Chapter 7 of 13

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Rajasthan (RBSE)Class 10 Science★ 5–6 marks · RBSE Class 10 Science board (Unit — Biology)

How do Organisms Reproduce?

RBSE Class 10 Science Chapter 7 — asexual reproduction (fission, budding, fragmentation, regeneration, spore formation, vegetative propagation), sexual reproduction in flowering plants (pollination, fertilisation) and humans (reproductive systems, menstruation), plus reproductive health and contraception, with board-pattern questions and full solutions.

⏱ 30 min readMedium difficulty✓ Free · NCERT-aligned

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By the end of this chapter you'll be able to…

1Explain the importance of reproduction and variation
2Describe the modes of asexual reproduction with examples
3Describe pollination and fertilisation in flowering plants
4Outline the human male and female reproductive systems and menstruation
5Discuss contraception, STDs and reproductive health

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Why this chapter matters

A diagram-heavy biology chapter that reliably yields a labelled-diagram question (flower or human reproductive system) plus short answers on asexual modes and reproductive health — a dependable 5–6 marks.

How do Organisms Reproduce? — RBSE Class 10 (Science)

No individual lives forever, yet life goes on — because organisms make copies of themselves. Reproduction is the one life process an organism can survive without, but the species cannot. This chapter looks at the many ways living things reproduce and, crucially, why variation from sexual reproduction is the raw material of evolution.

1. Why reproduce, and why variation matters

Reproduction passes on a blueprint (DNA) to the next generation. Copying is never perfect, so small variations arise. Variation lets a species survive changing conditions — if the environment shifts, some varied individuals may cope, keeping the species alive. This is why sexual reproduction, which mixes DNA from two parents, drives evolution.

2. Asexual reproduction (one parent, offspring are near-identical)

Fission — a single cell splits: binary fission (Amoeba, Leishmania — along a definite plane), multiple fission (Plasmodium → many cells at once).
Budding — a bud grows on the parent and detaches (Hydra, yeast).
Fragmentation — the body breaks into pieces, each growing into a new individual (Spirogyra).
Regeneration — a whole organism regrows from a body part (Planaria, Hydra) via specialised cells.
Spore formation — spores in a sporangium grow into new organisms (Rhizopus / bread mould).
Vegetative propagation — new plants from roots, stems or leaves (potato eyes, Bryophyllum leaf buds, layering, grafting; useful for seedless plants and for keeping desirable traits).

3. Sexual reproduction in flowering plants

The flower is the reproductive organ. Stamen (anther + filament) is the male part (makes pollen); the carpel/pistil (stigma, style, ovary) is the female part (ovary holds ovules).

Pollination — transfer of pollen from anther to stigma: self-pollination (same flower) or cross-pollination (via wind, water, insects).
Fertilisation — the pollen grain grows a pollen tube down the style to the ovule; the male gamete fuses with the egg → zygote.
After fertilisation: ovule → seed (with embryo), ovary → fruit. The seed germinates into a new plant.

4. Sexual reproduction in humans

Puberty brings sexual maturity (secondary sexual characters: body hair, voice change, breast development, etc.).

Male system: testes make sperm (and testosterone); sperm travel via the vas deferens; glands add fluid to form semen; the urethra carries it out. Testes lie in the scrotum (cooler, for sperm formation).
Female system: ovaries release an egg (one each month) and make oestrogen; the egg travels down the fallopian tube, where fertilisation may occur; the fertilised egg implants in the uterus and develops via the placenta.
Menstruation: if the egg is not fertilised, the thickened uterus lining is shed — the ~28-day menstrual cycle.

5. Reproductive health

Contraception prevents pregnancy: barrier (condoms — also prevent STDs), hormonal (pills — change hormone balance), IUCD (copper-T), surgical (vasectomy/tubectomy).
Sexual contact can spread STDs (e.g. gonorrhoea, syphilis, HIV-AIDS) — barrier methods reduce risk.
Prenatal sex determination is illegal in India (to prevent female foeticide and keep a healthy sex ratio).

6. Closing thought

Asexual reproduction is fast and faithful (identical copies); sexual reproduction is slower but generates variation — the fuel of evolution. Know the asexual types with their organisms, the flower and human reproductive structures, and the responsible-health facts. The RBSE board reliably sets a labelled-diagram question (flower or human system) plus short-answer questions worth 5–6 marks.

