Class 12 NCERT Core Concepts

Cheatsheet Content

Physics: Electrostatics Electric Charges & Fields Quantization of Charge: $q = ne$, where $n = 0, \pm 1, \pm 2, ...$ Conservation of Charge: Total charge in an isolated system remains constant. Coulomb's Law: $F = k \frac{|q_1 q_2|}{r^2}$ (in vacuum), where $k = \frac{1}{4\pi\epsilon_0} = 9 \times 10^9 \text{ Nm}^2/\text{C}^2$. Electric Field: $\vec{E} = \frac{\vec{F}}{q_0}$. For a point charge $Q$, $E = \frac{1}{4\pi\epsilon_0} \frac{Q}{r^2}$. Electric Dipole Moment: $\vec{p} = q(2\vec{a})$, where $2a$ is distance between charges. Torque on Dipole: $\vec{\tau} = \vec{p} \times \vec{E}$. Work Done on Dipole: $W = pE(\cos\theta_1 - \cos\theta_2)$. Potential Energy of Dipole: $U = -\vec{p} \cdot \vec{E}$. Electrostatic Potential & Capacitance Electric Potential: $V = \frac{W}{q_0}$. For a point charge $Q$, $V = \frac{1}{4\pi\epsilon_0} \frac{Q}{r}$. Potential Difference: $V_B - V_A = -\int_A^B \vec{E} \cdot d\vec{l}$. Relation between E & V: $\vec{E} = -\nabla V$. For 1D, $E = -\frac{dV}{dr}$. Equipotential Surfaces: Surfaces with constant potential. E-field lines are perpendicular to them. Capacitance: $C = \frac{Q}{V}$. Unit: Farad (F). Parallel Plate Capacitor: $C = \frac{\epsilon_0 A}{d}$. With dielectric $K$, $C = \frac{K\epsilon_0 A}{d}$. Capacitors in Series: $\frac{1}{C_{eq}} = \frac{1}{C_1} + \frac{1}{C_2} + ...$ Capacitors in Parallel: $C_{eq} = C_1 + C_2 + ...$ Energy Stored in Capacitor: $U = \frac{1}{2}CV^2 = \frac{1}{2}\frac{Q^2}{C} = \frac{1}{2}QV$. Energy Density: $u = \frac{1}{2}\epsilon_0 E^2$. Physics: Current Electricity Electric Current: $I = \frac{dQ}{dt}$. Unit: Ampere (A). Drift Velocity: $v_d = -\frac{eE\tau}{m}$. Relation between I & $v_d$: $I = nAe v_d$. Ohm's Law: $V = IR$. Resistance: $R = \rho \frac{L}{A}$. Unit: Ohm ($\Omega$). Resistivity: $\rho = \frac{m}{ne^2\tau}$. Temperature Dependence of Resistance: $R_T = R_0[1 + \alpha(T - T_0)]$. Resistors in Series: $R_{eq} = R_1 + R_2 + ...$ Resistors in Parallel: $\frac{1}{R_{eq}} = \frac{1}{R_1} + \frac{1}{R_2} + ...$ Kirchhoff's Laws: Junction Rule: $\sum I = 0$ (at any junction). Loop Rule: $\sum \Delta V = 0$ (around any closed loop). Wheatstone Bridge: Balanced condition $\frac{P}{Q} = \frac{R}{S}$. Electric Power: $P = VI = I^2R = \frac{V^2}{R}$. Joule's Law of Heating: $H = I^2Rt$. Physics: Magnetic Effects of Current & Magnetism Magnetic Effects of Current Biot-Savart Law: $d\vec{B} = \frac{\mu_0}{4\pi} \frac{I d\vec{l} \times \hat{r}}{r^2}$. Magnetic Field due to Straight Wire: $B = \frac{\mu_0 I}{2\pi r}$. Magnetic Field at Center of Circular Loop: $B = \frac{\mu_0 I}{2R}$. Magnetic Field on Axis of Circular Loop: $B = \frac{\mu_0 I R^2}{2(R^2 + x^2)^{3/2}}$. Ampere's Circuital Law: $\oint \vec{B} \cdot d\vec{l} = \mu_0 I_{enc}$. Magnetic Field of Solenoid: $B = \mu_0 n I$ (inside), where $n$ is turns per unit length. Magnetic Field of Toroid: $B = \frac{\mu_0 NI}{2\pi r}$. Lorentz Force: $\vec{F} = q(\vec{E} + \vec{v} \times \vec{B})$. Force on Current Carrying Conductor: $\vec{F} = I(\vec{l} \times \vec{B})$. Force between Parallel Currents: $F = \frac{\mu_0 I_1 I_2 l}{2\pi d}$. Torque on Current Loop: $\vec{\tau} = \vec{M} \times \vec{B}$, where $\vec{M} = NI\vec{A}$ (magnetic