General Science & Technology

🟢 Lite — Quick Review (1h–1d)

Physics — Key Laws & Principles

1. Newton’s Laws of Motion (1687):

   • First (Law of Inertia): Object at rest stays at rest; object in motion stays in motion unless acted upon by external force
   • Second: F = ma (Force = mass × acceleration); momentum change per unit time
   • Third: Every action has equal and opposite reaction

2. Law of Gravitation (1687): Every particle attracts every other particle; F = G(m₁m₂)/r²; G = 6.674 × 10⁻¹¹ Nm²/kg²; g (acceleration due to gravity) = 9.8 m/s² on Earth’s surface

3. Kepler’s Laws (1609-1619): Planets orbit in ellipses; equal areas in equal times; T² ∝ r³

4. Optics:

   • Laws of Reflection: Angle of incidence = Angle of reflection
   • Laws of Refraction: Snell’s Law — n₁ sin θ₁ = n₂ sin θ₂
   • Total Internal Reflection: Used in optical fibres

5. Electricity:

   • Ohm’s Law: V = IR (Voltage = Current × Resistance)
   • Power: P = VI = I²R = V²/R (measured in Watts)
   • Coulomb’s Law: F = k(q₁q₂)/r²

Chemistry — Key Concepts

1. Periodic Table: 118 elements; groups (1-18); periods (1-7); metals, non-metals, metalloids
2. Chemical Reactions: Combination, decomposition, displacement, double displacement, redox
3. Acids & Bases: pH scale (0-14); acid (H⁺ donor), base (OH⁻ donor); indicators; neutralisation
4. Atomic Structure: Protons (+), neutrons (neutral), electrons (-); shells; valence electrons

Biology — Key Concepts

1. Cell: Basic unit of life; prokaryotic (bacteria) vs eukaryotic (plants, animals); plant cell has cell wall, chloroplast; animal cell has centrioles
2. Nutrition: Autotrophic (photosynthesis) vs heterotrophic (consumption); nutrients — carbohydrates, proteins, fats, vitamins, minerals, water
3. Human Body Systems: Digestive, circulatory, respiratory, nervous, excretory, skeletal, muscular, endocrine, immune
4. Common Diseases: Viral (common cold, influenza, dengue, COVID-19); bacterial (tuberculosis, typhoid); deficiency diseases (scurvy — Vitamin C, rickets — Vitamin D)

⚡ Exam Tip: AILET GK has 4-6 questions from Science & Technology. Focus on application-based questions — how laws work in daily life. Don’t just memorise formulas; understand concepts.

---

🟡 Standard — Regular Study (2d–2mo)

Physics — Detailed Concepts

Motion & Laws:

• Velocity: Displacement/time; vector quantity; speed is scalar
• Acceleration: Change in velocity/time; m/s²
• Circular motion: v = ωr; centripetal force = mv²/r; centrifugal force (pseudo)
• Friction: Static (object at rest), kinetic (object moving); reduces efficiency
• Work, Energy, Power:
  • Work = Force × displacement × cos θ (Joules)
  • Kinetic Energy = ½mv²; Potential Energy = mgh (gravitational)
  • Conservation of Energy: Energy neither created nor destroyed; transformed
  • Power = Work/time = Energy/time (Watts)

Gravitation:

• g varies: Higher at poles, lower at equator; decreases with altitude; increases with depth (initially)
• Escape velocity: 11.2 km/s from Earth; v = √(2gR)
• Satellites: Geostationary (24,000 km above equator, same rotational period); polar (low Earth orbit)
• Weight: Force due to gravity; varies with location; mass constant

Light & Optics:

• Reflection: Plane mirror — image laterally inverted, same size, virtual; spherical mirrors — concave (real inverted images possible), convex (always virtual, diminished)
• Refraction: Light bends when changing medium; bending direction depends on density
• Lenses: Convex (converging; used for hypermetropia); Concave (diverging; myopia)
• Dispersion: White light splits into 7 colours (VIBGYOR); rainbow formation
• Human eye: Cornea (refracts); lens (accommodates); retina (image formation); nearest point of distinct vision (25 cm); far point (infinity)
• Defects: Myopia (near-sighted; concave lens); Hypermetropia (far-sighted; convex lens); Presbyopia (age; bifocals); Astigmatism (cylinder lens); Cataract (lens clouding); Glaucoma (optic nerve damage)

