Skip to main content
UploadLanguage (EN)Support
BusinessMobileSocial MediaMarketingTechnologyArt & PhotosCareerDesignEducationPresentations & Public SpeakingGovernment & NonprofitHealthcareInternetLawLeadership & ManagementAutomotiveEngineeringSoftwareRecruiting & HRRetailSalesServicesScienceSmall Business & EntrepreneurshipFoodEnvironmentEconomy & FinanceData & AnalyticsInvestor RelationsSportsSpiritualNews & PoliticsTravelSelf ImprovementReal EstateEntertainment & HumorHealth & MedicineDevices & HardwareLifestyle
SS
Uploaded bySandeep Swamy
5,627 views

Chapter-11-Reproduction-How-Life-Continues.pdf/ppt/Grade 9 Science | NCERT Curiosity Series // Prepared by K Sandeep Swamy (M.Sc, B.Ed) // subscribe Samyans Eduhub channel //for online classes contact 9491878325

Chapter 11: Reproduction — How Life Continues Grade 9 Science | NCERT Curiosity Series Prepared by K Sandeep Swamy (M.Sc, B.Ed) subscribe Samyans Eduhub channel for online classes contact 9491878325 Part 1 Asexual Reproduction How a single parent gives rise to genetically identical offspring — fast, efficient, and everywhere in nature. What is Reproduction? Reproduction is the biological process by which living organisms produce new individuals of the same kind — ensuring life continues on Earth. Accumulated variation over generations helps species adapt and can give rise to new species. Asexual Reproduction Single parent; offspring are genetically identical (clones) Sexual Reproduction Two parents; offspring inherit a mix of traits, creating variation Vegetative Propagation in Plants New plants arise from vegetative (growing) parts — roots, stems, or leaves — without seeds. Only one parent is involved, so offspring are genetically identical. Underground Stems Potato & ginger Stem Cuttings Money plant & sugarcane Leaf Plantlets Bryophyllum Agricultural Methods of Vegetative Propagation Cutting Shoot sections inserted into soil at 45°–60°; roots develop from nodes Grafting Stem of one plant (Plant B) inserted into a slit of another (Plant A); combines desirable traits — e.g., different rose varieties Layering Middle part of a twig buried in soil; roots develop in 10–15 days, then cut free Tissue Culture Mass-produces healthy plantlets from shoot tips; eliminates virus-infected plants (e.g., banana farming) Budding in Yeast and Hydra Yeast (Unicellular) Small round outgrowths (buds) emerge from parent cells and separate to form new individuals. Hydra (Multicellular) Repeated cell division at a specific site produces a bud that enlarges and separates to live independently. Multiple buds can grow simultaneously. Budding is a form of asexual reproduction where offspring grow directly from the parent body. Spore Formation in Fungi Fungi such as Rhizopus and Aspergillus reproduce by forming spores in sac-like structures on hyphae. Lightweight & Single-celled Spores float through air easily Rapid Germination Germinate when moisture and nutrients are available Millions Per Colony Highly efficient strategy for rapid population growth The Science Behind Asexual Reproduction: Mitosis Mitosis Cell division producing two daughter cells with the same number of chromosomes as the parent Clones Offspring are genetically identical to the parent — fast and efficient reproduction Population Boom Helps organisms increase population quickly when conditions are favourable Part 2 Sexual Reproduction Two parents, meiosis, gametes, and the power of genetic variation — how plants and animals mix traits across generations. Meiosis: Creating Variation Through Gametes Sexual reproduction requires two parents. To prevent chromosome numbers doubling each generation, meiosis halves the chromosome count. Gametes Haploid c

Education◦
Downloaded 535 times
Chapter 11: Reproduction — How Life Continues Grade 9 Science | NCERT Curiosity Series PREPARED BY K SANDEEP SWAMY (M.SC, B.ED) SUBSCRIBE SAMYANS EDUHUB CHANNEL FOR ONLINE CLASSES CONTACT 9491878325
Part 1 Asexual Reproduction How a single parent gives rise to genetically identical offspring — fast, efficient, and everywhere in nature.