dipole moment). Magnetism & Matter Bar Magnet: Behaves like a solenoid. Magnetic Field Lines: Form closed loops, outside N to S, inside S to N. Earth's Magnetism: Declination, Dip, Horizontal Component. Magnetic Permeability: $\mu = \mu_r \mu_0$. Magnetic Susceptibility: $\chi_m = \mu_r - 1$. Diamagnetic Materials: Weakly repelled by magnets ($\chi_m Paramagnetic Materials: Weakly attracted by magnets ($\chi_m > 0$). Ferromagnetic Materials: Strongly attracted, show hysteresis ($\chi_m \gg 0$). Physics: EMI & AC Electromagnetic Induction Magnetic Flux: $\Phi_B = \int \vec{B} \cdot d\vec{A} = BA\cos\theta$. Unit: Weber (Wb). Faraday's Law of EMI: $\mathcal{E} = -\frac{d\Phi_B}{dt}$. Lenz's Law: Induced current opposes the change in magnetic flux that produced it. Motional EMF: $\mathcal{E} = Blv$. Self Inductance: $\Phi_B = LI$, $\mathcal{E} = -L\frac{dI}{dt}$. Unit: Henry (H). Mutual Inductance: $\Phi_{21} = MI_1$, $\mathcal{E}_2 = -M\frac{dI_1}{dt}$. Energy Stored in Inductor: $U = \frac{1}{2}LI^2$. Alternating Current AC Voltage/Current: $V = V_0 \sin(\omega t)$, $I = I_0 \sin(\omega t + \phi)$. RMS Values: $V_{rms} = \frac{V_0}{\sqrt{2}}$, $I_{rms} = \frac{I_0}{\sqrt{2}}$. Reactance: Inductive: $X_L = \omega L$. Capacitive: $X_C = \frac{1}{\omega C}$. Impedance (LCR Series): $Z = \sqrt{R^2 + (X_L - X_C)^2}$. Phase Angle: $\tan\phi = \frac{X_L - X_C}{R}$. Power in AC Circuit: $P_{avg} = V_{rms}I_{rms}\cos\phi$. $\cos\phi$ is power factor. Resonance: $X_L = X_C \implies \omega_0 = \frac{1}{\sqrt{LC}}$. $Z = R$. Transformer: $\frac{V_s}{V_p} = \frac{N_s}{N_p} = \frac{I_p}{I_s}$ (ideal). Physics: Optics & Modern Physics Ray Optics & Optical Instruments Sign Convention: New Cartesian. Mirror Formula: $\frac{1}{f} = \frac{1}{v} + \frac{1}{u}$. Magnification: $m = -\frac{v}{u}$. Refraction (Snell's Law): $n_1 \sin i = n_2 \sin r$. Lens Maker's Formula: $\frac{1}{f} = (n_2 - n_1)\left(\frac{1}{R_1} - \frac{1}{R_2}\right)$. Lens Formula: $\frac{1}{f} = \frac{1}{v} - \frac{1}{u}$. Power of Lens: $P = \frac{1}{f}$ (in dioptres, f in meters). Combination of Lenses: $P = P_1 + P_2$, $\frac{1}{f} = \frac{1}{f_1} + \frac{1}{f_2}$. Total Internal Reflection: $\sin i_c = \frac{n_2}{n_1}$ ($n_1 > n_2$). Prism Formula: $n = \frac{\sin((A+\delta_m)/2)}{\sin(A/2)}$. Wave Optics Huygen's Principle: Explains wave propagation, reflection, refraction. Interference (Young's Double Slit): Path Difference: $\Delta x = d\sin\theta$. Bright Fringes: $\Delta x = n\lambda$. Dark Fringes: $\Delta x = (n + \frac{1}{2})\lambda$. Fringe Width: $\beta = \frac{\lambda D}{d}$. Diffraction (Single Slit): Minima: $a\sin\theta = n\lambda$. Maxima: $a\sin\theta = (n + \frac{1}{2})\lambda$. Central Maxima Width: $2\theta = \frac{2\lambda}{a}$. Polarization (Brewster's Law): $\tan i_p = n$. Dual Nature of Radiation & Matter Photon Energy: $E = h\nu = \frac{hc}{\lambda}$. Photoelectric Effect: $K_{max} = h\nu - \phi_0 = eV_0$. De Broglie Wavelength: $\lambda = \frac{h}{p} = \frac{h}{mv}$. For Electron: $\lambda = \frac{1.227}{\sqrt{V}}$ nm. Atoms & Nuclei Rutherford's Model: Nucleus at center, electrons orbit. Bohr's Model: Quantized orbits, stationary states, energy levels. Radius of $n^{th}$ orbit: $r_n = 0.529 n^2 / Z \text{ Å}$. Energy of $n^{th}$ orbit: $E_n = -13.6 Z^2 / n^2 \text{ eV}$. Atomic Spectra: Hydrogen series (Lyman, Balmer, Paschen, etc.). Nuclear Size: $R = R_0 A^{1/3}$. Nuclear Mass Defect: $\Delta m = [Zm_p + (A-Z)m_n] - M_{nucleus}$. Binding Energy: $E_b = \Delta m c^2$. Radioactivity: $N = N_0 e^{-\lambda t}$. Half-life: $T_{1/2} = \frac{\ln 2}{\lambda} = \frac{0.693}{\lambda}$. Mean Life: $\tau = \frac{1}{\lambda}$. Alpha Decay: $_Z^A X \to _{Z-2}^{A-4} Y + _2^4 He$. Beta Decay: $_Z^A X \to _{Z+1}^A Y + e^- + \bar{\nu}$ (beta minus). $_Z^A X \to _{Z-1}^A Y + e^+ + \nu$ (beta plus). Gamma Decay: Nucleus emits photon, no change in A or Z. Physics: Electronic Devices Semiconductors: Intrinsic (pure Si, Ge), Extrinsic (doped). N-type: Doped with Pentavalent (P, As) - majority electrons. P-type: Doped with Trivalent (B, Al) - majority holes. P-N Junction Diode: Forward bias (low resistance), Reverse bias (high resistance). Rectifiers: Half-wave, Full-wave (convert AC to DC). Zener Diode: Used as voltage regulator. Transistor (BJT): NPN, PNP. Acts as amplifier or switch. Current Gain: $\beta_{ac} = \frac{\Delta I_C}{\Delta I_B}$. Logic Gates: AND, OR, NOT, NAND, NOR, XOR, XNOR. Gate Symbol Boolean Expression AND $A \cdot B$ OR $A + B$ NOT $\bar{A}$ Chemistry: Solid State Types of Solids: Crystalline (definite geometry, sharp MP), Amorphous (irregular, gradual softening). Unit Cells: Simple Cubic (SC): 1 atom/unit cell, $r = a/2$. Body-Centered Cubic (BCC): 2 atoms/unit cell, $r = \sqrt{3}a/4$. Face-Centered Cubic (FCC): 4 atoms/unit cell, $r = \sqrt{2}a/4$. Packing Efficiency: SC (52.4%), BCC (68%), FCC/HCP (74%). Density: $\rho = \frac{ZM}{a^3 N_A}$. Voids: Tetrahedral (4 neighbors), Octahedral (6 neighbors). Defects: Stoichiometric: Schottky (missing cation/anion), Frenkel (ion occupies interstitial site). Non-Stoichiometric: Metal excess/deficiency. Magnetic Properties: Para-, Ferro-, Ferri-, Anti-ferromagnetism. Chemistry: Solutions Concentration Terms: Molarity (M): moles of solute / volume of solution (L). Molality (m): moles of solute / mass of solvent (kg). Mole Fraction ($\chi$): moles of component / total moles. Mass %: (mass of component / total mass) $\times 100$. Raoult's Law: $P_A = P_A^0 \chi_A$. For volatile components, $P_{total} = P_A^0 \chi_A + P_B^0 \chi_B$. Colligative Properties: Depend on number of solute particles, not their nature. Relative Lowering of Vapor Pressure: $\frac{P_A^0 - P_A}{P_A^0} = \chi_B$. Elevation in Boiling Point: $\Delta T_b = K_b m$. Depression in Freezing Point: $\Delta T_f = K_f m$. Osmotic Pressure: $\Pi = iCRT$. Van't Hoff Factor ($i$): For dissociation $i > 1$, for association $i Chemistry: Electrochemistry Electrochemical Cell: Converts chemical energy to electrical energy. Redox Reactions: Oxidation at anode, Reduction at cathode. Electrode Potential: Tendency of an electrode to lose/gain electrons. Standard Electrode Potential ($E^0$): Measured at 298 K, 1 atm, 1 M concentration. Nernst Equation: $E_{cell} = E_{cell}^0 - \frac{RT}{nF} \ln Q$. At 298 K, $E_{cell} = E_{cell}^0 - \frac{0.0591}{n} \log Q$. Gibbs Free Energy: $\Delta G^0 = -nFE_{cell}^0$. Relation with Equilibrium Constant: $\Delta G^0 = -RT \ln K_{eq}$. $E_{cell}^0 = \frac{RT}{nF} \ln K_{eq}$. Conductance: $G = \frac{1}{R}$. Unit: Siemens (S). Conductivity ($\kappa$): $\kappa = G \times \frac{l}{A}$. Unit: S cm$^{-1}$. Molar Conductivity ($\Lambda_m$): $\Lambda_m = \frac{\kappa \times 1000}{M}$. Unit: S cm$^2$ mol$^{-1}$. Kohlrausch's Law: $\Lambda_m^0 = \nu_+ \lambda_+^0 + \nu_- \lambda_-^0$. Faraday's Laws of Electrolysis: First Law: $m \propto Q = It$. Second Law: $\frac{m_1}{m_2} = \frac{E_1}{E_2}$. Chemistry: Chemical Kinetics Rate of Reaction: Change in concentration of reactant/product per unit time. Rate Law: Rate $= k[A]^x[B]^y$. Order of Reaction: Sum of powers of concentration terms ($x+y$). Molecularity: Number of reacting species in an elementary step. Integrated Rate Laws: Zero Order: $[A]_t = [A]_0 - kt$. $t_{1/2} = \frac{[A]_0}{2k}$. First Order: $\ln[A]_t = \ln[A]_0 - kt$. $t_{1/2} = \frac{0.693}{k}$. Arrhenius Equation: $k = A e^{-E_a/RT}$. $\ln k = \ln A - \frac{E_a}{RT}$. Activation Energy ($E_a$): Minimum energy required for reaction. Chemistry: Organic Chemistry Highlights Haloalkanes & Haloarenes Nomenclature: IUPAC naming. Preparation: From alcohols, hydrocarbons. Reactions: Nucleophilic Substitution: $S_N1$ (2 steps, carbocation, 3>2>1 alkyl halides), $S_N2$ (1 step, transition state, 1>2>3 alkyl halides). Elimination (Dehydrohalogenation): Saytzeff's rule (more substituted alkene). Reaction with Metals: Wurtz reaction, Grignard reagents. Haloarenes: Electrophilic substitution (ortho/para directing). Alcohols, Phenols & Ethers Alcohols: Preparation: From alkenes, carbonyl compounds, Grignard reagents. Reactions: Oxidation, dehydration, esterification, reaction with HX. Phenols: More acidic than alcohols due to resonance stabilization of phenoxide ion. Preparation: From haloarenes, benzene sulphonic acid, cumene. Reactions: Electrophilic substitution (Kolbe's, Reimer-Tiemann), oxidation. Ethers: Preparation: Williamson synthesis. Reactions: Cleavage by strong acids (HI, HBr). Aldehydes, Ketones & Carboxylic Acids Aldehydes & Ketones: Preparation: Oxidation of alcohols, ozonolysis of alkenes, hydration of alkynes. Reactions: Nucleophilic addition (HCN, Grignard, alcohols), reduction, oxidation, aldol condensation, Cannizzaro reaction. Carboxylic Acids: More acidic than phenols and alcohols. Preparation: Oxidation of primary alcohols/aldehydes, Grignard reagents, nitriles. Reactions: Esterification, formation of acid derivatives, Hell-Volhard-Zelinsky (HVZ) reaction. Amines Nomenclature & Classification: Primary, secondary, tertiary. Preparation: Reduction of nitro compounds, nitriles, amides (Hoffmann bromamide degradation). Basicity: Aliphatic amines > Ammonia > Aromatic amines. Affected by inductive and steric effects. Reactions: Acylation, alkylation, carbylamine reaction, reaction with nitrous acid (distinguishes 1°, 2°, 3° amines). Biology: Reproduction Reproduction in Organisms Asexual Reproduction: Single parent, offspring genetically identical (clones). Methods: Binary fission (Amoeba), Budding (Hydra, Yeast), Fragmentation (Spirogyra), Spore formation (Fungi), Vegetative propagation (plants: runners, rhizomes, tubers, bulbs). Sexual Reproduction: Two parents, involves gamete formation and fusion, offspring genetically different. Phases: Juvenile/Vegetative phase, Reproductive phase, Senescence phase. Events: Pre-fertilisation (gametogenesis, gamete transfer), Fertilisation (syngamy), Post-fertilisation (zygote formation, embryogenesis). Sexual Reproduction in Flowering Plants Flower Structure: Sepals, Petals, Stamens (anther, filament), Pistil/Carpel (stigma, style, ovary). Microsporangium (Pollen Sac): Produces pollen grains (male gametophyte). Megasporangium (Ovule): Contains embryo sac (female gametophyte). Pollination: Transfer of pollen to stigma. Agents: Wind, water, insects, animals. Types: Autogamy (same flower), Geitonogamy (same plant, different flower), Xenogamy (different plant). Double Fertilisation: One male gamete fuses with egg cell (syngamy), other fuses with central cell (triple fusion). Forms zygote and primary endosperm nucleus (PEN). Post-fertilisation Changes: Ovule $\to$ Seed, Ovary $\to$ Fruit. Human Reproduction Male Reproductive System: Testes (sperm, testosterone), Epididymis, Vas deferens, Seminal vesicles, Prostate gland, Bulbourethral glands, Urethra, Penis. Female Reproductive System: Ovaries (ova, hormones), Oviducts (fallopian tubes), Uterus, Cervix, Vagina, External genitalia. Gametogenesis: Spermatogenesis: Formation of sperm in testes. Oogenesis: Formation of ovum in ovaries. Menstrual Cycle: 28-day cycle. Phases: Menstrual, Follicular (proliferative), Ovulatory, Luteal (secretory). Hormonal control (GnRH, LH, FSH, Estrogen, Progesterone). Fertilisation & Implantation: Fusion of sperm and ovum in fallopian tube. Zygote forms, cleaves, forms blastocyst, implants in uterine wall. Pregnancy & Embryonic Development: Gestation period (approx 9 months). Placenta formation, organogenesis. Parturition & Lactation: Childbirth, milk production. Reproductive Health Family Planning Methods: Natural: Periodic abstinence, withdrawal. Barrier: Condoms, diaphragms. IUDs: Copper-T, Lippes loop. Oral Contraceptives: Pills. Surgical: Vasectomy (male), Tubectomy (female). STIs (Sexually Transmitted Infections): Gonorrhea, Syphilis, Genital herpes, Chlamydiosis, AIDS. Infertility: Assisted Reproductive Technologies (ART): IVF, ZIFT, GIFT, ICSI. Biology: Genetics & Evolution Principles of Inheritance & Variation Mendel's Laws: Law of Dominance: Dominant allele expresses in heterozygote. Law of Segregation: Alleles separate during gamete formation. Law of Independent Assortment: Genes for different traits assort independently. Monohybrid Cross: Phenotypic ratio 3:1, Genotypic ratio 1:2:1. Dihybrid Cross: Phenotypic ratio 9:3:3:1. Incomplete Dominance: Heterozygote shows intermediate phenotype (e.g., snapdragon flower color). Co-dominance: Both alleles express fully (e.g., ABO blood groups). Sex Determination: XX-XY (humans), ZZ-ZW (birds), XO (insects). Linkage: Genes on same chromosome inherit together. Crossing Over: Exchange of genetic material between homologous chromosomes. Pedigree Analysis: Study of inheritance pattern in families. Genetic Disorders: Mendelian disorders (e.g., Haemophilia, Sickle cell anemia, Phenylketonuria), Chromosomal disorders (e.g., Down's syndrome, Klinefelter's, Turner's). Molecular Basis of Inheritance DNA Structure: Double helix (Watson & Crick). Deoxyribose sugar, phosphate, nitrogenous bases (A, T, C, G). A pairs with T (2 H-bonds), C pairs with G (3 H-bonds). DNA Replication: Semi-conservative (Meselson & Stahl experiment). Transcription: DNA $\to$ mRNA (RNA polymerase). Genetic Code: Triplet, degenerate, unambiguous, universal. Translation: mRNA $\to$ Protein (Ribosomes, tRNA, amino acids). Gene Regulation: Lac Operon (Jacob & Monod). Human Genome Project (HGP): Sequenced entire human genome. DNA Fingerprinting: Uses VNTRs (Variable Number of Tandem Repeats). Evolution Origin of Life: Oparin-Haldane theory, Miller's experiment. Evidences of Evolution: Paleontology, comparative anatomy, embryology, molecular homology. Homologous Organs: Similar structure, different function (e.g., forelimbs of whale, bat, human). Analogous Organs: Different structure, similar function (e.g., wings of insect, bird). Adaptive Radiation: Diversification from common ancestor (e.g., Darwin's finches). Hardy-Weinberg Principle: Genetic equilibrium, $p^2 + 2pq + q^2 = 1$. Factors affecting: gene flow, genetic drift, mutation, recombination, natural selection. Types of Natural Selection: Stabilizing, Directional, Disruptive. Human Evolution: Dryopithecus $\to$ Ramapithecus $\to$ Homo habilis $\to$ Homo erectus $\to$ Homo sapiens. Biology: Biology in Human Welfare Human Health & Disease Pathogens: Bacteria, Viruses, Fungi, Protozoa, Helminths. Common Diseases: Bacterial: Typhoid, Pneumonia. Viral: Common cold, AIDS, Dengue, Chikungunya. Protozoan: Malaria (Plasmodium), Amoebiasis (Entamoeba), Ascariasis (Ascaris). Fungal: Ringworm. Immunity: Innate: Non-specific, present from birth (physical barriers, cellular barriers, cytokines). Acquired: Specific, pathogen-specific (primary & secondary response). Humoral (Antibody-mediated): B-lymphocytes. Cell-mediated: T-lymphocytes. Vaccination & Immunisation: Active (body produces antibodies), Passive (readymade antibodies given). AIDS (Acquired ImmunoDeficiency Syndrome): Caused by HIV. Attacks helper T-cells. Cancer: Uncontrolled cell proliferation. Benign (localized), Malignant (metastasis). Drug & Alcohol Abuse: Opioids, Cannabinoids, Cocaine. Adverse effects. Microbes in Human Welfare Household Products: Lactic Acid Bacteria (LAB) for curd, Yeast for bread/fermentation. Industrial Products: Fermented Beverages: Wine, beer, whisky, brandy, rum (Yeast). Antibiotics: Penicillin (Penicillium notatum). Chemicals: Citric acid (Aspergillus niger), Acetic acid (Acetobacter aceti), Butyric acid (Clostridium butylicum). Enzymes: Lipases (detergents), Pectinases, Proteases (clear fruit juices), Streptokinase (clot buster). Bioactive Molecules: Cyclosporin A (immunosuppressant), Statins (cholesterol lowering). Sewage Treatment: Primary (physical removal), Secondary (biological treatment by microbes). Biogas Production: Anaerobic digestion by methanogens (Methane, CO2, H2). Biocontrol Agents: Bacillus thuringiensis (Bt) for insect pests, Trichoderma (fungal diseases), Baculoviruses. Biofertilisers: Bacteria (Rhizobium, Azotobacter, Azospirillum), Fungi (Mycorrhiza), Cyanobacteria (Anabaena, Nostoc). Biology: Biotechnology Biotechnology: Principles & Processes Genetic Engineering: Manipulation of genetic material to introduce into host. Key Steps: Isolation of DNA. Fragmentation of DNA (Restriction enzymes - molecular scissors). Ligation of DNA fragment into vector (DNA ligase). Insertion of