Question

Which plant hormone is responsible for cell elongation?

• A. Cytokinin
• B. Gibberellin
• C. Auxin
• D. Abscisic acid

Hint:

Associate each major plant hormone with its primary functions:
- Auxins: Cell elongation, tropisms.
- Cytokinins: Cell division.
- Gibberellins: Stem elongation (especially in dwarfism), germination.
- Abscisic acid: Stress response, dormancy.
- Ethylene: Fruit ripening, senescence.

Answer 1

The Correct Option is C

Step 1: Understanding the Question:
The question asks to identify the specific plant hormone that plays a primary role in promoting cell elongation.

Step 3: Detailed Explanation:
- Auxin: Auxins are a class of plant hormones that are crucial for cell elongation (especially in stems and coleoptiles), apical dominance, tropisms (phototropism and gravitropism), and fruit development. They promote the loosening of cell walls, allowing cells to expand.
- Cytokinin: Cytokinins primarily promote cell division and differentiation, and delay senescence.
- Gibberellin: Gibberellins promote stem elongation (especially in dwarf plants), seed germination, and flowering. While they promote elongation, auxins are more directly linked to the initial cell wall plasticity for elongation.
- Abscisic acid (ABA): ABA is a stress hormone that primarily inhibits growth, promotes dormancy, and plays a role in stomatal closure.
Among the given options, auxin is most directly responsible for cell elongation.

Step 4: Final Answer:
Auxin is the plant hormone responsible for cell elongation.