Key formulas & results

Everything you need to memorise, in one card. Screenshot this for revision.

Asexual modes

fission, budding, fragmentation, regeneration, spores, vegetative

One parent; near-identical offspring.

Flower parts

stamen (anther+filament) male; carpel (stigma-style-ovary) female

Reproductive organ of a plant.

Fertilisation (plant)

pollen tube → ovule; gamete fusion → zygote

Ovule→seed, ovary→fruit.

Male system

testes → vas deferens → urethra (semen)

Testes make sperm + testosterone.

Female system

ovary → fallopian tube → uterus

Fertilisation in the tube; development in the uterus.

Contraception

barrier, hormonal, IUCD, surgical

Barrier also prevents STDs.

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Common mistakes & fixes

These are the exact errors that cost students marks in board exams. Read them once, save yourself the trouble.

WATCH OUT

✗ Confusing binary and multiple fission

✓ Binary fission gives 2 cells (Amoeba); multiple fission gives many at once (Plasmodium).

WATCH OUT

✗ Saying asexual reproduction creates variation

✓ Asexual offspring are near-identical; SEXUAL reproduction creates significant variation by mixing two parents' DNA.

WATCH OUT

✗ Mixing up where fertilisation and development occur in humans

✓ Fertilisation occurs in the fallopian tube; development occurs in the uterus.

WATCH OUT

✗ Confusing pollination with fertilisation

✓ Pollination is the TRANSFER of pollen to the stigma; fertilisation is the later FUSION of gametes.

WATCH OUT

✗ Forgetting the fate of ovule and ovary

✓ After fertilisation the ovule becomes the seed and the ovary becomes the fruit.

NCERT exercises (with solutions)

Every NCERT exercise from this chapter — what it covers and how many questions to expect.

Intext questions

Asexual modes, flower, human reproduction

Questions

Ex s

Exercises

Comparisons, diagrams, reproductive health

Questions

Practice problems

Try each one yourself before tapping "Show solution". Active recall > rereading.

Q1EASY· Asexual

Name the mode of reproduction in yeast.

▶ Show solution

Step 1 — Yeast reproduces by budding.

✦ Answer: budding.

Q2EASY· Flower

Name the male and female reproductive parts of a flower.

▶ Show solution

Step 1 — Male: stamen; Female: carpel (pistil).

✦ Answer: stamen (male), carpel (female).

Q3EASY· Human

Where does fertilisation occur in the human female body?

▶ Show solution

Step 1 — In the fallopian tube (oviduct).

✦ Answer: fallopian tube.

Q4MEDIUM· Variation

Why is variation beneficial to a species though not always to the individual?

▶ Show solution

Step 1 — Variation may not help a single individual in current conditions.

Step 2 — But if conditions change, some varied individuals survive, so the species persists.

✦ Answer: variation improves the species' chances of surviving environmental change.

Q5MEDIUM· Vegetative

Give two advantages of vegetative propagation.

▶ Show solution

Step 1 — Plants that do not produce viable seeds (e.g. banana) can be grown.

Step 2 — Offspring are genetically identical, preserving desirable traits, and flower/fruit earlier.

✦ Answer: propagates seedless plants and preserves desirable traits (faster flowering).

Q6MEDIUM· Pollination

Differentiate self-pollination and cross-pollination.

▶ Show solution

Step 1 — Self-pollination: pollen transferred within the same flower/plant.

Step 2 — Cross-pollination: pollen transferred to a different plant, usually via wind, water or insects.

✦ Answer: same flower vs different plant (via agents).

Q7HARD· Fertilisation

Describe fertilisation in a flowering plant and the fate of the ovule and ovary.

▶ Show solution

Step 1 — After pollination the pollen grain grows a pollen tube down the style to an ovule.

Step 2 — The male gamete fuses with the egg to form a zygote (fertilisation).

Step 3 — The ovule develops into a seed and the ovary into a fruit.

✦ Answer: gamete fusion via pollen tube; ovule→seed, ovary→fruit.

