Answer: tips of roots and shoots.
- A tips of roots and shoots
- B the middle of the old stem
- C the fully grown old leaves
- D the outer woody bark
Correct answer: A. tips of roots and shoots
Explanation: Apical meristems at root and shoot tips drive primary growth.
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.