Ch 1 introduces reproduction — a fundamental biological process ensuring species continuity. It covers asexual methods (fission, budding, fragmentation, vegetative propagation) and the general features of sexual reproduction.
Single parent, offspring are clones. Binary fission (Amoeba — simple, Leishmania — longitudinal, Plasmodium — multiple). Budding (yeast, Hydra). Sporulation (Rhizopus, mosses). Vegetative propagation: runners (grass), rhizomes (ginger), tubers (potato), bulbs (onion). Advantages: faster, single parent. Disadvantage: no genetic variation.
Involves formation and fusion of gametes (syngamy). Pre-fertilisation: gametogenesis (meiosis) + gamete transfer. Fertilisation: external (aquatic) or internal (terrestrial). Post-fertilisation: zygote + embryogenesis. Life span phases: juvenile (pre-reproductive) → reproductive → senescent (post-reproductive).
Download: https://ncert.nic.in/textbook/pdf/lebo101.pdf | Complete book: https://ncert.nic.in/textbook/pdf/lebo1ps.zip
Sexual reproduction produces genetic variation through meiosis and recombination. This variation is crucial for evolution and adaptation to changing environments. Asexual reproduction produces clones — faster but genetically identical offspring that are all equally vulnerable to the same diseases or environmental changes.
Book a Trial + Diagnostic session. Get a personalized Learning Path with clear milestones, tutor match, and a plan recommendation — all within 24 hours.
Book Trial + Diagnostic →