Plant Growth and Development NEET 2026 | Notes, MCQs & PYQs
| Topic | Key Points |
|---|---|
| Chapter | Plant Growth and Development |
| Introduction | Growth and development in plants involve cell division, enlargement, and differentiation, regulated by plant hormones. |
| Plant Hormones | Auxin, Gibberellins (GA), Abscisic Acid (ABA) |
| What is Plant Growth? | A permanent and irreversible increase in size, volume, or number of cells. |
| Characteristics of Growth |
|
| Meristematic Phase | Region of active cell division located at root and shoot tips. |
| Elongation Phase | Cells increase in size due to vacuole enlargement and cell expansion. |
| Maturation Phase | Cells attain maximum size and become specialized for specific functions. |
Every seed you sow holds the potential to become a magnificent plant. But what makes it grow?
Growth and development in plants are not random — they follow a well-coordinated process involving cell division, enlargement, and differentiation, all controlled by plant hormones.
For NEET aspirants, this chapter is a frequently tested section in Plant Physiology. Let’s break it down in a simple, clear, and exam-oriented way.
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Explore NEET Biology →๐ณ Section 1: What is Plant Growth?
Growth is a permanent, irreversible increase in size, volume, or number of cells.
In plants, growth is indeterminate, meaning it continues throughout life due to the presence of meristems.
๐ Characteristics of Growth
1. Irreversible: Once a cell enlarges, it cannot return to its previous size.
2. Permanent: The increase remains stable over time.
3. Metabolically active: Requires energy from respiration.
4. Quantitative: Can be measured (length, volume, weight, etc.).
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๐ฟ Section 2: Phases of Growth
Growth in plants occurs in three distinct phases.
Imagine a root tip — it beautifully demonstrates all three:
1️⃣ Meristematic Phase (Region of cell division):
Located at root and shoot tips.
Cells are small, rich in cytoplasm, and actively dividing.
Example: Root apical meristem, shoot apical meristem.
2️⃣ Elongation Phase:
Cells increase in size due to vacuole enlargement.
Responsible for the lengthening of the plant organ.
3️⃣ Maturation Phase:
Cells attain permanent shape and function.
Tissues differentiate into xylem, phloem, etc.
๐น Graphical Representation:
Growth curve is sigmoid (S-shaped) — includes lag, log (exponential), and stationary phases.
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๐บ Section 3: Growth Rate
Growth rate is the increase in growth per unit time.
Formula:
Relative Growth Rate (RGR) =
Where W = Weight, t = Time
Types of Growth:
Arithmetic Growth: One daughter cell divides while the other differentiates.
Example: Root elongation.
Formula:
Geometric Growth: Both cells divide continuously (as in meristematic tissues).
Formula:
NEET Tip:
Growth rate is maximum during the log phase.
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๐พ Section 4: Conditions for Growth
Plant growth depends on intrinsic and extrinsic factors:
Intrinsic: Hormones, genes, enzyme systems.
Extrinsic: Temperature, water, oxygen, nutrients, and light.
Water: Essential for cell enlargement.
Temperature: Optimum 25–30°C.
Light: Regulates photomorphogenesis.
Minerals: Nitrogen and potassium aid growth.
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๐ผ Section 5: Plant Growth Regulators (Plant Hormones)
Plants coordinate growth using chemical messengers called hormones or phytohormones.
There are five major hormones with distinct roles.
Hormone Site of Synthesis Function Example NEET Question
Auxins Shoot tip Cell elongation, apical dominance IAA promotes rooting
Gibberellins (GA) Young leaves, seeds Stem elongation, seed germination GA breaks seed dormancy
Cytokinins Root tips Cell division, delay in senescence Found in coconut milk
Abscisic Acid (ABA) Mature leaves Stress hormone, stomatal closure Causes seed dormancy
Ethylene Ripening fruits Fruit ripening, abscission Induces triple response
Easy Trick to Remember:
๐ “A Great Cook Always Eats”
(Auxin – GA – Cytokinin – ABA – Ethylene
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๐ป Section 6: Development and Differentiation
Development = Sum total of growth + differentiation + maturation.
Differentiation: Cells become specialized (e.g., tracheids, xylem vessels).
Dedifferentiation: Mature cells regain ability to divide (e.g., interfascicular cambium).
Redifferentiation: Dedifferentiated cells again become specialized.
Example:
Parenchyma → Cambium → Secondary xylem/phloem
NEET Concept Link:
Tissue culture depends on the totipotency of cells — ability to form a whole plant from one cell.
