Class 10th Science Chapter 7 – How Do Organisms Reproduce? | Important Diagrams and Labelling

How Do Organisms Reproduce? | Important Diagrams and Labelling

Class 10 Science | Chapter 8 | CBSE + Foundation + Competitive

Important Diagrams • Labelling • Concept Revision • MCQs • Board Questions

How Do Organisms Reproduce? | Important Diagrams and Labelling

1. Chapter 8 – Important Diagrams

English: Diagrams are very important in Class 10 Science Chapter 8. Questions may ask students to draw, identify, label or explain structures related to reproduction.

हिन्दी: कक्षा 10 विज्ञान अध्याय 8 में diagrams बहुत महत्वपूर्ण हैं। परीक्षा में diagram बनाना, parts को label करना, structure पहचानना या उसके functions बताना पूछा जा सकता है।

Important Diagrams Covered:
Asexual Reproduction Binary Fission Budding Vegetative Propagation Flower Male Reproductive System Female Reproductive System Sperm Ovum Menstrual Cycle Fertilisation Implantation

2. Structure of a Flower – Important Labelling

A flower is the reproductive structure of a flowering plant. The four main whorls are:

• Sepals
• Petals
• Stamen – male reproductive part
• Pistil/Carpel – female reproductive part

🌸 Flower – Important Labels

Must Remember: Stamen = Filament + Anther
Pistil/Carpel = Stigma + Style + Ovary
Ovary contains Ovules.

3. Pollination and Fertilisation in Flower

Pollination: Transfer of pollen grains from anther to stigma.

Fertilisation: Fusion of male gamete with female gamete to form a zygote.

🌸 Pollination → Pollen Tube → Fertilisation

4. Male Reproductive System – Important Labelling

Important Parts: Testes, scrotum, epididymis, vas deferens, seminal vesicles, prostate gland, urethra and penis.

Testes: Produce sperm and testosterone.
Scrotum: Maintains a temperature slightly lower than body temperature, suitable for sperm formation.

♂ Male Reproductive System – Schematic Labelling

Sperm Pathway: Testis → Epididymis → Vas deferens → Urethra → Penis

5. Structure of Human Sperm – Labelling

Sperm Structure:

• Head: Contains nucleus and acrosome.
• Middle piece: Contains many mitochondria to provide energy.
• Tail: Helps in movement.

6. Female Reproductive System – Important Labelling

Important Parts: Ovaries, fallopian tubes, uterus, cervix and vagina.

Ovaries produce ova and female reproductive hormones. The uterus is the organ where implantation and development of the embryo occur.

♀ Female Reproductive System – Schematic Labelling

Important: Fertilisation in humans usually occurs in the fallopian tube. Implantation occurs in the uterine lining.

7. Structure of Ovum – Important Labelling

8. Asexual Reproduction – Important Diagrams

Asexual reproduction: A type of reproduction generally involving one parent and no fusion of gametes. Important examples:

• Binary fission – Amoeba
• Multiple fission – Plasmodium
• Budding – Hydra / Yeast
• Fragmentation – Spirogyra
• Regeneration – Planaria
• Vegetative propagation – Plants
• Spore formation – Rhizopus

Binary Fission in Amoeba

Budding in Hydra

9. Vegetative Propagation – Important Diagram

10. Menstrual Cycle – Important Diagram

A typical textbook menstrual cycle is often represented as about 28 days, but actual cycle length and ovulation timing can vary among individuals. Main phases:

