Answer: The leaf.
- A The root tip
- B The leaf
- C The flower bud
- D The stem apex
Correct answer: B. The leaf
Explanation: Leaves perceive the photoperiod and produce a flowering signal (florigen) that moves to the shoot tip.
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.