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 ✍️ Chapter 11: Biotechnology: Principles and Processes --- 🔶 Introduction to Biotechnology Biotechnology is the branch of biology that deals with the use of living organisms and biological systems to develop products and technologies for human use. Modern biotechnology involves genetic engineering and bioprocess engineering. --- 🔷 Principles of Biotechnology There are two core techniques that enabled the growth of modern biotechnology: 1. Genetic Engineering – Altering the chemistry of genetic material (DNA/RNA) to introduce desirable traits. 2. Bioprocess Engineering – Maintenance of sterile conditions to allow growth of only the desired microbe. --- 🧬 Tools of Recombinant DNA Technology 1. Restriction Enzymes (Molecular Scissors) Cut DNA at specific sites called recognition sequences. Example: EcoRI – Cuts between G and A in GAATTC. Types: Exonucleases – Remove nucleotides from ends. Endonucleases – Cut within the DNA. 📌 Diagram: Action of Restriction Endonuclease on DNA ---...

 🧬 Chapter 7: Evolution – Class 12 Biology Notes 🔹 Introduction Evolution refers to the gradual changes occurring in living organisms over millions of years. It explains the origin of new species from pre-existing ones through various mechanisms like mutation, natural selection, genetic drift, etc. --- 🔹 Origin of Life Big Bang Theory: Universe originated about 20 billion years ago. Early Earth: Formed around 4.5 billion years ago; no oxygen, only methane, ammonia, hydrogen, water vapor. Chemical Evolution: Life began from non-living molecules (Oparin-Haldane theory). Miller-Urey Experiment: Simulated early Earth conditions and created organic molecules (amino acids). 📌 Important Diagram: Miller and Urey's Experiment Setup --- 🔹 Theories of Evolution 1. Lamarckism: Proposed by Jean Baptiste Lamarck. Theory of Inheritance of Acquired Characters. Example: Giraffe's long neck. 2. Darwinism (Natural Selection): Proposed by Charles Darwin. Survival of the fittest. Based on: Var...

  📚 Chapter: Molecular Basis of Inheritance – Detailed Notes --- 🔸 1. Introduction This chapter explains how genetic information is stored, replicated, and expressed in living organisms through DNA and RNA. --- 🔹 2. DNA – The Genetic Material Full form: Deoxyribonucleic Acid Found in nucleus (eukaryotes), cytoplasm (prokaryotes) Proved by: ✅ Griffith's Transformation Experiment ✅ Avery-MacLeod-McCarty experiment ✅ Hershey-Chase experiment (Bacteriophage with radioactive sulfur and phosphorus) --- 🔹 3. Structure of DNA Double helix model by Watson and Crick Each nucleotide = phosphate + deoxyribose sugar + nitrogenous base Nitrogenous bases: Purines: Adenine (A), Guanine (G) Pyrimidines: Cytosine (C), Thymine (T) Base pairing: A = T (2 H-bonds), G ≡ C (3 H-bonds) Antiparallel strands (5′ → 3′ and 3′ → 5′) --- 🔹 4. Packaging of DNA In prokaryotes: Looped and held by non-histone proteins In eukaryotes: Histone proteins form nucleosomes – "Beads on string" structure --- ...

 📚 Chapter: Principles of Inheritance and Variation – Class 12 Biology Notes --- 🔸 1. Introduction Genetics is the branch of biology that deals with heredity and variation. Heredity: Transmission of characters from parents to offspring Variation: Differences among individuals --- 🔹 2. Mendel and His Experiments Gregor Mendel is known as Father of Genetics He worked on garden pea (Pisum sativum) He selected 7 contrasting traits like tall/dwarf, round/wrinkled etc. --- 🔹 3. Mendel’s Laws of Inheritance a) Law of Dominance Dominant allele expresses itself in F₁ generation b) Law of Segregation Alleles separate during gamete formation c) Law of Independent Assortment Genes for different traits assort independently --- 🔹 4. Monohybrid Cross One trait considered Genotypic ratio: 1:2:1 Phenotypic ratio: 3:1 --- 🔹 5. Dihybrid Cross Two traits considered Phenotypic ratio: 9:3:3:1 --- 🔹 6. Incomplete Dominance F₁ is intermediate Example: Red × White flower = Pink (in Snapdragon) --- ?...

 📚 Chapter: Reproductive Health – Class 12 Biology Notes --- 🔸 Introduction: Reproductive health means a complete physical, emotional, and social well-being in all aspects of reproduction. It includes awareness, safe practices, and control over fertility. --- 🔹 1. Need for Reproductive Health To prevent sexually transmitted infections (STIs) To reduce maternal and infant mortality To control population growth To educate people about sex and contraception --- 🔹 2. Reproductive Health Programmes in India Started in 1951 (RCH Programme) Objectives: Family planning Safe motherhood Adolescent health Prevention of STDs --- 🔹 3. Birth Control Methods a) Natural Methods: Rhythm method (safe period) Withdrawal Lactational Amenorrhea (up to 6 months) b) Barrier Methods: Condoms (male & female) Diaphragms, Cervical caps c) Intrauterine Devices (IUDs): Non-medicated (Lippes loop) Copper releasing (Cu-T) Hormone releasing (Progestasert) d) Oral Contraceptives: Pills containing estrogen...

