Chapter 7: How Do Organisms Reproduce
Simple, exam-focused CBSE Class 10 Science notes — star topics, concepts, common mistakes, and previous year question patterns, all on one page.
Chapter 7: How Do Organisms Reproduce
⭐ Star Topics / Most Important
- Modes of asexual reproduction
- Human male and female reproductive systems
- Menstrual cycle
- Contraceptive methods and STIs
Detailed Chapter Notes
Asexual reproduction: fission (amoeba), budding (Hydra), fragmentation (Spirogyra), regeneration (Planaria), spore formation (Rhizopus), and vegetative propagation (cutting, grafting, layering).
Male reproductive system: testes (produce sperm and testosterone), epididymis (maturation/storage), vas deferens (delivery). Female: ovaries (eggs and oestrogen), fallopian tubes (site of fertilisation), uterus (implantation and development).
The menstrual cycle (~28 days) thickens the uterus lining for possible pregnancy; if the egg isn't fertilised, the lining sheds as menstrual bleeding.
Fertilisation: sperm fuses with egg in the fallopian tube → zygote → implants in uterus → embryo → foetus over ~9 months, connected to the uterine wall via the placenta.
Contraception: barrier (condoms — the only method that also prevents STIs), hormonal (pills), IUDs (copper-T), surgical (tubectomy/vasectomy). STIs like HIV-AIDS, gonorrhoea, syphilis spread through unprotected contact.
Reproduction is essential for survival of the SPECIES, not the individual — a very commonly written wrong line. Also, questions on "why is variation useful for a species" expect the answer linked to survival during environmental changes, not just "different traits are good."
Search on YouTube: How Do Organisms Reproduce Class 10 one shot for a visual walkthrough of this chapter.
- Why is variation beneficial to the species but not necessarily for an individual? (3 marks, HOTS)
- Draw a labelled diagram of the human female reproductive system (3 marks)
- What are the different methods of contraception? (3 marks)
- Explain the process of fertilisation in human beings (2 marks)
- Why do organisms reproduce? (2 marks)