Reproduction in Plants and Animals
Class 9 Science Foundation Module • Asexual Reproduction • Sexual Reproduction • Human Reproductive Health
Chapter Overview
What You Will Learn
You will learn how organisms produce new individuals through asexual and sexual reproduction, how flowers form seeds, and how humans reproduce through specialised organs and gametes.
Why It Matters
Reproduction maintains continuity of life, introduces variations, supports evolution and explains important biological processes such as pollination, fertilisation, pregnancy and reproductive health.
Exam Relevance
This chapter is important for definitions, diagrams, flowcharts, comparison tables, application-based questions and case-study questions in CBSE-style exams.
Full Chapter Introduction
Reproduction is the biological process by which living organisms produce new individuals of their own kind. Every organism has a limited life span, so reproduction ensures that life continues from one generation to the next.
Reproduction is not essential for the survival of one individual organism, but it is essential for the survival of a species. Without reproduction, a species would disappear after all existing members die.
Remember This
Nutrition, respiration and excretion keep an individual alive. Reproduction keeps the species alive.
Why does reproduction create variation?
In sexual reproduction, genetic material from two parents combines. This produces offspring with a new combination of characters, which causes variation.
Types of Reproduction
Asexual Reproduction
Only one parent is involved. Gametes are not formed. Offspring are usually genetically identical to the parent and are called clones.
- Fast process
- Common in unicellular organisms and some plants
- Examples: Amoeba, yeast, Hydra, bacteria, fungi, potato, ginger
Sexual Reproduction
Usually two parents are involved. Male and female gametes fuse to form a zygote. Offspring show variation.
- Slower than asexual reproduction
- Involves gamete formation and fertilisation
- Examples: flowering plants, humans, animals
| Basis | Asexual Reproduction | Sexual Reproduction |
|---|---|---|
| Parents involved | One | Usually two |
| Gametes | Not formed | Male and female gametes are formed |
| Fertilisation | Absent | Present |
| Variation | Very little | High |
| Speed | Fast | Comparatively slow |
| Examples | Amoeba, yeast, Hydra, potato | Humans, frogs, flowering plants |
Board Exam Focus
Questions often ask: “Differentiate between asexual and sexual reproduction” or “Why is sexual reproduction better for evolution?”
Asexual Reproduction in Detail
In asexual reproduction, new organisms are produced from a single parent without formation and fusion of gametes. It is common in bacteria, protozoa, fungi, algae and some plants.
5.1 Binary Fission
Binary fission is a type of asexual reproduction in which one parent cell divides into two daughter cells. Each daughter cell grows into a complete organism.
| Type of Binary Fission | Plane of Division | Example |
|---|---|---|
| Irregular binary fission | Division can occur in any plane | Amoeba |
| Longitudinal binary fission | Along the length of body | Euglena |
| Transverse binary fission | Across the width of body | Paramecium |
Diagram Placeholder: Binary Fission in Amoeba
Label: Parent Amoeba → Nuclear division → Cytoplasmic division → Two daughter Amoebae
5.2 Multiple Fission
In multiple fission, the nucleus of the parent cell divides repeatedly to form many daughter nuclei. Later, the cytoplasm divides and many daughter cells are formed at the same time.
Example: Plasmodium, the protozoan that causes malaria, reproduces by multiple fission.
Why does Plasmodium use multiple fission?
Multiple fission helps Plasmodium produce many daughter cells quickly inside the host body, increasing its chances of survival and spread.
5.3 Budding
In budding, a small outgrowth called a bud develops on the parent body. The bud grows, separates from the parent and forms a new organism.
Examples: Yeast and Hydra.
5.4 Fragmentation
In fragmentation, the body of an organism breaks into two or more fragments, and each fragment grows into a new organism.
Example: Spirogyra, a filamentous green alga.
Common Mistake
Do not write “fragmentation occurs in Amoeba.” Amoeba reproduces by binary fission. Fragmentation occurs in filamentous organisms like Spirogyra.