• Follicular phase
• Ovulation
• Luteal phase
• Menstruation

🔄 Menstrual Cycle – Flow Diagram

11. Fertilisation and Implantation

Sperm + Ovum → Zygote → Embryo → Implantation

Sperm (23) + Ovum (23) → Zygote (46) → Embryo → Implantation

12. Most Important Labels – Quick Table

Diagram	Important Labels
Flower	Sepal, Petal, Anther, Filament, Stigma, Style, Ovary, Ovule
Male Reproductive System	Testis, Scrotum, Epididymis, Vas deferens, Seminal vesicle, Prostate, Urethra, Penis
Female Reproductive System	Ovary, Fallopian tube, Uterus, Endometrium, Cervix, Vagina
Sperm	Head, Nucleus, Acrosome, Middle piece, Mitochondria, Tail
Ovum	Cell membrane, Cytoplasm, Nucleus
Menstrual Cycle	Menstruation, Follicular phase, Ovulation, Luteal phase
Fertilisation	Sperm, Ovum, Zygote, Embryo, Implantation
Asexual Reproduction	Parent cell, Nucleus, Bud, Fragment, Daughter cells

13. Important Diagram-Based Questions

Q1. Identify the male reproductive organ that produces sperm.

Answer: Testes.

Q2. Which part of the female reproductive system receives the embryo during implantation?

Answer: Uterus.

Q3. Which part of the flower produces pollen grains?

Answer: Anther.

Q4. Name the part of the flower that receives pollen grains.

Answer: Stigma.

Q5. Where does fertilisation usually occur in humans?

Answer: Fallopian tube.

Q6. Where does implantation occur?

Answer: Uterine lining / endometrium.

Q7. Which structure of sperm helps in movement?

Answer: Tail.

Q8. Which structure of sperm contains the nucleus?

Answer: Head.

Q9. Name the reproductive structure containing ovules.

Answer: Ovary of the flower.

Q10. Which organ produces ova?

Answer: Ovary.

14. 30 MCQs – Important Diagrams & Labelling

Q1. The male reproductive organ that produces sperm is:

A) Testis

B) Prostate

C) Urethra

D) Seminal vesicle

Answer: A

Q2. The female reproductive organ that produces ova is:

A) Uterus

B) Ovary

C) Cervix

D) Vagina

Answer: B

Q3. Pollen grains are produced in:

A) Stigma

B) Style

C) Anther

D) Ovary

Answer: C

Q4. The receptive surface for pollen grains is:

A) Stigma

B) Ovule

C) Anther

D) Filament

Answer: A

Q5. The ovary of a flower contains:

A) Pollen grains

B) Ovules

C) Sperm

D) Sepals

Answer: B

Q6. Fertilisation in humans usually occurs in:

A) Uterus

B) Vagina

C) Fallopian tube

D) Ovary

Answer: C

Q7. Implantation normally occurs in:

A) Ovary

B) Uterine lining

C) Vagina

D) Fallopian tube

Answer: B

Q8. Which part of sperm provides movement?

A) Head

B) Nucleus

C) Middle piece

D) Tail

Answer: D

Q9. The middle piece of sperm contains many:

A) Mitochondria

B) Ribosomes only

C) Chloroplasts

D) Vacuoles

Answer: A

Q10. The head of sperm contains:

A) Chloroplast

B) Nucleus

C) Large vacuole

D) Ovule

Answer: B

Q11. Which is the female reproductive organ where the embryo develops?

A) Uterus

B) Ovary

C) Cervix

D) Vagina

Answer: A

Q12. The scrotum helps:

A) Produce ova

B) Maintain suitable temperature for sperm formation

C) Produce urine

D) Store bile

Answer: B

Q13. Which is the male gamete?

A) Ovum

B) Zygote

C) Sperm

D) Embryo

Answer: C

Q14. Which is the female gamete?

A) Ovum

B) Sperm

C) Embryo

D) Zygote

Answer: A

Q15. The zygote is formed by:

A) Budding

B) Fragmentation

C) Fusion of gametes

D) Binary fission

Answer: C

Q16. In a flower, stamen is the:

A) Female reproductive part

B) Male reproductive part

C) Protective part only

D) Seed

Answer: B

Q17. Pistil is generally composed of:

A) Stigma, style and ovary

B) Anther and filament

C) Sepal and petal

D) Ovule and pollen only

Answer: A

Q18. Pollination is:

A) Fusion of gametes

B) Transfer of pollen to stigma

C) Formation of zygote

D) Implantation

Answer: B

Q19. Which structure connects ovary with uterus?

