Revision Notes Class 10 Science Chapter 7 – How do Organisms Reproduce?

• Why reproduce: not needed for an individual’s own survival, but essential for a species’ continuity across generations.
• Asexual modes: fission (binary – Amoeba/Leishmania; multiple – Plasmodium), budding (Yeast, Hydra), fragmentation (Spirogyra), regeneration (Planaria), spore formation (Rhizopus), vegetative propagation (roots/stems/leaves – e.g. potato eyes, Bryophyllum leaf buds).
• Sexual reproduction: needs two parents/gametes (male + female), produces genetically varied offspring – variation is the raw material for evolution/adaptation.
• Flower parts: stamen (filament + anther, male, produces pollen) and pistil/carpel (stigma + style + ovary with ovules, female). Bisexual flower = both in one flower (hibiscus); unisexual = only one (papaya, cucumber).
• Human male system: testis (sperm + testosterone) → vas deferens → seminal vesicle + prostate (add fluid, forms semen) → urethra.
• Human female system: ovary (egg + oestrogen) → fallopian tube (fertilisation site) → uterus (implantation/gestation) → vagina.
• Menstrual cycle: ~28 days; uterine lining thickens to prepare for a fertilised egg; if fertilisation doesn’t occur, lining sheds as menstruation.
• Contraception: barrier (condom, diaphragm), hormonal (pills – prevent ovulation), IUD/copper-T (prevents implantation), surgical (vasectomy/tubectomy – permanent).

Part of the Class 10 Science Chapter 7 cluster: Solutions | Extra Questions (HOTS) | Revision Notes | Formulas Handbook | Class 10 Science book page. These Class 10 Science Chapter 7 notes are ideal for quick revision just before exams.

Last Updated: October 24, 2026

Common Mistakes Students Make in This Chapter

Why This Chapter Matters

How do Organisms Reproduce? is one of the standard chapters in the CBSE/NCERT Class 10 Science syllabus and questions from it appear regularly in board exams, in formats ranging from 1-mark objective questions to longer 3-5 mark descriptive or numerical questions. Because the concepts here often build on earlier chapters (and feed into later ones), a solid grip on this chapter also makes the rest of the Science syllabus easier to follow.

How to Use These Notes

These revision notes are meant for quick recall in the last few days before an exam or unit test — they are not a substitute for first reading the full chapter and working through examples in the NCERT textbook. A good routine is: read the chapter once, solve the in-text and end-of-chapter questions using the linked Solutions, then come back to this page a day or two before the exam to refresh the key definitions and formulas without re-reading the whole chapter.

Quick visual: a worked diagram from the full Solutions page, for reference.

Frequently Asked Questions

What is the difference between external and internal fertilization?
External fertilization occurs outside the body (common in aquatic animals like fish, where eggs and sperm meet in water); internal fertilization occurs inside the female’s body (common in land animals like humans), offering the developing embryo more protection.

Why is DNA copying important during reproduction?
Accurate DNA copying ensures that offspring inherit the genetic information needed to develop similar features to their parents; small variations that occur during copying are also the raw material for evolution, since useful variations can help a species survive changing conditions.

What to Revise First (and Last) in This Chapter

Written by Satish

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