What is Reproduction? Reproduction is the biological process by which living organisms produce new individuals of the same kind — ensuring life continues on Earth. Accumulated variation over generations helps species adapt and can give rise to new species. Asexual Reproduction Single parent; offspring are genetically identical (clones) Sexual Reproduction Two parents; offspring inherit a mix of traits, creating variation
Vegetative Propagation in Plants New plants arise from vegetative (growing) parts — roots, stems, or leaves — without seeds. Only one parent is involved, so offspring are genetically identical. Underground Stems Potato & ginger Stem Cuttings Money plant & sugarcane Leaf Plantlets Bryophyllum
Agricultural Methods of Vegetative Propagation 1 Cutting Shoot sections inserted into soil at 45°360°; roots develop from nodes 2 Grafting Stem of one plant (Plant B) inserted into a slit of another (Plant A); combines desirable traits 4 e.g., different rose varieties 3 Layering Middle part of a twig buried in soil; roots develop in 10315 days, then cut free 4 Tissue Culture Mass-produces healthy plantlets from shoot tips; eliminates virus- infected plants (e.g., banana farming)
Budding in Yeast and Hydra Yeast (Unicellular) Small round outgrowths (buds) emerge from parent cells and separate to form new individuals. Hydra (Multicellular) Repeated cell division at a specific site produces a bud that enlarges and separates to live independently. Multiple buds can grow simultaneously. Budding is a form of asexual reproduction where offspring grow directly from the parent body.
Spore Formation in Fungi Fungi such as Rhizopus and Aspergillus reproduce by forming spores in sac- like structures on hyphae. Lightweight & Single-celled Spores float through air easily Rapid Germination Germinate when moisture and nutrients are available Millions Per Colony Highly efficient strategy for rapid population growth
The Science Behind Asexual Reproduction: Mitosis Mitosis Cell division producing two daughter cells with the same number of chromosomes as the parent Clones Offspring are genetically identical to the parent — fast and efficient reproduction Population Boom Helps organisms increase population quickly when conditions are favourable
Part 2 Sexual Reproduction Two parents, meiosis, gametes, and the power of genetic variation — how plants and animals mix traits across generations.
Meiosis: Creating Variation Through Gametes Sexual reproduction requires two parents. To prevent chromosome numbers doubling each generation, meiosis halves the chromosome count. Gametes Haploid cells — sperm & eggs in animals; pollen & egg cells in plants Humans: 46 →23 Body cells have 46 chromosomes; each gamete carries 23 — random mixing creates millions of unique combinations
Parts of a Flower Male Organ — Stamen Filament + anther; anther produces pollen grains containing male gametes Female Organ — Pistil Stigma (sticky tip) + style (tube) + ovary (contains ovules with egg cells) Supporting Structures Sepals protect the bud; petals attract pollinators Flowers are the reproductive organs of angiosperms (flowering plants).
Pollination: Self and Cross Pollination is the transfer of pollen from anther to stigma — essential for fruit and seed formation. Self-Pollination Pollen transferred to the stigma of the same flower or same plant Cross-Pollination Pollen transferred from one plant to the stigma of another plant of the same species — promotes genetic variation
Pollination Strategies and Pollinators Wind Wheat, maize, rice — light, small pollen; long feathery stigma to trap grains Water Vallisneria and Hydrilla — water currents carry pollen Insects Sunflower, hibiscus, marigold — brightly coloured, fragrant, nectar-producing; sticky/spiny pollen Birds Coral tree, hibiscus — pollinated by Indian white-eye and sunbirds
Fertilisation and Fruit Formation Pollen Arrival Pollen lands on the stigma Fertilisation Male gamete fuses with egg → zygote and embryo Pollen Tube Growth Tube grows down through the style to ovary The ovary develops into the fruit; ovules develop into seeds containing the embryo.
