Answer: chemotropism.
- A chemotropism
- B phototropism
- C geotropism
- D thigmotropism
Correct answer: A. chemotropism
Explanation: The pollen tube grows toward chemical signals from the ovule - chemotropism.
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.