General Science Revision Notes – Social Forestry Worker Exam
Physics · Chemistry · Biology · Everyday Science · Environmental Science
This guide provides concise, exam-focused revision notes across key science topics. Use the structured headings, tables, and mnemonics for efficient study.
1. Physics
| Concept | Key Points / Formulas | Everyday Example |
|---|---|---|
| Motion | • Speed = distance / time • Velocity = displacement / time (vector) • Acceleration = (v−u)/t • Equations of motion (uniform a): 1) v = u + at 2) s = ut + ½at² 3) v² = u² + 2as |
• Car accelerating on a highway • Free‑fall of a leaf (g≈9.8 m/s²) |
| Force & Laws of Motion | • Newton’s 1st law – inertia • 2nd law – F = ma • 3rd law – action = reaction • Weight = mg (g≈9.8 m/s²) |
• Pushing a loaded cart • Rocket launch (exhaust gases down, rocket up) |
| Work, Energy & Power | • Work = F·d·cosθ (J) • Kinetic Energy (KE) = ½mv² • Potential Energy (PE) = mgh • Conservation: KE₁+PE₁ = KE₂+PE₂ • Power = Work / time = Fv (W) |
• Lifting a sack of fertilizer • Solar panel converting sunlight to electrical power |
| Simple Machines | • Mechanical Advantage (MA) = Load / Effort • Velocity Ratio (VR) = Distanceeffort / Distanceload • Efficiency = (MA/VR)×100% • Types: Lever, Pulley, Inclined plane, Wheel‑axle, Screw, Wedge |
• Using a crowbar to lift a log (lever) • Pulley system to raise seedlings |
| Sound | • Speed of sound in air ≈ 340 m/s • Frequency (f) = 1/T (Hz) • Pitch ∝ frequency; Loudness ∝ amplitude • Echo: minimum distance = v·t/2 |
• Bird calls in forest surveys • Measuring tree height with sonar |
| Light & Optics | • Reflection: anglei = angler • Refraction: n₁sinθ₁ = n₂sinθ₂ (Snell’s law) • Lens formula: 1/f = 1/v + 1/u • Power of lens (P) = 1/f (metres) → Dioptre (D) |
• Hand lens to examine leaf stomata • Sunglasses reduce glare |
| Electricity | • Ohm’s Law: V = IR • Resistance (R) = ρL/A • Power: P = VI = I²R = V²/R • Series: Rₛ = R₁+R₂+… ; Parallel: 1/Rₚ = 1/R₁+1/R₂+… • Domestic AC: 230 V, 50 Hz (India) |
• Solar‑powered water pump • Battery‑operated sprayers |
| Magnetism | • Like poles repel, unlike attract • Magnetic field lines: N → S • Electromagnet: B ∝ NI/L • Earth’s magnetic field ≈ 0.3‑0.6 G |
• Compass for orientation • Magnetic separators for soil |
| Heat & Thermodynamics | • Specific heat (c): Q = mcΔT • Latent heat: L (fusion/vaporisation) • First law: ΔU = Q – W • Second law: Heat flows hot→cold • Thermal conductivity (k) |
• Insulating mulch for soil • Compost heat generation |
Physics Mnemonics
- Motion Equations: “VUAT, USE, VUS” → v = u + at; s = ut + ½at²; v² = u² + 2as.
- Newton’s Laws: “1‑Inertia, 2‑Force, 3‑Action‑Reaction”.
- Ohm’s Law Triangle: Cover V → I = V/R; Cover I → V = IR; Cover R → R = V/I.
2. Chemistry
| Topic | Essential Points | Relevance to Forestry |
|---|---|---|
| Matter & States | • Solid, liquid, gas, plasma • Change of state: melting, boiling, sublimation • Latent heat of fusion/vapourisation |
• Water freezing/thawing in soils • Resin exudation from trees |
| Atomic Structure | • Atom = nucleus (p⁺, n⁰) + electrons • Atomic number (Z) = protons • Mass number (A) = p⁺ + n⁰ • Isotopes: same Z, different A |
• Carbon‑14 dating of old wood |
| Periodic Table | • Groups (vertical) – similar valence electrons • Periods (horizontal) – same energy level • Trends: atomic radius, ionization energy, electronegativity |
• Identifying essential nutrients (N, P, K, Ca, Mg, S) and trace elements |
| Chemical Bonding | • Ionic: transfer of e⁻ • Covalent: sharing of e⁻ • Metallic: sea of electrons • Hydrogen bond: H with O,N,F |
• Water’s high specific heat moderates microclimate • Nutrient uptake as ions (NO₃⁻, PO₄³⁻, K⁺) |
| Acids, Bases & Salts | • Acid → H⁺ donor; Base → H⁺ acceptor • pH = –log[H⁺]; <7 acidic, >7 basic • Salt: acid + base → salt + water • Buffer resists pH change |
• Soil pH affects nutrient availability (optimal 5.5‑6.5) • Lime (CaCO₃) raises pH; sulphur lowers it |
| Oxidation‑Reduction (Redox) | • Oxidation = loss of e⁻ • Reduction = gain of e⁻ • Oxidising agent gains e⁻; reducing agent loses e⁻ • OIL RIG (Oxidation Is Loss, Reduction Is Gain) |
• Rusting of iron tools • Microbial respiration of organic matter |
| Carbon Chemistry (Organic Basics) | • Hydrocarbons: alkanes, alkenes, alkynes • Functional groups: –OH, –CHO, –COOH, –NH₂ • Isomerism • Polymerisation: monomers → polymers |
• Cellulose = main wood component • Lignin provides rigidity • Resins, terpenes as defense compounds |
| Fertilizers & Nutrients | • Macro‑nutrients: N, P, K • Secondary: Ca, Mg, S • Micronutrients: Fe, Mn, Zn, Cu, B, Mo |
• NPK ratios on fertilizer bags (e.g., 10‑26‑26) • Slow‑release fertilizers reduce leaching |
| Environmental Chemistry | • Greenhouse gases: CO₂, CH₄, N₂O • Acid rain: SO₂, NOₓ + H₂O → acid • Ozone depletion: CFCs • Photochemical smog |
• Forest carbon sequestration • Acid rain damages leaves and soil |
| Important Formulas | • Mole: n = mass / Molar mass • Molarity: M = moles solute / L solution • Dilution: M₁V₁ = M₂V₂ • Ideal Gas: PV = nRT |
• Calculating fertilizer dosage per hectare • Preparing nutrient solutions |
Chemistry Mnemonics
- Periodic Table (First 10): “Happy Henry Likes Beer But Could Not Obtain Food” (H, He, Li, Be, B, C, N, O, F, Ne).
