secondary phloem (B) Cork-cambium Secondary xylem o (D) Primary xylem​

Answer 1

Answer:

Secondary xylem

Explanation:

A growth layer in secondary xylem seen in a cross section of a woody stem or branch. A layer of wood formed in a plant during a single period of growth. Growth rings are visible as concentric circles of varying width when a tree is cut crosswise. They represent layers of cells produced by the tissue known as vascular cambium. Most growth rings reflect a full year's growth and are called as annual rings. But abrupt changes in the environment, especially in the availability of water, can cause a plant to produce more than one growth ring in a year. So, in trees the growth rings represents secondary xylem and not primary xylem, secondary phloem and cambrium.

Answer 2

Answer:

The cork cambium also is a secondary meristem, containing meristematic cells. The cork cambium forms a major portion of the bark of woody plants. The secondary phloem also is part of the bark, but of course phloem is produced by the vascular cambium.