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🔬 Biology  ·  Plant Growth and Development  ·  NEET

ABA (Abscisic acid) causes:

Answer: Stomatal closure and dormancy.

  • A Rapid stem elongation and internode growth
  • B Triggering of seed germination processes
  • C Stomatal closure and dormancy
  • D Acceleration of fruit ripening and softening

Correct answer: C. Stomatal closure and dormancy

Explanation: ABA is a stress hormone. It causes stomatal closure (water stress) and promotes seed/bud dormancy. Known as stress hormone.

Geometric Growth: the Sigmoid Curvetimegrowthlag phaselog/exponential phasestationary phaseGrowth starts slow, accelerates rapidly, then plateaus as resources become limiting

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.

Read the full Plant Growth and Development notes →