5.5 Regeneration
Regeneration is the ability of an organism to regrow lost body parts. In some simple organisms, if the body is cut into pieces, each piece can develop into a complete organism.
Examples: Planaria and Hydra.
Important Difference
Regeneration is not the same as reproduction in all organisms. A lizard can regenerate its tail, but the tail does not grow into a new lizard.
5.6 Spore Formation
In spore formation, tiny reproductive bodies called spores are produced inside spore cases. Spores have a protective covering and can survive unfavourable conditions.
Examples: Rhizopus, Mucor, ferns and mosses.
Diagram Placeholder: Spore Formation in Rhizopus
Label: Sporangium contains spores. When mature, it bursts and releases spores.
5.7 Vegetative Propagation in Plants
Vegetative propagation is an asexual method in which new plants develop from vegetative parts such as roots, stems, leaves or buds.
| Plant Part | Example | How New Plant Forms |
|---|---|---|
| Stem tuber | Potato | Eyes of potato develop into new shoots |
| Rhizome | Ginger | Underground stem grows into new plant |
| Bulb | Onion, garlic | Bud grows into new plant |
| Leaf | Bryophyllum | Buds on leaf margins form new plants |
| Root | Sweet potato, Dahlia | Adventitious buds produce new shoots |
Advantages of Vegetative Propagation
- Produces plants quickly.
- Produces genetically identical plants with desired features.
- Useful for plants that do not produce viable seeds.
- Used in agriculture and horticulture for banana, sugarcane, rose, potato and grapes.
Sexual Reproduction in Flowering Plants
A flower is the reproductive organ of a flowering plant. It contains male and female reproductive parts. Sexual reproduction in plants involves formation of gametes, pollination, fertilisation, embryo formation, seed formation and fruit formation.
6.1 Parts of a Flower
Male Reproductive Part: Stamen
The stamen consists of two parts:
- Anther: produces pollen grains.
- Filament: supports the anther.
Pollen grains contain the male gametes.
Female Reproductive Part: Pistil/Carpel
The pistil consists of three parts:
- Stigma: receives pollen grains.
- Style: tube-like passage connecting stigma to ovary.
- Ovary: contains ovules.
Ovule contains the female gamete or egg cell.
Labelled Diagram Placeholder: Structure of a Flower
Ovules
6.2 Pollination
Pollination is the transfer of pollen grains from the anther to the stigma of a flower.
| Type | Meaning | Result |
|---|---|---|
| Self-pollination | Pollen is transferred to the stigma of the same flower or another flower on the same plant. | Less variation |
| Cross-pollination | Pollen is transferred to the stigma of a flower on another plant of the same species. | More variation |
Why are petals colourful and fragrant?
Colourful petals, fragrance and nectar attract insects and birds. These animals help transfer pollen from one flower to another.
6.3 Agents of Pollination
Wind
Maize, grasses
Water
Vallisneria
Insects
Bee, butterfly
Birds
Sunbird, hummingbird
6.4 Fertilisation in Plants
After pollination, the pollen grain germinates on the stigma and forms a pollen tube. The pollen tube grows through the style and reaches the ovule inside the ovary. Male gametes travel through the pollen tube. One male gamete fuses with the egg cell to form a zygote.
6.5 After Fertilisation
| Structure Before Fertilisation | Structure After Fertilisation |
|---|---|
| Ovule | Seed |
| Ovary | Fruit |
| Zygote | Embryo |
| Ovary wall | Fruit wall/pericarp |
Double Fertilisation and Triple Fusion in Plants
Flowering plants show a special type of fertilisation called double fertilisation. Two male gametes enter the embryo sac. One fuses with the egg cell and the other fuses with two polar nuclei.
First Fusion
One male gamete fuses with the egg cell.
Second Fusion / Triple Fusion
The second male gamete fuses with two polar nuclei. Since three nuclei are involved, it is called triple fusion.
