Answer: Shorter than a critical length.
- A Shorter than a critical length
- B Longer than a critical length
- C Exactly twelve hours long
- D Of no importance at all
Correct answer: A. Shorter than a critical length
Explanation: Long-day plants flower when the dark period is shorter than a critical length (i.e. days are long enough).
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.