THE ULTIMATE PP-03 CHEAT SHEET
Block 1: Growth Basics
- Growth = IRREVERSIBLE permanent increase in size
- Three phases: Meristematic → Elongation → Maturation
- Sigmoid curve: Lag → Log → Stationary
- Arithmetic: Lt = L0 + rt (one daughter divides, linear)
- Geometric: W1 = W0eʳᵗ (both daughters divide, exponential)
- AGR max at INFLECTION POINT of sigmoid curve
Block 2: Five PGRs — Quick Table
| PGR | Type | Key Action | NEET Point |
|---|
| Auxin (IAA) | Indole | Elongation, apical dominance | Low = promote; High = inhibit |
| Gibberellin (GA3) | Terpenoid | Bolting, alpha-amylase (aleurone) | Bakanae disease = Kurosawa |
| Cytokinin | Adenine | Cell division, Richmond-Lang | Kinetin from herring sperm DNA |
| Ethylene | Gas | Ripening, abscission, triple response | ONLY gaseous hormone |
| ABA | Terpenoid | K+ efflux, stomatal closure, dormancy | STRESS HORMONE |
Block 3: Discoveries
| Hormone | Scientist | Source/Method |
|---|
| Auxin | F.W. Went | Avena coleoptile |
| Gibberellin | Kurosawa | Gibberella fujikuroi |
| Kinetin | Skoog & Miller | Herring sperm DNA |
| Ethylene | Cousins | Gas burners (orange ripening) |
| ABA | Addicott & Carns | Cotton boll abscission |
Block 4: Photoperiodism — MEMORIZE THESE
SDP (need long nights): Rice, Chrysanthemum, Tobacco, Xanthium, Soybean
LDP (need short nights): Wheat, Radish, Spinach, Henbane
DNP (don't care): Tomato, Cucumber, Sunflower
Pfr = active phytochrome
- In LDP: Pfr → PROMOTES flowering
- In SDP: Pfr → INHIBITS flowering
Block 5: Differentiation Types
| Type | Process | Example |
|---|
| Differentiation | Meristematic → Permanent | Meristem → Tracheids |
| Dedifferentiation | Permanent → Meristematic | Parenchyma → Interfascicular cambium |
| Redifferentiation | Meristematic → Permanent (again) | Cambium → Secondary xylem |
Block 6: Critical Antagonisms
- GA vs ABA: GA breaks dormancy; ABA maintains dormancy
- Auxin vs Cytokinin: Auxin = apical dominance; Cytokinin = lateral bud promotion
- Ethylene vs Auxin: Ethylene promotes abscission; Auxin suppresses abscission
Block 7: Agricultural Applications
- 2,4-D → herbicide (kills dicots, not monocots)
- NAA → prevents fruit drop, rooting of cuttings
- GA3 → grape elongation, malting (alpha-amylase), bolting
- Cytokinin → delays leaf yellowing (post-harvest)
- Ethephon → uniform banana ripening, pineapple flowering
- ABA → antitranspirant (stomatal closure)
Block 8: NEET Traps to Avoid
- Ethylene: gaseous hormone (NOT ABA)
- ABA: stress hormone (NOT ethylene)
- BOTH auxin AND gibberellin cause parthenocarpy
- SDPs need LONG NIGHTS (not short days!)
- Pfr INHIBITS SDP, PROMOTES LDP
- Cytokinins = ADENINE derivatives (not terpenoids)
- GA and ABA both = TERPENOIDS
- Vernalization = COLD (not light)
- Vernalization perception = SHOOT APEX (not leaves)
- Photoperiodism perception = LEAVES (not apex)
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