Seed Dispersal and Germination How Seeds Travel Wind: Dandelion — fluffy pappus carries seeds aloft Water: Coconut — buoyant husks float on currents Animals: Burrs attach to fur; fruits eaten and seeds excreted Germination Conditions Water, air, and suitable temperature trigger a seed to sprout and grow into a new plant. Sexual reproduction creates variation — helping plant species survive and adapt to changing environments.
Part 3 Sexual Reproduction in Animals From fish releasing thousands of eggs to mammals nurturing young inside the womb — the diversity of animal reproduction strategies.
External vs. Internal Fertilisation External Fertilisation Frogs & most fish — eggs and sperm released into water. Large numbers of eggs produced, but many lost to predators or currents. Internal Fertilisation Reptiles, birds, mammals — fertilisation inside the female body. Fewer eggs, but much higher survival rate. Larvae (caterpillars, tadpoles) serve as a feeding stage before transformation into adults.
Variation in Animal Reproductive Strategies Animal Fertilisation No. of Eggs Offspring Survival Fish External 100s–1,000s Low Frog External 5,000–50,000 Low Lizard Internal 2–20 Moderate Bird Internal 1–15 Moderate–High Mammal Internal 1–few High (nourished in womb; fed via breast milk) The trade-off is clear: fewer eggs + more parental care = higher survival rate.
Part 4 Reproduction in Human Beings Puberty, gametes, fertilisation, pregnancy, and childbirth — the complete human reproductive journey.
The Male Reproductive System 01 Testes Produce sperm in the scrotum (slightly cooler than body temperature — essential for sperm formation); also produce male hormones 02 Vas Deferens Carries sperm from testes to the urethra 03 Seminal Vesicles & Prostate Add fluids to nourish and activate sperm Each sperm: head (genetic material) + long tail (for swimming)
The Female Reproductive System Ovaries Produce eggs (female gametes) and female hormones Fallopian Tubes (Oviducts) Connect ovaries to the uterus; site of fertilisation Uterus Bag-like structure where the foetus develops over ~9 months Cervix & Vagina Narrow passage and birth canal
Fertilisation and Implantation in Humans Implantation Mitotic divisions Fertilisation Ovulation From puberty, one mature egg is released monthly from an ovary — this is ovulation. Millions of sperm swim through the tract, but only one fuses with the egg.
The Menstrual Cycle If the egg is not fertilised, the thickened uterine lining sheds 4 this is menstruation (lasts 337 days). 28 Days Typical cycle length (range: 21335 days) ~50 Age (Menopause) Cycle begins at puberty (ages 10314) and continues until ~age 50
Pregnancy and Childbirth 1 1st Trimester (Months 1–3) Fertilised egg → embryo; major organs begin forming; called a foetus from week 9 2 2nd Trimester (Months 4–6) Foetus grows bigger; mother feels movements 3 3rd Trimester (Months 7–9) Rapid growth; baby prepares for life outside the womb 4 Childbirth Uterine contractions push foetus through birth canal; breastfeeding provides complete nutrition and immunity
Contraception and Preventing STIs 1 Barrier Methods Condoms/vaginal covers — prevent sperm reaching egg AND reduce STI transmission 2 Oral Contraceptive Pills Alter hormones to prevent egg release; may have side effects 3 IUDs (Copper-T) Placed in uterus to prevent pregnancy STIs (gonorrhoea, herpes, syphilis, HIV/AIDS) spread through sexual contact. Some are incurable — prevention is key.
Key Takeaways: Reproduction at a Glance Asexual Reproduction Mitosis → fast, genetically identical clones; seen in bacteria, yeast, hydra, fungi, and many plants Sexual Reproduction Meiosis + fertilisation → genetic variation; essential for adaptation and evolution In Plants Pollination → fertilisation → seed & fruit formation → dispersal & germination In Humans Ovulation → fertilisation → implantation → ~9 months pregnancy → birth Sexual Health Responsible choices around contraception and STI prevention protect individuals and society