Question

The annual rings in a hundred-year-old tree will show
A. The same number of rings from the base of the trunk to the terminal region of branches.
B. An irregular number of rings that increase or decrease sporadically along its length.
C. About one hundred rings at the base with numbers gradually decreasing towards the apex.
D. About one hundred rings at the base and twenty-five at its apex.

Answer 1

Annual rings are additional layers of wood added each year in the stem or root of trees or shrubs. The annual rings are also known as growth rings. The growth ring of a tree can be seen in a cross-section of its trunk.

Complete answer:
These rings are said to be formed due to secondary growth.
This secondary growth occurs in dicot trees which occur due to vascular cambium which is a meristem tissue.
Due to many physiological and environmental factors like the seasonal variation in the growth speed of a tree two types of rings are formed.
During the spring season the rate of activity of vascular cambium is more therefore the trunk has larger and wider xylem cells this is called springwood or early wood. Whereas in winter the trunk has less activity of vascular cambium therefore the wood formed has narrower and smaller xylem cells, this is called autumn wood or latewood.
This variation creates two sets of rings called Annual rings or growth rings.
The age of the tree can be determined by counting these rings at the base. The rings tend to moderately decrease towards the apex.
Therefore in a hundred-year-old tree, the total number of rings would be a hundred.

So, the correct answer is C) About one hundred rings at the base with the number gradually decreasing towards the apex.

Note: Dendrochronology or growth ring analysis is a branch of science that deals with finding the age of a tree through its number of annual rings. These rings also give us information about climates of the past that might have occurred.