recombinant DNA into host. Culturing host cells. Extraction of desired product. Cloning Vector: Plasmid. Features: Ori, Selectable marker, Cloning sites. PCR (Polymerase Chain Reaction): Amplifies DNA using primers, Taq polymerase. Steps: Denaturation, Annealing, Extension. Bioreactors: Large vessels for culturing cells to obtain products. Biotechnology & Its Applications Bt Cotton: Expresses Cry gene from Bacillus thuringiensis, produces protein toxic to insect pests. Pest Resistant Plants: RNA interference (RNAi) in tobacco against nematode. Genetically Engineered Insulin: Humulin (Eli Lilly). A and B chains produced separately, joined by disulfide bonds. Gene Therapy: SCID treatment using ADA (Adenosine Deaminase) enzyme replacement. Molecular Diagnosis: ELISA, PCR for early detection of diseases. Transgenic Animals: Produce useful biological products, vaccine safety testing. Ethical Issues: GEAC (Genetic Engineering Approval Committee). Biology: Ecology Organisms & Populations Organism & Environment: Abiotic factors (temperature, water, light, soil). Responses to Abiotic Factors: Regulate, Conform, Migrate, Suspend (Hibernation, Aestivation, Diapause). Adaptations: Morphological, Physiological, Behavioral. Population Attributes: Birth rate, Death rate, Sex ratio, Age distribution. Population Growth Models: Exponential: $dN/dt = (b-d)N = rN$. Logistic: $dN/dt = rN(K-N)/K$. (K = carrying capacity). Population Interactions: Mutualism: (+,+) e.g., Lichens. Competition: (-,-) e.g., Warblers. Predation: (+,-) e.g., Tiger & Deer. Parasitism: (+,-) e.g., Ticks on dogs. Commensalism: (+,0) e.g., Orchid on mango branch. Amensalism: (-,0) e.g., Penicillium & bacteria. Ecosystem Ecosystem Structure & Function: Productivity, Decomposition, Energy Flow, Nutrient Cycling. Productivity: GPP (Gross Primary Productivity), NPP (Net Primary Productivity = GPP - Respiration). Decomposition: Fragmentation, Leaching, Catabolism, Humification, Mineralisation. Energy Flow: Unidirectional. 10% Law (Lindeman). Ecological Pyramids: Number, Biomass, Energy (always upright, except for biomass in aquatic). Nutrient Cycling: Carbon cycle, Phosphorus cycle. Ecological Succession: Primary (bare area), Secondary (disturbed area). Biodiversity & Conservation Biodiversity: Genetic, Species, Ecological diversity. Patterns of Biodiversity: Latitudinal gradients, Species-Area relationship ($S = CA^Z$). Loss of Biodiversity: Habitat loss & fragmentation, Over-exploitation, Alien species invasions, Co-extinctions. Biodiversity Conservation: In situ: National Parks, Wildlife Sanctuaries, Biosphere Reserves, Sacred Groves. Ex situ: Zoological Parks, Botanical Gardens, Wildlife Safari Parks, Seed Banks, Gene Banks. Environmental Issues Air Pollution: Particulates, SO2, NOx. Effects, control measures (Electrostatic precipitator, Scrubber). Water Pollution: Domestic sewage, industrial wastes. BOD (Biochemical Oxygen Demand), Eutrophication, Biomagnification. Solid Wastes: Municipal solid waste, E-waste. Recycling, Incineration. Radioactive Waste: Disposal challenges. Greenhouse Effect & Global Warming: CO2, CH4, N2O, CFCs. Consequences. Ozone Depletion: CFCs in stratosphere. Ozone hole, UV radiation effects. Deforestation: Causes, consequences. Reforestation.