 📚 Chapter: Human Reproduction – Class 12 Biology Notes --- 🔸 Introduction: Human reproduction is sexual reproduction involving the fusion of male and female gametes. This chapter covers reproductive organs, gamete formation, menstrual cycle, fertilisation and pregnancy. --- 🔹 1. Male Reproductive System Primary organs: Testes (sperm production) Accessory ducts: Epididymis, Vas deferens, Urethra Glands: Seminal vesicles, Prostate, Bulbourethral External genitalia: Penis Spermatogenesis: Formation of sperm in seminiferous tubules Hormone control: FSH, LH, Testosterone --- 🔹 2. Female Reproductive System Primary organs: Ovaries (ovum production) Ducts: Fallopian tubes, Uterus, Cervix, Vagina External genitalia: Vulva Oogenesis: Formation of ovum Hormone control: Estrogen, Progesterone, FSH, LH --- 🔹 3. Menstrual Cycle Average duration: 28 days Phases: 1. Menstrual phase (1-5 days) 2. Follicular phase (6–13 days) 3. Ovulation (Day 14) 4. Luteal phase (15–28 days) Controlled by ho...

 🌸 Chapter 2: Sexual Reproduction in Flowering Plants – Class 12 Biology Notes Label: Biology, Class 12, Reproduction --- 🔹 Introduction Plants reproduce sexually through flowers, which are the reproductive organs. The process includes gamete formation, pollination, fertilization, and seed formation. --- 🌼 Structure of a Flower A flower has four main whorls: 1. Calyx (sepals) – Protect the bud 2. Corolla (petals) – Attract pollinators 3. Androecium (stamens) – Male reproductive part 4. Gynoecium (carpels) – Female reproductive part --- ♂️ Stamen (Male Reproductive Organ) Made up of: Anther – Bilobed, pollen-producing Filament – Stalk holding anther 📍 Microsporangium: Inside anther, contains pollen sacs Forms pollen mother cells (PMCs) → undergo meiosis → pollen grains 📍 Microsporogenesis: Formation of microspores (pollen grains) from PMCs via meiosis Each microspore develops into a male gametophyte --- ♀️ Gynoecium (Female Reproductive Organ) Made up of: Stigma – Receives poll...

 🌸 Chapter 2: Sexual Reproduction in Flowering Plants – Class 12 Biology Notes Label: Biology, Class 12, Reproduction --- 🔹 Introduction Reproduction in angiosperms (flowering plants) occurs through sexual reproduction involving flowers, gametes, and fertilization. --- 🌼 Parts of a Typical Flower Part Description Sepals (Calyx) Protects flower in bud stage Petals (Corolla) Bright coloured, attract pollinators Stamens (Androecium) Male reproductive part (Anther + Filament) Carpels (Gynoecium) Female reproductive part (Ovary + Style + Stigma) --- 🧬 Pre-fertilization Events 1. Development of Male Gametophyte Microsporogenesis: Formation of microspores (pollen grains) in anther by meiosis Microspore → Pollen mother cell → Pollen grains Mature pollen: 2 cells – Generative cell & Vegetative cell 2. Development of Female Gametophyte Ovule develops inside ovary Megaspore mother cell → Meiosis → 4 megaspores (1 functional) Embryo sac (female gametophyte): 7 cells, 8 nuclei 1 Egg cel...

 📌 What is Reproduction? Reproduction is the biological process by which living organisms produce offspring similar to themselves. Types of Reproduction: 1. Asexual Reproduction – Single parent, no gamete involvement. Examples: Binary Fission (Amoeba), Budding (Hydra) 2. Sexual Reproduction – Two parents, gamete formation, and fusion. Involves male and female reproductive systems. --- 🧪 Lifespans of Organisms: Defined as the period between birth and natural death. Mayfly: 1 day Elephant: 60–70 years Tortoise: 100–150 years --- 🌱 Asexual Reproduction Methods: Method Example Binary Fission Amoeba Budding Hydra, Yeast Fragmentation Spirogyra Spore Formation Rhizopus Vegetative Potato, Ginger --- 👫 Sexual Reproduction Stages: 1. Pre-fertilization Events Gametogenesis Gamete Transfer 2. Fertilization Fusion of male and female gametes (zygote formation) 3. Post-fertilization Events Zygote development Embryogenesis --- 🧬 Important Terms: Zygote: Single-celled formed after fertilizati...