A) Fallopian tube

B) Cervix

C) Vagina

D) Urethra

Answer: A

Q20. Menstruation is associated with shedding of:

A) Uterine lining

B) Ovary

C) Fallopian tube

D) Cervix

Answer: A

Q21. Ovulation means:

A) Fusion of sperm and ovum

B) Release of an ovum from an ovary

C) Implantation

D) Formation of sperm

Answer: B

Q22. The hormone surge that triggers ovulation is mainly:

A) LH

B) Insulin

C) Thyroxine

D) Adrenaline

Answer: A

Q23. Which structure transports sperm from epididymis?

A) Vas deferens

B) Ureter

C) Fallopian tube

D) Oviduct

Answer: A

Q24. Binary fission can be observed in:

A) Amoeba

B) Hydra

C) Rose

D) Human

Answer: A

Q25. Budding is commonly seen in:

A) Hydra

B) Amoeba only

C) Humans

D) Mango

Answer: A

Q26. Fragmentation is commonly associated with:

A) Spirogyra

B) Human

C) Hydra

D) Cow

Answer: A

Q27. Regeneration is well illustrated by:

A) Planaria

B) Human

C) Mango

D) Rose only

Answer: A

Q28. The male reproductive hormone produced by testes is:

A) Testosterone

B) Estrogen only

C) Insulin

D) Thyroxine

Answer: A

Q29. A human gamete normally contains:

A) 46 chromosomes

B) 23 chromosomes

C) 92 chromosomes

D) 44 chromosomes

Answer: B

Q30. A normal human zygote generally contains:

A) 23 chromosomes

B) 22 chromosomes

C) 46 chromosomes

D) 92 chromosomes

Answer: C

15. 30 Subjective Questions with Answers

2 Marks Q1. Name the four main parts of a flower.

Sepals, petals, stamens and pistil/carpel.

2 Marks Q2. Name the three parts of pistil.

Stigma, style and ovary.

2 Marks Q3. Name the two main parts of stamen.

Filament and anther.

2 Marks Q4. Name the male and female gametes in humans.

Male gamete – sperm; Female gamete – ovum.

2 Marks Q5. Name the site of fertilisation and implantation in humans.

Fertilisation usually occurs in the fallopian tube; implantation occurs in the uterine lining.

3 Marks Q6. Write three labels of the male reproductive system.

Testes, vas deferens and urethra.

3 Marks Q7. Write three labels of the female reproductive system.

Ovary, fallopian tube and uterus.

3 Marks Q8. Explain the functions of head, middle piece and tail of sperm.

Head contains nucleus, middle piece contains mitochondria for energy, and tail helps in movement.

3 Marks Q9. What is pollination? Name its two types.

Pollination is transfer of pollen from anther to stigma. It may be self-pollination or cross-pollination.

3 Marks Q10. Differentiate between pollination and fertilisation.

Pollination is transfer of pollen grains to stigma, whereas fertilisation is fusion of male and female gametes.

4 Marks Q11. Explain the structure of a flower with a labelled diagram.

A flower has sepals, petals, stamens and pistil/carpel. Stamen consists of filament and anther. Pistil consists of stigma, style and ovary. Ovary contains ovules.

4 Marks Q12. Explain the main parts of the male reproductive system.

Testes produce sperm and testosterone. Epididymis is involved in sperm maturation and storage. Vas deferens transports sperm. Accessory glands add secretions. Urethra carries semen during ejaculation.

4 Marks Q13. Explain the main parts of the female reproductive system.

Ovaries produce ova and hormones. Fallopian tubes transport the ovum and are the usual site of fertilisation. Uterus supports implantation and embryo development. Cervix connects uterus with vagina.

4 Marks Q14. Explain the significance of labelling diagrams in Science.

Labelling helps identify structures, understand their positions and functions, and communicate scientific information clearly. Diagram-based questions are also important in board examinations.

