Select from the following the correct statement about tropic movement in plants :
Generated by claude-sonnet-4-6 · 2026-06-15 06:50 · grounding rag
Model Answer
(d) It is a growth related movement.
Tropic movements are directional growth movements in plants in response to an external stimulus (light, gravity, water, etc.), where the direction of movement depends on the direction of the stimulus.
Source: Chapter 6, Section 6.2 – Coordination in Plants / Movement Due to Growth
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Explanation
- Option (a) is wrong — touch causes nastic/seismonastic movement (e.g., Mimosa), not tropic movement; temperature is not the primary stimulus for tropism.
- Option (b) is wrong — tropic movement does depend on the direction of stimulus (that is what makes it "directional").
- Option (c) is wrong — both roots and stems show tropic movements (e.g., shoots bend towards light, roots away from light).
- Option (d) is correct — the textbook explicitly states: "The directional movement of a seedling is caused by growth" and "these directional, or tropic, movements" are growth-related.
Key term to remember: Tropic movements = directional + growth-dependent + stimulus-directed.