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 🌸 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...