Ch 9 covers how animals reproduce. Students learn about sexual reproduction (fertilisation, embryo development) and asexual reproduction (budding, binary fission). Key concepts include viviparous vs oviparous animals and metamorphosis.
Male gamete = sperm, female gamete = ovum (egg). Fertilisation: sperm fuses with ovum to form a zygote. Internal fertilisation: inside the female body (humans, cows, dogs). External fertilisation: outside the body in water (fish, frogs). Zygote → embryo → develops organs → baby/hatchling.
Viviparous: embryo develops inside mother, gives birth to young (humans, cats). Oviparous: lay eggs, embryo develops outside (birds, reptiles, fish). Metamorphosis: dramatic change in form during development (frog: egg → tadpole → adult frog; butterfly: egg → larva → pupa → adult).
Budding: new organism grows as a bud on parent (Hydra). Binary fission: parent splits into two (Amoeba). Does not require two parents; offspring are genetically identical to parent.
Download: https://ncert.nic.in/textbook/pdf/hesc109.pdf | Complete book: https://ncert.nic.in/textbook/pdf/hesc1ps.zip
IVF (In Vitro Fertilisation) is a technique where fertilisation occurs outside the body in a laboratory. The egg and sperm are combined in a dish, and the resulting embryo is placed into the mother's uterus. Babies born through IVF are sometimes called "test-tube babies".
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