Remember This
Double fertilisation means two fusion events. Triple fusion means fusion of one male gamete with two polar nuclei.
Why is endosperm important?
Endosperm stores food and nourishes the developing embryo inside the seed.
Sexual Reproduction in Human Beings
Human beings reproduce sexually. Male and female reproductive systems produce gametes. The male gamete is called sperm and the female gamete is called ovum or egg. Fertilisation forms a zygote, which develops into an embryo and later a foetus.
Board Exam Focus
Human reproduction questions usually test functions of organs, fertilisation site, menstrual cycle, placenta, reproductive health and contraception.
Male Reproductive System
The male reproductive system produces, stores and transports sperms. It also secretes hormones and fluids that help sperms survive and move.
| Organ | Function |
|---|---|
| Testes | Produce sperms and male sex hormone testosterone. |
| Scrotum | Holds testes outside the abdominal cavity and keeps them slightly cooler for sperm formation. |
| Vas deferens / sperm duct | Transports sperms from testes towards urethra. |
| Seminal vesicles and prostate gland | Add fluid to sperms to form semen and provide nourishment. |
| Urethra | Common passage for urine and semen, but not at the same time. |
| Penis | Transfers semen into the female reproductive tract. |
Diagram Placeholder: Male Reproductive System
Use this placeholder to insert a labelled diagram in Canva or WordPress image block.
Remember This
Testes have two major functions: sperm formation and testosterone secretion.
Female Reproductive System
The female reproductive system produces ova, receives sperms, provides the site for fertilisation and supports development of the embryo into a foetus.
| Organ | Function |
|---|---|
| Ovaries | Produce ova and female sex hormones estrogen and progesterone. |
| Oviduct / Fallopian tube | Transports ovum from ovary to uterus. Fertilisation usually occurs here. |
| Uterus | Muscular organ where embryo implants and develops. |
| Cervix | Narrow lower part of uterus opening into vagina. |
| Vagina | Receives sperms and acts as birth canal during childbirth. |
Ovulation
Ovulation is the release of a mature ovum from the ovary. In humans, usually one ovum is released during a menstrual cycle.
Menstruation
If fertilisation does not occur, the thickened lining of the uterus breaks down and comes out through the vagina along with blood. This process is called menstruation.
Menopause
Menopause is the natural stage in a woman’s life when menstrual cycles stop permanently and ovulation no longer occurs regularly.
Common Mistake
Do not write that fertilisation occurs in the uterus. Fertilisation usually occurs in the oviduct or fallopian tube.
Fertilisation, Pregnancy and Development
11.1 Fertilisation
Fertilisation is the fusion of male and female gametes. In humans, sperm fuses with ovum in the fallopian tube to form a zygote.
11.2 Zygote to Embryo
The zygote divides repeatedly by mitosis and forms a ball of cells. It moves towards the uterus and gets attached to the uterine wall. This process is called implantation. After implantation, the developing structure is called an embryo.
11.3 Embryo to Foetus
As the embryo grows, organs begin to develop. When the body parts become recognisable, the developing baby is called a foetus.
11.4 Placenta
The placenta is a special tissue that connects the developing foetus with the mother’s body. It helps in exchange of nutrients, oxygen and waste materials.
| Material | Direction |
|---|---|
| Oxygen and nutrients | Mother to foetus |
| Carbon dioxide and waste | Foetus to mother |
Remember This
The blood of the mother and foetus does not directly mix. Exchange occurs through the placenta.
11.5 Gestation
The period from fertilisation to birth is called gestation. In humans, it is approximately nine months.
Reproductive Health, STDs and Birth Control
Reproductive health means complete physical, mental and social well-being in all matters related to the reproductive system. It includes hygiene, awareness, prevention of infections and responsible reproductive choices.
Sexually Transmitted Diseases
Sexually transmitted diseases, or STDs, are infections that can spread through sexual contact. Examples include HIV/AIDS, syphilis, gonorrhoea and hepatitis B.
