Question

Annual rings are the bands of
a. Secondary cortex and cork
b. All secondary vascular tissue
c. Secondary xylem and xylem rays.
d. Secondary phloem and medullary rays.

Answer 1

Hint: A tree ring is a layer of wood produced during the one tree's growing season. Each tree ring marks the distinguishable line between the dark latewood. The dark latewood grew at the end of the previous year. The pale early wood that grew at the start of this year. One annual earlywood composed of a ring of earlywood and a ring of latewood.

Complete answer:
> The activity of secondary xylem and xylem rays are responsible for the band of the annual ring. They form early and latewood during spring and autumn. This alternation of early and late wood is due to the decrease in the number of vessel elements and an increase in the number of tracheids. These annual rings can be seen as a circular ring in the cross-section of the stem. So option C is correct.

> The cork cambium is the outermost layer of the lateral meristem tissue capable of regeneration. Cork cambium, also called phellogen. Cork cambium is another meristematic tissue developed in the cortex region. Due to the activity of the cambium, the outer layers which are present such as cortex cells and epidermis, they get crushed. So option A is incorrect.

> The secondary vascular tissue is responsible for secondary growth. It arises from the vascular cambium. It is a layer of meristematic tissue situated between the primary xylem and primary phloem. So option B is incorrect.

> The secondary phloem is formed by the vascular cambium during secondary growth. The medullary rays are found as a circular structure. So option D is also incorrect.

Hence, the correct answer is option (C).

Note: Annual rings are also known as growth rings. These are concentric circles visible in cross-sections of woody stems or trunks. Each year the cambium layer showing the secondary growth produces a layer of xylem. As a result of it, the vessels of xylem become large and thin-walled in the spring and smaller and thick-walled in the summer. This, creating a contrast between the rings.