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๐ฟ Section 7: Photoperiodism
Plants respond to day and night length — this is called photoperiodism.
It controls flowering and growth patterns.
Type of Plant Flowering Condition Example
Short Day Plants < 12 hours light Rice, Chrysanthemum
Long Day Plants > 12 hours light Wheat, Barley
Day Neutral Plants Independent of day length Tomato, Cucumber
Receptor: Phytochrome — a light-sensitive pigment.
Forms:
Pr absorbs red light (660 nm)
Pfr absorbs far-red light (730 nm)
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๐ธ Section 8: Vernalization
Vernalization = Flowering induced by prolonged exposure to low temperature.
Example:
Wheat, cabbage, and beet require cold treatment to flower.
NEET Question Example:
“Which plant hormone replaces the need for vernalization?”
๐ Gibberellin (GA)
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๐ฑ Section 9: Seed Dormancy and Germination
Seeds remain dormant due to presence of ABA.
Breaking dormancy involves:
Leaching of inhibitors
Softening of seed coat
Application of Gibberellin (GA₃)
Germination Types:
1. Epigeal: Cotyledons above soil (Bean, Castor).
2. Hypogeal: Cotyledons below soil (Maize, Pea).
Condition Required for Germination: Water, oxygen, optimum temperature, and sometimes light.
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๐ง Section 10: NEET PYQs on Plant Growth and Hormones
1️⃣ NEET 2023:
Which hormone is responsible for fruit ripening?
✅ Ethylene
2️⃣ NEET 2021:
Apical dominance is caused by:
✅ Auxin
3️⃣ NEET 2020:
Which hormone promotes seed dormancy?
✅ Abscisic Acid
4️⃣ NEET 2019:
Which hormone delays senescence?
✅ Cytokinin
5️⃣ NEET 2018:
Which process converts meristematic cells to permanent cells?
✅ Differentiation
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๐ฟ Section 11: Summary Table for Quick Revision
Concept Keyword Example
Growth Irreversible increase Root tip elongation
Phases Meristematic → Elongation → Maturation Root apex
Hormones Auxin, GA, Cytokinin, ABA, Ethylene Different functions
Development Growth + Differentiation Totipotency
Photoperiodism Day length effect Rice, Wheat
Vernalization Cold treatment Cabbage, Beet
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๐บ Conclusion
Plant Growth and Development เคนเคฎें เคฏเคน เคธเคฎเคเคจे เคฎें เคฎเคฆเคฆ เคเคฐเคคा เคนै เคि เคชौเคงे เคैเคธे เคฌเคข़เคคे เคนैं, เคเคจเคी cells เค เคฒเค-เค เคฒเค functions เคे เคฒिเค เคैเคธे differentiate เคนोเคคी เคนैं, เคเคฐ plant hormones growth เคคเคฅा development เคो เคैเคธे regulate เคเคฐเคคे เคนैं।
NEET เคी เคคैเคฏाเคฐी เคฎें เคเคธ chapter เคो เคธिเคฐ्เคซ hormones เคी list เคฏाเคฆ เคเคฐเคे เคเคค्เคฎ เคฎเคค เคीเคिเค। Auxin, Gibberellin, Cytokinin, Ethylene เคเคฐ ABA เคे functions เคเค เคเคเคน similar เคฒเค เคธเคเคคे เคนैं, เคเคฐ เคฏเคนीं MCQs เคฎें confusion เคถुเคฐू เคนोเคคा เคนै। เคเคธเคฒिเค เคนเคฐ plant growth regulator เคो เคเคธเคे เคช्เคฐเคฎुเค functions, practical examples เคเคฐ เคฆूเคธเคฐे hormones เคे เคธाเคฅ interaction เคे เคเคงाเคฐ เคชเคฐ เคธเคฎเคเคจे เคी เคोเคถिเคถ เคเคฐें।
Revision เคे เคฆौเคฐाเคจ growth phases, sigmoid growth curve, differentiation, dedifferentiation, redifferentiation เคเคฐ plant growth regulators เคैเคธे NCERT concepts เคชเคฐ เคाเคธ เคง्เคฏाเคจ เคฆें। เคเคจเคे short comparison charts เคฌเคจाเคเคฐ เคเคฐ เคจिเคฏเคฎिเคค MCQ practice เคे เคธाเคฅ revise เคเคฐเคจे เคธे chapter เคो เคฏाเคฆ เคฐเคเคจा เคเคฐ similar options เคे เคฌीเค เคธเคนी answer เคชเคนเคाเคจเคจा เคाเคซी เคเคธाเคจ เคนो เคธเคเคคा เคนै।