4 Marks Q15. Draw and label the structure of a sperm.

The diagram should show head, nucleus, middle piece and tail. The head contains the nucleus, middle piece contains mitochondria and tail provides movement.

5 Marks Q16. Explain fertilisation and implantation with a flow diagram.

Sperm + Ovum → Zygote → Embryo → Implantation Fertilisation usually occurs in the fallopian tube. The developing embryo moves towards the uterus and becomes implanted in the uterine lining.

5 Marks Q17. Explain the menstrual cycle using a diagram.

The menstrual cycle includes menstruation, follicular phase, ovulation and luteal phase. Hormonal changes control development of follicles, ovulation and preparation of the uterine lining.

5 Marks Q18. Explain the structure and functions of the female reproductive system.

Ovaries produce ova and hormones. Fallopian tubes receive and transport the ovum. Uterus provides the site for implantation and development. Cervix forms the lower opening of uterus and vagina forms the birth canal.

5 Marks Q19. Explain the structure and functions of the male reproductive system.

Testes produce sperm and testosterone. Epididymis supports maturation and storage of sperm. Vas deferens transports sperm. Seminal vesicles and prostate add secretions. Urethra carries semen during ejaculation.

5 Marks Q20. Explain any five important diagrams from Chapter 8.

Important diagrams include flower structure, male reproductive system, female reproductive system, sperm structure and menstrual cycle/fertilisation sequence.

6 Marks Q21. Draw and explain a labelled diagram of the human male reproductive system.

The diagram should label testes, scrotum, epididymis, vas deferens, seminal vesicles, prostate gland, urethra and penis. Testes produce sperm and testosterone, while ducts transport sperm and accessory glands add secretions.

6 Marks Q22. Draw and explain a labelled diagram of the human female reproductive system.

The diagram should label ovaries, fallopian tubes, uterus, endometrium, cervix and vagina. Ovaries produce ova; fallopian tubes transport ova; uterus supports implantation and embryo development.

6 Marks Q23. Explain the structure of a flower and the role of each reproductive part.

Stamen is the male reproductive part and consists of filament and anther. Anther produces pollen grains. Pistil/carpel is the female reproductive part and consists of stigma, style and ovary. Stigma receives pollen and ovary contains ovules.

6 Marks Q24. Explain fertilisation in humans with a suitable flow diagram.

Sperm and ovum are haploid gametes. Their fusion usually occurs in the fallopian tube and forms a diploid zygote. The zygote divides to form an embryo, which later implants in the uterine lining.

6 Marks Q25. Explain the menstrual cycle with its major phases.

The cycle can be described through menstruation, follicular phase, ovulation and luteal phase. FSH supports follicular development, an LH surge triggers ovulation, and progesterone helps maintain the uterine lining after ovulation.

6 Marks Q26. Compare male and female reproductive systems.

Male	Female
Testes produce sperm.	Ovaries produce ova.
Testes produce testosterone.	Ovaries produce estrogen and progesterone.
Sperm are generally produced continuously after puberty.	Ovarian cycles and ovulation occur cyclically.
Penis transfers semen.	Uterus supports implantation and embryo development.

6 Marks Q27. Explain asexual reproduction with suitable diagrams/examples.

Asexual reproduction generally involves one parent and no gamete fusion. Binary fission occurs in Amoeba, budding in Hydra, fragmentation in Spirogyra, regeneration in Planaria and vegetative propagation in plants.

6 Marks Q28. Explain the sequence from pollination to seed formation.

Pollen reaches stigma during pollination. A pollen tube grows through the style towards an ovule. Male gamete reaches the female gamete and fertilisation produces a zygote. The ovule generally develops into a seed and ovary generally develops into a fruit.

6 Marks Q29. Explain the importance of diagrams in understanding reproduction.

Diagrams show the structure, relative position and connections of reproductive organs. They make processes such as pollination, fertilisation, implantation and menstrual-cycle changes easier to understand and help answer diagram-based examination questions.

6 Marks Q30. Draw and label any two reproductive-system diagrams and explain their functions.

Students may draw the male and female reproductive systems. Male organs produce and transport sperm, while female organs produce ova and provide the site for fertilisation, implantation and development of the embryo.