Electricity & Magnetism:

• Current: Flow of electrons; 1 ampere = 1 coulomb/second
• Resistance: R = ρL/A; ohm’s law; series (add up) vs parallel (1/R = 1/R₁ + 1/R₂)
• Magnetic effects: Oersted’s experiment; solenoid; electromagnet; electric motor (converts electrical to mechanical); generator (mechanical to electrical)
• Electromagnetic induction: Faraday’s law; Lenz’s law (conservation of energy); transformer (step up/step down voltage)
• Household wiring: Live (brown/red), neutral (blue), earth (green/yellow); fuse (overcurrent protection)

Chemistry — Detailed

Atomic Structure:

• Rutherford’s gold foil experiment: Nucleus at centre; mostly empty space
• Bohr’s model: Electrons in fixed orbits (shells); energy levels; jumps with photon emission/absorption
• Electronic configuration: Aufbau principle; Hund’s rule; Pauli exclusion principle
• Isotopes: Same atomic number, different mass number (e.g., deuterium, tritium)
• Ions: Cations (+ve, lose electrons); Anions (-ve, gain electrons)

Periodic Table:

• Groups: 1-Alkali metals (reactive); 2-Alkaline earth metals; 13-18: B, Si, P, S, Cl, Noble gases
• Periods: 1 (H, He); 2 (Li to Ne); 3 (Na to Ar); 4 (K to Kr — first transition series)
• Trends: Atomic size decreases across period; ionisation energy increases; electronegativity increases; metallic character decreases
• Metalloids: B, Si, Ge, As, Sb, Te, Po — properties of both metals and non-metals

Chemical Bonding:

• Ionic (electrovalent): Transfer of electrons (e.g., NaCl); strong; crystalline
• Covalent: Sharing of electrons; (e.g., H₂O, CO₂); diamond (covalent network); graphite
• Metallic: Sea of electrons; malleable; conductors
• Hydrogen bonding: Weak bond between H and electronegative atom (F, O, N); water’s high boiling point; DNA double helix

Important Chemical Reactions:

• Combustion: Fuel + O₂ → CO₂ + H₂O + heat
• Oxidation-Reduction (Redox): One species loses electrons (oxidation), other gains (reduction); oxidising agent, reducing agent
• Neutralisation: Acid + Base → Salt + Water
• Decomposition: CaCO₃ → CaO + CO₂ (on heating)
• Displacement: Zn + CuSO₄ → ZnSO₄ + Cu

Acids & Bases:

• Arrhenius: Acid produces H⁺ in water; base produces OH⁻
• Bronsted-Lowry: Acid is H⁺ donor; base is H⁺ acceptor
• Lewis: Acid is electron pair acceptor; base is electron pair donor
• pH: 0-6 (acidic); 7 (neutral); 8-14 (basic)
• Common acids: HCl (stomach), H₂SO₄ (battery), HNO₃ (explosives); bases: NaOH (caustic soda), Ca(OH)₂ (lime)
• Indicators: Litmus (blue-red for acid, red-blue for base); phenolphthalein (colourless-pink in base); methyl orange (red-orange-yellow)

Biology — Detailed

Cell — Structure & Function:

• Cell membrane: Phospholipid bilayer; selectively permeable; Fluid Mosaic Model
• Nucleus: Contains DNA (chromatin); nuclear envelope; nucleolus (rRNA synthesis)
• Mitochondria: Powerhouse; produces ATP (cellular respiration); own DNA (endosymbiont theory)
• Chloroplast: Site of photosynthesis; contains chlorophyll; also own DNA
• Endoplasmic reticulum: Rough (ribosomes attached; protein synthesis); Smooth (lipid synthesis)
• Golgi apparatus: Modifies, packages, secretes proteins
• Lysosomes: Contain digestive enzymes; autophagy
• Plant cell: Cell wall (cellulose); chloroplasts; large central vacuole; no centrioles
• Animal cell: Centrioles (cilia/flagella); lysosomes; smaller vacuoles

Nutrition:

