CBSE Class 10 Science: Reproduction — Complete Notes 2026

Modes of Reproduction

• Asexual: single parent; offspring genetically identical (clone); examples: fission, budding, fragmentation, spore formation, vegetative propagation
• Sexual: two parents; involves gametes (male + female); leads to genetic variation in offspring
• Importance of sexual reproduction: variation allows natural selection and adaptation to changing environments

Asexual Reproduction in Detail

• Binary fission (Amoeba): nucleus divides first (karyokinesis), then cytoplasm (cytokinesis)
• Budding (Hydra, Yeast): small bud grows, detaches, becomes new organism
• Fragmentation (Spirogyra): body breaks into pieces, each regenerates; regeneration (Planaria): each fragment grows into complete organism

Reproduction in Plants

• Vegetative: stolons (grass), tubers (potato), bulbs (onion), rhizomes (ginger)
• Artificial methods: cutting (rose), layering (jasmine), grafting (mango); tissue culture (virus-free plants)
• Flower parts: sepals, petals, stamens (male — anther + filament), carpel (female — stigma + style + ovary)

Pollination and Fertilisation in Plants

• Self-pollination: pollen from same flower; cross-pollination: from another flower (insects, wind, water)
• Double fertilisation in angiosperms: one sperm fuses with egg → zygote; other fuses with polar nuclei → endosperm
• Seed dispersal: wind (dandelion), water (coconut), animal (hooks, fruits), explosive (Impatiens)

Human Reproductive System

• Male: testes (sperm production, testosterone), vas deferens, seminal vesicles, prostate, urethra
• Female: ovaries (egg, oestrogen, progesterone), fallopian tubes, uterus, cervix, vagina
• Sperm structure: head (nucleus + acrosome), middle piece (mitochondria for energy), tail (flagellum for motility)

Menstrual Cycle and Pregnancy

• 28-day cycle: menstruation (days 1–5), follicular phase (5–14), ovulation (day 14), luteal phase (14–28)
• Fertilisation: in fallopian tube; zygote travels to uterus; implantation on day 6–7
• Placenta: connects foetus to uterus; exchanges nutrients/waste; produces HCG hormone

Reproductive Health

• Contraception: barrier (condom), hormonal (pills), IUDs, surgical (sterilisation)
• STIs: gonorrhoea, syphilis (bacterial — curable); HIV/AIDS, herpes (viral — manageable, not curable)
• CBSE exam note: contraception types and their mechanisms are frequently tested