Health Note
Students should learn this topic scientifically and respectfully. Reproductive health education helps prevent disease, misinformation and unsafe practices.
How to Avoid STDs
- Maintain reproductive hygiene.
- Avoid unsafe sexual contact.
- Use medically recommended protective methods.
- Seek medical advice for symptoms or concerns.
- Avoid sharing needles or sharp instruments.
Avoiding Unwanted Pregnancy
| Method | Meaning | Example |
|---|---|---|
| Barrier method | Prevents sperm from reaching ovum | Condom |
| Hormonal method | Prevents ovulation or implantation under medical guidance | Oral contraceptive pills |
| Intrauterine device | Device placed in uterus by a medical professional | Copper-T |
| Surgical method | Permanent method to prevent gamete transport | Vasectomy, tubectomy |
Board Exam Focus
Contraception questions should be answered scientifically. Mention that contraceptive methods help avoid unwanted pregnancy and some barrier methods also reduce STD risk.
Important Scientific Terms
Concept Maps and Flowcharts
Asexual Reproduction Map
Sexual Reproduction in Plants
Human Reproduction
Important Equations and Transformations
This chapter does not contain numerical formulae, but these biological transformations are very important for exam answers.
NCERT Focus Section
Important NCERT Line
Reproduction is necessary for the continuation of species.
Important NCERT Line
Sexual reproduction produces variation because offspring receive genetic material from two parents.
Important NCERT Line
Pollination is followed by fertilisation in flowering plants.
Important NCERT Line
The placenta helps in exchange of materials between mother and foetus.
Board Exam Focus and Competitive Edge
Most Important CBSE Points
- Difference between sexual and asexual reproduction.
- Types of asexual reproduction with examples.
- Structure of flower and functions of parts.
- Pollination vs fertilisation.
- Ovule becomes seed and ovary becomes fruit.
- Functions of male and female reproductive organs.
- Placenta and menstrual cycle.
- Reproductive health and contraception.
Foundation/Olympiad Edge
- Sexual reproduction introduces variation, which supports natural selection.
- Double fertilisation is unique to flowering plants.
- Endosperm nourishes the embryo.
- External fertilisation produces many gametes because survival chances are lower.
- Internal fertilisation protects the developing embryo better.
Common Misconceptions and Mistakes
Mistake 1
Writing that pollination and fertilisation are the same. Pollination is pollen transfer; fertilisation is gamete fusion.
Mistake 2
Writing that fertilisation in humans occurs in the uterus. It usually occurs in the fallopian tube.
Mistake 3
Confusing embryo and foetus. Foetus is a later stage where body parts are recognisable.
Mistake 4
Writing that all asexual reproduction is binary fission. Asexual reproduction has many types.
Mistake 5
Writing that placenta produces the baby. Placenta supports exchange of materials; the foetus develops in the uterus.
Mistake 6
Forgetting examples. Every type of asexual reproduction should be written with one correct example.
Practice Questions
A. MCQs
- The male gamete in humans is called:
A. Ovum B. Sperm C. Zygote D. Embryo - Binary fission occurs in:
A. Amoeba B. Rose C. Human D. Mango - The part of flower that produces pollen grains is:
A. Stigma B. Style C. Anther D. Ovary - Fertilisation in humans usually occurs in:
A. Uterus B. Vagina C. Fallopian tube D. Ovary - Ovule after fertilisation becomes:
A. Fruit B. Seed C. Pollen D. Sepal - Spore formation occurs in:
A. Rhizopus B. Dog C. Human D. Hen - The tissue that connects foetus with mother is:
A. Ovary B. Placenta C. Testis D. Stigma - Triple fusion forms:
A. Zygote B. Embryo C. Endosperm D. Pollen - Vegetative propagation by leaves occurs in:
A. Potato B. Ginger C. Bryophyllum D. Onion - Menstruation occurs when:
A. Fertilisation occurs B. Uterine lining breaks down C. Placenta forms D. Pollen tube forms
B. Fill in the Blanks
- The fusion of male and female gametes is called __________.
