Question

How many shoot apical meristems are likely to be present in a twig of a plant possessing 4 branches and 26 leaves?
a. 26
b. 1
c. 5
d. 30

Answer 1

Hint: Meristems are specialized areas in the plant body that possess meristematic tissue. These areas exhibit active cell division as the cells present in them keep on diving to form other cells. Meristems are classified into three categories based on their position in the plat body, namely Apical meristem, Intercalary meristem, and Lateral meristem.

Complete answer:
The meristems occupy different areas in the body of plants and depending upon this, they can be divided into:

> Apical meristem: These tissues are found at the apices or tips of stem, root, or branch. These are further two types, root apical meristem (occupies the tip of the root) and shoot apical meristem (occupies the tip of a shoot).

> Intercalary meristem: These meristems are intercalated in between the mature tissues (or permanent tissues). These are separated from the apex of the organ by mature tissues. Its activity adds to the length of the plant and its organs.

> Lateral meristem: These meristems are present along the lateral sides of mature regions of roots and shoots of many plants. These do not occur in all the plants. These are not present from the very beginning of the life of the plant and are a result of secondary growth in plants. Therefore, these are also referred to as secondary meristems.

Since the given plant possesses four branches, it implies that it has four apical meristems at the apex of each branch. In addition to this, the main plant axis will also possess an apical meristem at its apex. Therefore, this twig of a plant will have 5 apical meristems in total.

Hence, the correct answer is option (C).

Note: Meristems are also categorized based on their origin/order of appearance in the life of a plant. These are referred to as Primary and Secondary meristems. Primary meristems appear early in the life of a plant and contribute to the formation of the primary plant body whereas Secondary meristems appear later and are responsible for the formation of secondary tissues.