Summary
Plant growth and development is the process of irreversible increase in size and organs through division and differentiation of meristematic cells, controlled by plant growth regulators like auxins, gibberellins, cytokinins, ethylene, and abscisic acid.
Class 11 Biology Chapter 13 covers plant growth—a permanent, measurable increase in size achieved through meristematic cell division in three phases: meristematic, elongation, and maturation. Growth follows arithmetic or geometric patterns and requires water, oxygen, nutrients, optimal temperature, light, and gravity. Development encompasses growth and differentiation, where cells specialize for specific functions. The chapter details five plant growth regulators (auxins, gibberellins, cytokinins, ethylene, and abscisic acid) that control flowering, ripening, dormancy, and stress responses. Dedifferentiation allows mature cells to regain division capacity, creating new tissues through redifferentiation—enabling plant plasticity in response to environment.
Key points & formulas
- 01Growth is irreversible size increase measured by fresh/dry weight, length, area, volume, or cell number, driven by meristematic cell division.
- 02Three growth phases—meristematic (active cell division), elongation (cell enlargement and vacuolation), and maturation (cell wall thickening and specialization).
- 03Arithmetic growth shows linear increase; geometric growth shows exponential increase followed by plateau (sigmoid curve).
- 04Plant growth regulators—auxins (rooting, flowering, apical dominance), gibberellins (elongation, ripening), cytokinins (cell division, leaf growth), ethylene (ripening, senescence), and abscisic acid (stress tolerance, dormancy)—control all developmental phases.
- 05Differentiation specializes cells for function; dedifferentiation restores division capacity; redifferentiation specializes anew—enabling plant flexibility and tissue regeneration.
- 06Development requires intrinsic factors (PGRs, genetics) and extrinsic factors (light, temperature, water, oxygen, nutrients, gravity).
Frequently asked questions
01What is the difference between growth and differentiation in plants?
Growth is irreversible increase in size through cell division and enlargement in meristems, while differentiation is the process where cells develop specialized structures and functions. Development is the sum of both processes—growth provides new cells, differentiation specializes them for their roles.
02What are plant growth regulators and how do they control development?
Plant growth regulators (PGRs) are small molecules including auxins, gibberellins, cytokinins, ethylene, and abscisic acid. Auxins promote rooting and flowering; gibberellins elongate stems and delay ripening; cytokinins promote cell division and leaf growth; ethylene ripens fruits and promotes senescence; abscisic acid acts as a stress hormone and inhibits growth. These regulators work individually, synergistically, or antagonistically to control all phases of plant growth and development.
03Is the NCERT Class 11 Biology Chapter 13 PDF free to download?
Yes, the NCERT Class 11 Biology Chapter 13 PDF is free to download. The chapter covers plant growth and development, including meristematic growth phases, growth rates, plant growth regulators, differentiation, and development processes.
04What three phases occur during plant growth?
Plant growth occurs in three phases: the meristematic phase (rapidly dividing cells at root and shoot apices with large nuclei and thin primary cell walls), the elongation phase (cells enlarge through vacuolation and new cell wall deposition), and the maturation phase (cells attain maximum size with thickened walls and specialized protoplasm for their final functions).
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This is the complete Biology Chapter 13 as published by NCERT — every diagram, solved example, and exercise included, free. Browse all NCERT Class 11 textbooks.
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