16. Assertion–Reason – Diagram Based

Q1.
Assertion: Anther is part of the male reproductive structure of a flower.
Reason: Anther produces pollen grains.

Answer: Both A and R are true, and R correctly explains A.

Q2.
Assertion: Fertilisation in humans usually occurs in the uterus.
Reason: Implantation occurs in the uterine lining.

Answer: Assertion is false, but Reason is true.

Q3.
Assertion: The tail of sperm helps in movement.
Reason: Sperm needs to move towards the ovum.

Answer: Both A and R are true, and R correctly explains A.

Q4.
Assertion: Ovary of a flower contains ovules.
Reason: Ovules contain the female reproductive structures involved in sexual reproduction.

Answer: Both A and R are true.

Q5.
Assertion: Human gametes normally contain 46 chromosomes.
Reason: Gametes are haploid.

Answer: Assertion is false, but Reason is true.

17. HOTS / Competency-Based Questions

HOTS 1. A diagram shows pollen grains on the stigma but no zygote. What stage has occurred and what is still required?

Pollination has occurred. Fertilisation is still required for fusion of male and female gametes and formation of a zygote.

HOTS 2. If the fallopian tube is blocked, which reproductive event may be affected?

The normal meeting of sperm and ovum may be prevented, so fertilisation may be affected.

HOTS 3. Why is the scrotum located outside the main body cavity?

It helps maintain the testes at a temperature slightly lower than normal body temperature, which is suitable for sperm formation.

HOTS 4. A flower has anther and filament but no stigma. Which reproductive process is likely to be affected?

The flower would not have a normal stigma to receive pollen, so successful pollination and subsequent fertilisation would be affected.

HOTS 5. Why is implantation shown after fertilisation in a reproductive diagram?

Fertilisation produces a zygote. The developing embryo then travels towards the uterus and implants in the uterine lining.

18. CBSE Golden Points – Diagrams

• Stamen = Filament + Anther.
• Pistil/Carpel = Stigma + Style + Ovary.
• Anther produces pollen grains.
• Ovary contains ovules.
• Pollination = transfer of pollen from anther to stigma.
• Fertilisation = fusion of male and female gametes.
• Testes produce sperm and testosterone.
• Scrotum maintains suitable temperature for sperm formation.
• Epididymis supports sperm maturation and storage.
• Vas deferens transports sperm.
• Ovaries produce ova and reproductive hormones.
• Fallopian tube is the usual site of fertilisation.
• Uterine lining is the site of implantation.
• Sperm head contains nucleus.
• Sperm middle piece contains many mitochondria.
• Sperm tail helps movement.
• Human gametes normally contain 23 chromosomes.
• Human zygote normally contains 46 chromosomes.
• Binary fission – Amoeba.
• Budding – Hydra.
• Fragmentation – Spirogyra.
• Regeneration – Planaria.

19. Diagram Memory Tricks

🌸 Flower Trick

S-P-S-P
Sepal → Petal → Stamen → Pistil

---

♂ Male System

T-E-V-U-P
Testis → Epididymis → Vas deferens → Urethra → Penis

---

♀ Female System

O-F-U-C-V
Ovary → Fallopian tube → Uterus → Cervix → Vagina

---

🧬 Human Reproduction Flow

Sperm + Ovum → Zygote → Embryo → Implantation

20. Last-Minute Labelling Practice

Fill in the blanks:

1. Pollen grains are produced by ________.
2. The receptive part of carpel is ________.
3. The female reproductive organ is ________.
4. The male reproductive organ is ________.
5. The organ producing ova is ________.
6. The usual site of fertilisation in humans is ________.
7. Implantation occurs in the ________.
8. The sperm's locomotory structure is ________.
9. The sperm's energy-producing middle piece contains many ________.
10. The male gamete is called ________.
11. The female gamete is called ________.
12. Fusion of gametes forms a ________.