• Carbohydrates: CH₂O; main energy source; monosaccharides (glucose, fructose), disaccharides (sucrose, lactose), polysaccharides (starch, glycogen, cellulose)
• Proteins: Amino acids; essential (8-9); complete (animal); incomplete (plant); 4 cal/g
• Fats: Saturated (solid; animal); unsaturated (liquid; plant); 9 cal/g
• Vitamins: Fat-soluble (A, D, E, K — stored); water-soluble (B-complex, C — excreted)
• Minerals: Calcium (bones), Iron (haemoglobin), Iodine (thyroid), Phosphorus (ATP)

Human Body Systems:

1. Digestive: Mouth → Oesophagus → Stomach → Small intestine (duodenum, jejunum, ileum) → Large intestine → Rectum; accessory organs (liver, pancreas, gallbladder)
2. Circulatory: Heart (4 chambers — 2 atria, 2 ventricles); double circulation; systemic and pulmonary; blood vessels (arteries, veins, capillaries); blood components (RBC, WBC, platelets, plasma)
3. Respiratory: Nose → Pharynx → Larynx → Trachea → Bronchi → Bronchioles → Alveoli; gas exchange (O₂ diffuses in, CO₂ diffuses out); haemoglobin transports O₂
4. Nervous: CNS (brain, spinal cord); PNS (somatic, autonomic); neurons (sensory, motor, relay); synapse; reflex arc; brain parts (forebrain, midbrain, hindbrain)
5. Excretory: Kidneys (filtration, reabsorption, secretion); nephron (functional unit); bladder; urethra; urine formation (glomerular filtration, tubular reabsorption, tubular secretion)

Diseases:

• Deficiency diseases: Anaemia (iron), Goitre (iodine), Rickets (Vitamin D), Scurvy (Vitamin C), Beriberi (B1), Night blindness (Vitamin A)
• Communicable: COVID-19 (SARS-CoV-2; droplets; vaccines), Tuberculosis (Mycobacterium; cough), Malaria (Plasmodium; mosquito), Dengue (Aedes aegypti; fever, platelets), Cholera (Vibrio cholerae; water), Typhoid (Salmonella; fever)
• Lifestyle diseases: Diabetes (Type 1 — insulin deficiency; Type 2 — insulin resistance), Hypertension (high blood pressure), Obesity (BMI >30)

---

🔴 Extended — Deep Study (3mo+)

Physics — Advanced Concepts

Waves:

• Types: Mechanical (sound, water — need medium); Electromagnetic (light, radio — no medium; speed = 3×10⁸ m/s)
• Properties: Wavelength (λ), frequency (f), speed (v = fλ), amplitude (intensity)
• Sound: Longitudinal wave; 340 m/s in air; audible range 20-20,000 Hz; infrasound (<20Hz); ultrasound (>20kHz); echo; reverberation
• Doppler effect: Change in frequency due to relative motion; used in radar, astronomy

Thermodynamics:

• Laws: 0th (thermal equilibrium); 1st (energy conserved; ΔU = Q - W); 2nd (entropy increases; heat flows hot to cold); 3rd (absolute zero unattainable)
• Heat transfer: Conduction (solids), convection (fluids), radiation (electromagnetic)
• Specific heat capacity: Energy to raise 1 kg by 1°C; water = 4200 J/kg°C (highest)

Modern Physics:

• Photoelectric effect: Einstein (1905); photon ejects electrons; supports particle nature of light
• Wave-particle duality: de Broglie; λ = h/p
• Radioactivity: Alpha (He nucleus; stopped by paper), Beta (electron; stopped by aluminium), Gamma (EM wave; stopped by lead)
• Nuclear fission: Uranium-235; chain reaction; E = mc²; nuclear reactors
• Nuclear fusion: Hydrogen nuclei fuse; powers sun; hydrogen bomb; not yet controlled for energy production

Chemistry — Advanced

Organic Chemistry Basics:

• Hydrocarbons: Alkanes (single bonds), Alkenes (C=C), Alkynes (C≡C)
• Functional groups: Alcohol (-OH), Aldehyde (-CHO), Ketone (-CO-), Carboxylic acid (-COOH), Ester
• Polymers: Monomers join; addition (polythene) vs condensation (nylon, polyester)
• Biomolecules: Carbohydrates (glucose, cellulose), Proteins (amino acids), Fats (glycerol + fatty acids), Nucleic acids (DNA, RNA — nucleotides)

Environmental Chemistry:

