Answer: Phototropism.
- A Geotropism
- B Thigmotropism
- C Hydrotropism
- D Phototropism
Correct answer: D. Phototropism
Explanation: Phototropism is the directional growth response of a plant organ toward or away from a light source, with shoots typically showing positive phototropism.
Geometric growth (where both daughter cells keep dividing) produces this classic S-shaped curve: a slow lag phase, a rapid exponential phase, and a levelling-off stationary phase as nutrients or space become limiting - the same fundamental pattern seen in population growth.
Concept context
Phases of plant growth, the five classical plant hormones plus newer ones, photoperiodism, vernalization, and seed dormancy.