Question

The increase in length of plant body is due to:

• A. Secondary meristem
• B. Lateral meristem
• C. Apical meristem
• D. Cork cambium Correct Answer: (C) Apical meristem

Hint:

To easily remember the direction of plant growth on your exams, link the anatomical positions to their physical directions: - Apex / Apical $\implies$ Think of the "Apex" or top peak, which drives Vertical Length. - Lateral $\implies$ Think of the "Latitude" or sides, which drives Horizontal Width/Girth.

Answer 1

The Correct Option is C

Step 1: Understanding the Concept:
Meristematic tissues are classified based on their specific position within the plant body and the direction of growth they promote. This structural distribution creates a division of labor: one group drives upward and downward vertical extension (primary growth), while another group drives outward horizontal thickening (secondary growth).

Step 2: Detailed Explanation:
Let's analyze the functions of the different meristems listed: - (A) Secondary meristem & (B) Lateral meristem: These terms refer to tissues located along the lateral sides of stems and roots, running parallel to the organs. They divide periclinally to add thickness, girth, or diameter to the plant axis. - (C) Apical meristem: These are located at the absolute tips or apexes of the growing shoots (Shoot Apical Meristem - SAM) and roots (Root Apical Meristem - RAM). The active division of these cells drives the elongation of the plant along its main vertical axis, directly resulting in an increase in length. This vertical extension constitutes the plant's primary growth. - (D) Cork cambium: A specific type of lateral secondary meristem that replaces the outer damaged epidermis with protective cork tissue as the plant grows wider. Thus, the elongation or increase in length is explicitly driven by the apical meristem. This matches option (C).

Step 3: Final Answer:
The increase in length of the plant body is due to the Apical meristem.