• Ozone layer: O₃; depletion by CFCs (chlorofluorocarbons); Montreal Protocol (1987); UV protection
• Greenhouse gases: CO₂, CH₄, N₂O, CFCs; global warming; climate change
• Water pollution: BOD (Biological Oxygen Demand); DO (Dissolved Oxygen); eutrophication; sewage treatment
• Acid rain: SO₂, NOₓ → sulphuric, nitric acid; damages buildings, forests; limestone statues

Biology — Advanced

Genetics:

• DNA: Double helix (Watson & Crick, 1953); antiparallel strands; complementary base pairing (A-T, G-C)
• RNA: Single stranded; mRNA (messenger), tRNA (transfer), rRNA (ribosomal)
• Replication: Semi-conservative (Meselson-Stahl experiment); enzyme DNA polymerase
• Transcription & Translation: DNA → mRNA → Protein (central dogma)
• Mendel’s Laws: Dominance, Segregation, Independent Assortment
• Genetic disorders: Sickle cell anaemia (HbS gene), Haemophilia (X-linked), Down syndrome (trisomy 21), PKU (phenylketonuria)

Evolution:

• Darwin’s theory: Natural selection; survival of fittest; variation; adaptation
• Evidence: Fossils, homologous structures, vestigial organs, biogeography, molecular
• Lamarckism: Inheritance of acquired characteristics (discredited)
• Human evolution: Homo habilis → Homo erectus → Homo sapiens (modern); primates common ancestor

Ecology:

• Food chain: Producers → Primary consumers → Secondary consumers → Tertiary consumers → Decomposers
• Food web: Interconnected food chains
• Ecological pyramids: Number, biomass, energy (always upright)
• Biogeochemical cycles: Carbon (photosynthesis-respiration), Nitrogen (nitrogen fixation), Water
• Biodiversity hotspots: 36 globally; Western Ghats, Himalayas, Sundarbans in India
• Conservation: In situ (national parks, biosphere reserves) vs ex situ (zoos, seed banks); IUCN Red List; CITES

Biotechnology:

• Recombinant DNA: Gene cloning; restriction enzymes; vectors; transformation
• PCR (Polymerase Chain Reaction): Amplifies DNA; forensic, medical
• CRISPR-Cas9: Gene editing; precision; potential to cure genetic diseases
• Applications: Insulin production (E. coli), Bt cotton, golden rice, gene therapy

Information Technology

• Computer basics: Hardware (CPU — ALU, CU, registers); Software (OS, applications)
• Internet: TCP/IP protocol; WWW; HTTP/HTTPS; DNS; Cloud computing
• AI (Artificial Intelligence): Machine learning; deep learning; neural networks; ChatGPT, AlphaFold
• Blockchain: Decentralised ledger; cryptocurrency (Bitcoin); transparency; smart contracts
• Cybersecurity: Encryption; phishing; malware; ransomware; GDPR; IT Act 2000 (India)

Space Technology

• ISRO (Indian Space Research Organisation): Founded 1969; headquarters Bengaluru; chairman
• Satellites: IRS series (remote sensing); INSAT series (communication, weather); GSAT (communication)
• Chandrayaan missions: Chandrayaan-1 (2008 — water ice on moon); Chandrayaan-2 (2019 — orbiter, lander, rover); Chandrayaan-3 (2023 — soft landing on moon south pole)
• Mars Orbiter Mission (Mangalyaan, 2013): First attempt by any country to succeed in first attempt; cost effective
• Gaganyaan: Indian human spaceflight programme; planned 2025
• Aditya-L1: Solar mission; L1 point (1.5 million km from Earth)

Common Mistakes to Avoid

1. Confusing mass and weight — mass constant, weight varies with gravity
2. Mixing up speed of sound vs speed of light
3. Thinking parallel circuit has higher voltage — it’s lower effective resistance
4. Confusing acids and bases by pH alone — strong vs weak matters
5. Forgetting that glucose is broken down in cytoplasm first (glycolysis), then mitochondria
6. Not knowing difference between DNA and RNA bases
7. Mixing up virus and bacteria — viruses not cells; need host to reproduce

Practice Tips

• Practice numerical problems from physics (motion, electricity, light)
• Draw diagrams for biology (cell structure, body systems)
• Memorise chemical formulas and equations
• Solve AILET GK on Science focusing on application-based questions
• Prepare notes on recent technology achievements (ISRO, AI developments)