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BiologyClass 12CBSE
What Stops More Than One Sperm From Entering an Egg
Follow fertilisation with the acrosomal and cortical reactions and sex determination, trace cleavage to the blastocyst and implantation, understand the placenta's hormones and the landmarks of pregnancy, and explain parturition and lactation.
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Why Sperm Come in Fours but Eggs Come Alone
Trace spermatogenesis and its control by GnRH, LH and FSH, describe the structure of a sperm and the composition of semen, follow oogenesis through the follicle stages, and link each phase of the menstrual cycle to its hormones.
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Why the Testes Sit Outside the Body
Trace the organs, ducts and accessory glands of the male reproductive system, explore the seminiferous tubules and their Sertoli and Leydig cells, describe the female reproductive organs, and study the microscopic ovary and the mammary gland.
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Why a Coconut Holds Both Liquid and Solid Endosperm
Compare free-nuclear and cellular endosperm and albuminous and non-albuminous seeds, name the parts of dicot and monocot embryos, see how ovules and ovaries become seeds and fruits, and understand apomixis, polyembryony and parthenocarpy.
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Why Some Flowers Refuse Their Own Pollen
Classify pollination as autogamy, geitonogamy and xenogamy, match pollinating agents with floral adaptations, explain the devices that prevent self-pollination and the steps of artificial hybridisation, and follow pollen-pistil interaction to double fertilisation.
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How a Flower Makes Pollen and an Embryo Sac
Relate the parts of a flower to gametophyte development, trace microsporogenesis inside the microsporangium, explore the structure and viability of pollen grains, and follow megasporogenesis from the ovule to the 7-celled, 8-nucleate embryo sac.
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Why Boiling an Egg Changes Its Proteins Forever
Classify amino acids and explain zwitterions and peptide bonds, describe the four levels of protein structure and denaturation, understand enzymes and vitamins with their deficiency diseases, and compare DNA and RNA and the roles of hormones.
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Why Table Sugar Fails the Test That Glucose Passes
Classify carbohydrates by size, carbonyl type and reducing power, work through the open-chain and ring structures of glucose and fructose with anomers, compare sucrose, maltose and lactose, and contrast starch, cellulose and glycogen.
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How Aniline Becomes the Colour in Your Clothes
Compare the basic strength of aliphatic and aromatic amines, use the carbylamine and Hinsberg tests, explain substitution in aniline and why Friedel-Crafts fails, and turn benzenediazonium chloride into halides, phenols and azo dyes.
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Why Stale Fish Smells the Way It Does
Understand the pyramidal structure, classification and naming of amines, prepare them by reduction and ammonolysis, make pure primary amines by Gabriel synthesis and Hoffmann bromamide degradation, and explain their boiling points and solubility.
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Why Vinegar Fizzes With Baking Soda but Alcohol Does Not
Name carboxylic acids and see why the carboxylate ion is resonance-stabilised, prepare acids by several routes, compare their acidity with phenols and alcohols including substituent effects, and follow their reactions from esters to decarboxylation and HVZ.
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How a Silver Mirror Reveals an Aldehyde
Understand nucleophilic addition to the carbonyl group and why aldehydes outpace ketones, work through additions of HCN, alcohols, ammonia derivatives and Grignard reagents, reductions and Tollens' and Fehling's tests, and aldol and Cannizzaro reactions.
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How Chemists Stop an Oxidation Exactly at the Aldehyde
Name aldehydes and ketones and understand the polar carbonyl group, prepare them from alcohols, alkenes and alkynes, make aldehydes selectively by the Rosenmund, Stephen, Etard and Gatterman-Koch reactions, and compare their physical properties.
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Why Phenol Is Acidic but Ethanol Is Not
Prepare phenol from haloarenes, benzenesulphonic acid, diazonium salts and cumene, explain its acidity and substituent effects, study its substitution, Kolbe and Reimer-Tiemann reactions, and prepare ethers and follow their reactions.
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Why Alcohols Boil So Much Higher Than Similar Hydrocarbons
Classify and name alcohols, phenols and ethers, prepare alcohols from alkenes, carbonyl compounds and Grignard reagents, explain their boiling points and solubility, and use their key reactions with the Lucas test.
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Why Some Reactions Flip a Molecule Inside Out Like an Umbrella
Contrast SN1 and SN2 substitution, predict inversion or racemisation using chirality, apply Saytzeff's rule with the Wurtz and Grignard reactions, and explain why haloarenes resist nucleophiles along with the uses and hazards of polyhalogen compounds.
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How Swapping One Hydrogen for a Halogen Transforms a Molecule
Classify and name haloalkanes and haloarenes, understand the polarity, length and strength of the carbon-halogen bond, and prepare halogen compounds from alcohols, hydrocarbons, halogen exchange and diazonium salts, with their physical properties.
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Why Ruby Is Red and Emerald Is Green
Predict hybridisation, shape and magnetism with valence bond theory, use crystal field splitting and the spectrochemical series to decide high or low spin, explain colour and magnetism, and understand synergic bonding in metal carbonyls and uses of complexes.
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Why Some Salts Keep Their Ions Locked Inside a Complex
Use Werner's theory to tell primary from secondary valence and double salts from coordination compounds, master the vocabulary of ligands and coordination number, write IUPAC names and formulas, and identify structural and stereoisomers of complexes.
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Why Purple Permanganate Turns Colourless in Acid
Learn the preparation, structure and oxidising reactions of potassium dichromate and potassium permanganate, see how pH controls the chromate-dichromate balance, and compare the lanthanoids and actinoids, including lanthanoid contraction and its consequences.
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Why Copper Sulphate Is Blue but Zinc Sulphate Is White
Place the d- and f-block elements in the periodic table and write their configurations with the chromium and copper exceptions, explain the physical properties of transition metals, and account for their oxidation states, colour, magnetism and catalysis.
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Why Some Reactions Always Take the Same Time to Halve
Derive and use the integrated rate equations for zero and first order reactions, including gas-phase and pseudo first order reactions, calculate half-lives, and apply the Arrhenius equation and collision theory to temperature and catalysts.
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Why Milk Sours Faster on a Hot Summer Day
Express reaction rates as average and instantaneous values, deduce rate laws and orders from experimental data with the units of the rate constant, tell order from molecularity, and see how concentration, temperature and catalysts change the rate.
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Why Iron Rusts Faster Near the Sea
Compare primary and secondary batteries through the dry cell, mercury cell, lead storage battery and nickel-cadmium cell, see how a hydrogen-oxygen fuel cell works, and explain the corrosion of iron and the ways to prevent it.
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