- Redox: “LEO says GER” (Lose Electrons Oxidation, Gain Electrons Reduction).
- Acid‑Base: “Ate” → Acid gives H⁺; “Base” → OH⁻ (or accepts H⁺).
3. Biology
| Subtopic | Key Points | Application to Social Forestry |
|---|---|---|
| Cell Structure | • Plasma membrane, cytoplasm, nucleus • Mitochondria (ATP), chloroplasts (photosynthesis) • Cell wall (plant) = cellulose, hemicellulose |
• Photosynthesis determines growth rates • Respiration for nutrient uptake energy |
| Plant Tissues | • Meristematic (apical, lateral) → growth • Permanent: simple & complex (xylem, phloem) • Xylem: water & minerals upward • Phloem: sugars downward |
• Xylem blockage → wilting • Pruning stimulates bushier growth |
| Photosynthesis | • 6CO₂ + 6H₂O → C₆H₁₂O₆ + 6O₂ • Light reactions (ATP, NADPH, O₂) • Calvin cycle (CO₂ fixation) • Factors: light, CO₂, temperature, water |
• Shade‑tolerant species have lower light needs • Elevated CO₂ can boost growth |
| Respiration | • C₆H₁₂O₆ + 6O₂ → 6CO₂ + 6H₂O + ATP • Glycolysis → Krebs cycle → ETC |
• Water‑logged soils cause root hypoxia |
| Transpiration & Water Relations | • Water uptake via roots → xylem → stomata • Cohesion‑tension theory • Stomatal regulation by light, CO₂, ABA |
• Mulching reduces water loss • Drought‑resistant species have adaptations |
| Nutrient Uptake | • Ions absorbed via root hairs (active transport) • Mycorrhizal fungi boost P & Zn uptake • Nitrogen fixation: Rhizobium, Frankia |
• Mycorrhizal inoculation improves survival • Nitrogen‑fixing species enrich soil |
| Plant Hormones | • Auxin (IAA) → elongation, apical dominance • Gibberellins → stem growth, germination • Cytokinins → cell division • Ethylene → ripening, abscission • ABA → stomatal closure, dormancy |
• Synthetic auxins as herbicides (2,4‑D) • ABA sprays reduce transplant shock |
| Plant Classification (Basics) | • Bryophytes, Pteridophytes, Gymnosperms, Angiosperms • Monocots (parallel veins) & Dicots (net veins) |
• Most timber species are dicots or gymnosperms |
| Forest Ecology Concepts | • Food Chain/Web, Ecological Pyramids • Succession: primary & secondary • Carrying Capacity (K) |
• Understanding pest outbreaks via food webs • Managing successional stages |
| Biodiversity & Conservation | • Genetic, species, ecosystem diversity • Hotspots, IUCN Red List • Protected Areas: NPs, WLS, Biosphere Reserves |
• Social forestry enhances local biodiversity • Planting native species supports genetics |
| Common Forest Pests & Diseases | • Insects: defoliators, borers, sap‑feeders • Fungi: root rot, canker, rust • Nematodes • Control: cultural, biological, chemical |
• Integrated Pest Management (IPM) • Regular monitoring for early detection |
| Human Physiology Basics (for health & safety) | • Respiratory, circulatory, nervous, excretory systems • First‑aid basics: bleeding, fractures, burns, CPR |
• Recognizing heat‑stress, dehydration, snake‑bite • Proper use of PPE (helmets, gloves, boots) |
Biology Mnemonics
- Plant Hormones: “Aunt Grace Comes Every Afternoon” → Auxin, Gibberellin, Cytokinin, Ethylene, Abscisic Acid.
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