Q8HARD· Menstruation

What is menstruation and why does it occur?

▶ Show solution

Step 1 — Each cycle the uterus lining thickens to receive a fertilised egg.

Step 2 — If the egg is not fertilised, the lining and blood are shed through the vagina.

Step 3 — This monthly shedding (~28-day cycle) is menstruation.

✦ Answer: shedding of the unused uterine lining when fertilisation does not occur.

Q9HARD· Reproductive health

Why are barrier methods of contraception considered doubly useful?

▶ Show solution

Step 1 — Barrier methods (condoms) physically prevent sperm meeting the egg, avoiding pregnancy.

Step 2 — They also prevent the transmission of sexually transmitted diseases (including HIV).

✦ Answer: they prevent both pregnancy and STDs.

Q10MEDIUM· Regeneration

How is regeneration different from reproduction?

▶ Show solution

Step 1 — Regeneration regrows lost body parts (or a whole body from a piece) using specialised cells.

Step 2 — It is not the normal mode of producing new individuals for most such organisms.

✦ Answer: regeneration restores/ regrows the body; it is not the routine reproduction of the species.

5-minute revision

The whole chapter, distilled. Read this the night before the exam.

•Reproduction passes on DNA; copying errors give variation, fuel for evolution.
•Asexual: fission, budding, fragmentation, regeneration, spores, vegetative.
•Flower: stamen (male), carpel (female); pollination then fertilisation.
•Ovule → seed; ovary → fruit after fertilisation.
•Human: sperm in testes; egg in ovary; fertilisation in fallopian tube; development in uterus.
•Menstruation sheds the uterus lining when no fertilisation occurs.
•Contraception: barrier, hormonal, IUCD, surgical; barrier also stops STDs.

Rajasthan (RBSE) marks blueprint

Where the marks come from in this chapter — so you can plan your prep.

Typical chapter weightage: 5–6 marks

Question type	Marks each	Typical count	What it tests
MCQ / very short	1	1–2	Asexual modes, flower/human parts
Short answer	2	1	Pollination, variation, vegetative propagation
Long answer / diagram	3	1	Flower/human system diagram or fertilisation

Prep strategy

Practise labelled diagrams of a flower and both human systems
Learn each asexual mode with its example organism
Distinguish pollination vs fertilisation clearly
Know contraception methods and reproductive-health facts

Where this shows up in the real world

This chapter isn't just an exam topic — it lives in the world around you.

Agriculture and horticulture

Vegetative propagation, grafting and tissue culture multiply desirable crops.

Public health

Contraception and STD prevention support family planning and health.

Medicine

Understanding menstruation and fertility underlies reproductive healthcare.

Conservation

Breeding and propagation techniques help preserve rare species.

Exam strategy

Battle-tested tips from teachers and toppers for this chapter.

Draw fully labelled diagrams for flower and human systems.
Pair each asexual mode with its example organism.
Separate pollination and fertilisation explicitly.
Give balanced, factual answers on reproductive health.
State the fate of ovule and ovary in plant-fertilisation answers.

Going beyond the textbook

For olympiad aspirants and curious learners — topics that build on this chapter.

Double fertilisation in angiosperms and endosperm formation.
Hormonal control of the menstrual cycle (FSH, LH, oestrogen, progesterone).
Alternation of generations in plants.
Genetics of sex determination (XX/XY).

Where else this chapter is tested

CBSE board isn't the only one — other exams test this chapter too.

RBSE Class 10 Board (BSER Ajmer)High — diagram and reproduction questions every year

NTSE / state scholarshipMedium — biology MCQs

NEET FoundationHigh — human reproduction is core NEET biology

Science Olympiad (NSO)Medium — reproduction and health

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Questions students ask

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Yes — RBSE (BSER, Ajmer) prescribes the NCERT Science textbook, so chapters and concepts match the national syllabus while RBSE sets its own exam pattern.

It combines DNA from two parents and reshuffles genes, so offspring differ from each other and the parents; asexual offspring are near-identical copies.

Pollination is the transfer of pollen from anther to stigma. Fertilisation is the later fusion of the male gamete with the egg inside the ovule.

To prevent female foeticide and maintain a healthy male-to-female sex ratio; it is illegal under the law.

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