- The female reproductive part of a flower is called __________.
- The zygote develops into an __________.
- The ovary of a flower develops into a __________.
- The release of ovum from ovary is called __________.
C. True or False
- Asexual reproduction involves only one parent.
- Pollination and fertilisation are the same process.
- Testes produce sperms.
- Placenta helps in exchange of materials between mother and foetus.
- Vegetative propagation always produces highly different offspring.
D. Assertion-Reason Questions
-
Assertion: Sexual reproduction produces variation.
Reason: In sexual reproduction, genetic material from two parents combines. -
Assertion: Pollination must occur before fertilisation in flowering plants.
Reason: Pollination brings pollen grains to stigma, from where male gametes can reach the ovule. -
Assertion: The scrotum keeps testes outside the abdominal cavity.
Reason: Sperm formation requires a temperature slightly lower than normal body temperature.
E. Very Short Answer Questions
- Define reproduction.
- Name the male and female gametes in humans.
- What is pollination?
- Name the site of fertilisation in humans.
- What is vegetative propagation?
F. Short Answer Questions
- Differentiate between pollination and fertilisation.
- Explain binary fission with example.
- Write the functions of testes and ovaries.
- What is placenta? Write its function.
- Why is sexual reproduction important for evolution?
G. Long Answer Questions
- Explain sexual reproduction in flowering plants with a labelled diagram.
- Describe the male reproductive system in humans with functions of its parts.
- Describe the female reproductive system in humans with functions of its parts.
- Explain the journey from fertilisation to birth in humans.
- Explain different types of asexual reproduction with examples.
H. Case Study Question
A student observed that a potato kept in a moist place developed small green shoots from its eyes. Another student observed that Rhizopus growing on bread produced black round structures on thread-like hyphae. Both students concluded that organisms can reproduce without seeds or gamete fusion.
- Name the type of reproduction shown by potato.
- What are the black round structures in Rhizopus called?
- Why are these methods called asexual reproduction?
- Give one advantage of vegetative propagation.
Answer Key
MCQs
1-B, 2-A, 3-C, 4-C, 5-B, 6-A, 7-B, 8-C, 9-C, 10-B
Fill in the Blanks
1. Fertilisation, 2. Pistil/Carpel, 3. Embryo, 4. Fruit, 5. Ovulation
True/False
1. True, 2. False, 3. True, 4. True, 5. False
Assertion-Reason
1. Both A and R are true, and R explains A. 2. Both A and R are true, and R explains A. 3. Both A and R are true, and R explains A.
Case Study
1. Vegetative propagation. 2. Sporangia. 3. Because only one parent is involved and gamete fusion does not occur. 4. It produces new plants quickly and preserves desired characters.
One-Page Final Revision Sheet
Must Remember
- Reproduction maintains continuity of species.
- Asexual reproduction involves one parent and produces clones.
- Sexual reproduction involves gametes and produces variation.
- Binary fission: Amoeba, Euglena, Paramecium.
- Multiple fission: Plasmodium.
- Budding: Yeast and Hydra.
- Fragmentation: Spirogyra.
- Regeneration: Planaria.
- Spore formation: Rhizopus.
- Vegetative propagation: potato, ginger, onion, Bryophyllum.
- Anther produces pollen grains.
- Stigma receives pollen grains.
- Ovary contains ovules.
- Pollination is pollen transfer.
- Fertilisation is gamete fusion.
- Ovule becomes seed; ovary becomes fruit.
- Triple fusion forms endosperm.
- Testes produce sperms and testosterone.
- Ovaries produce ova and hormones.
- Fertilisation in humans usually occurs in fallopian tube.
- Placenta helps exchange oxygen, nutrients and wastes.
- Menstruation occurs when fertilisation does not happen.
- Contraception helps prevent unwanted pregnancy.
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