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Plant Growth and Development

NCERT Class 11 Biology Chapter 13

Plant Growth and Development for Class 11 Biology and NEET: seed germination, growth phases and rates, differentiation, development and growth regulators.

5 topics Updated 8 Nov 2026

For: Class 11 and NEET, unless a topic says otherwise

In the syllabus: NEET Class 11 syllabus

With your textbook

NCERT Biology (Class 11), Chapter 13 “Plant Growth and Development”, reprint 2026-27.

Open the official NCERT chapter (PDF, 1.9 MB, ncert.nic.in)

Checked on 19 Oct 2026.

Learn in this order

  1. Seed germination: conditions and types

    Conditions a seed needs, epigeal and hypogeal germination with examples and a diagram, dormancy, and how the seedling emerges.

    NEET only 12 min read 5 solved examples 7 practice questions

  2. Growth in plants: phases, rates and curves

    Phases of growth, arithmetic and geometric growth, a sigmoid growth curve diagram, growth rates and solved examples.

    NCERT Section 13.1 15 min read 6 solved examples 8 practice questions

  3. Differentiation, dedifferentiation and redifferentiation

    Definitions, tracheary elements, cork and interfascicular cambium.

    NCERT Section 13.2 9 min read 5 solved examples 7 practice questions

  4. Development in plants: sequence and plasticity

    Plant development for Class 11 Biology and NEET: the developmental sequence of a plant cell, plasticity and heterophylly, and the factors that control it.

    NCERT Section 13.3 6 min read 4 solved examples 6 practice questions

  5. Plant growth regulators: auxin to ABA

    Auxin, gibberellin, cytokinin, ethylene and ABA, their functions and uses, apical dominance and bolting.

    NCERT Section 13.4 16 min read 5 solved examples 9 practice questions

Key formulas in this chapter

Seed germination

  • conditions: adequate moisture, oxygen, suitable temperature
  • epigeal: hypocotyl elongates; cotyledons above the soil (bean)
  • hypogeal: cotyledons in the soil (pea, maize); epicotyl elongates in pea
  • coleoptile: sheath of the plumule; coleorhiza: sheath of the radicle
  • abscisic acid inhibits germination; ethylene breaks seed dormancy

Growth

  • arithmetic growth: Lt = L0 + rt
  • geometric growth: W1 = W0e^{rt}, r = relative growth rate (efficiency index)
  • growth rate = increased growth per unit time
  • relative growth rate = growth per unit time ÷ initial size
  • S-curve: lag → log (exponential) → stationary
  • phases of growth: meristematic → elongation → maturation

Differentiation, dedifferentiation and redifferentiation

  • differentiation: meristem-derived cell → specialised mature cell
  • dedifferentiation: mature living cell → divides again (interfascicular cambium, cork cambium)
  • redifferentiation: products of the new meristem → mature cells again
  • tracheary element: loses protoplasm; lignocellulosic secondary wall

Development

  • development = growth + differentiation
  • meristematic cell → plasmatic growth → expansion → differentiation → maturation → mature cell → senescence → death
  • plasticity: different structures for environment or phase of life
  • intrinsic: genetic, plant growth regulators; extrinsic: light, temperature, water, oxygen, nutrition

Plant growth regulators

  • promoters: auxins, gibberellins, cytokinins; inhibitor: abscisic acid; ethylene: largely an inhibitor
  • auxin: rooting, apical dominance, parthenocarpy, 2,4-D herbicide
  • gibberellin: stem and stalk lengthening, bolting, malting
  • cytokinin: cell division, overcomes apical dominance, delays leaf senescence
  • ethylene: fruit ripening, abscission, breaks dormancy; source: ethephon
  • abscisic acid: stomatal closure, dormancy; the stress hormone

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