Answers: 1. Anther
2. Stigma
3. Pistil/Carpel
4. Stamen
5. Ovary
6. Fallopian tube
7. Uterine lining / Endometrium
8. Tail
9. Mitochondria
10. Sperm
11. Ovum
12. Zygote

21. One-Page Quick Revision

Diagram	Must Learn Labels
Flower	Sepal, Petal, Anther, Filament, Stigma, Style, Ovary, Ovule
Male System	Testis, Scrotum, Epididymis, Vas deferens, Seminal vesicle, Prostate, Urethra, Penis
Female System	Ovary, Fallopian tube, Uterus, Endometrium, Cervix, Vagina
Sperm	Head, Nucleus, Middle piece, Mitochondria, Tail
Menstrual Cycle	Menstruation, Follicular phase, Ovulation, Luteal phase
Fertilisation	Sperm, Ovum, Zygote, Embryo, Implantation
Asexual Reproduction	Binary fission, Budding, Fragmentation, Regeneration

🌸 Flower → Pollination → Fertilisation → Seed

♂ Sperm + ♀ Ovum → Zygote → Embryo → Implantation

Asexual Reproduction → One Parent → No Gamete Fusion

🎯 Chapter 8 Diagram Master Revision Complete!

Important Diagrams ✔ | Labelling ✔ | MCQs ✔ | Subjective Questions ✔ | Assertion–Reason ✔ | HOTS ✔ | Memory Tricks ✔

Exam Focus: Draw neat diagrams, use straight label lines, write correct spellings and label every required part.

Class 10th Science Chapter 7 – How Do Organisms Reproduce? | Sexually Transmitted Diseases

How Do Organisms Reproduce? | Sexually Transmitted Diseases

Class 10 Science | Chapter 8 | CBSE + Foundation + Competitive

यौन संचारित रोग (STDs / STIs) | Transmission | Symptoms | Prevention | Treatment

How Do Organisms Reproduce? | Sexually Transmitted Diseases

1. Sexually Transmitted Diseases – Introduction

English:
Sexually transmitted diseases (STDs), also called sexually transmitted infections (STIs), are infections that can spread mainly through sexual contact with an infected person.

हिन्दी:
Sexually Transmitted Diseases (STDs) या Sexually Transmitted Infections (STIs) ऐसे संक्रमण हैं जो मुख्य रूप से संक्रमित व्यक्ति के साथ यौन संपर्क के माध्यम से फैल सकते हैं।

CBSE Important Point: STIs are an important part of reproductive health because untreated infections may affect reproductive organs, fertility and overall health.

हिन्दी: STIs reproductive health का महत्वपूर्ण भाग हैं क्योंकि बिना उपचार के कुछ संक्रमण reproductive organs, fertility तथा overall health को प्रभावित कर सकते हैं।

2. Important Sexually Transmitted Infections

STI / Disease	Cause	Important Information
Gonorrhoea	Bacterium	Can affect the reproductive and urinary tract.
Syphilis	Bacterium	Can progress through different stages if untreated.
Genital Herpes	Virus	May cause painful blisters or sores.
HIV Infection	Human Immunodeficiency Virus	Attacks the immune system.
AIDS	Associated with advanced HIV infection	Acquired Immunodeficiency Syndrome.

3. Bacterial and Viral STIs

Category	Examples	Key Point
Bacterial	Gonorrhoea, Syphilis	Some bacterial STIs can be treated with appropriate antibiotics prescribed by a healthcare professional.
Viral	HIV infection, Genital Herpes	Antibiotics do not treat viral infections.

Important: Antibiotics are medicines mainly used against bacterial infections. They do not cure viral infections such as HIV infection.

महत्वपूर्ण: Antibiotics मुख्य रूप से bacterial infections के विरुद्ध उपयोग की जाती हैं। ये HIV जैसे viral infections को cure नहीं करतीं।

4. How Do Sexually Transmitted Diseases Spread?

STIs can spread through certain types of exposure, including:

• Unprotected sexual contact with an infected person.
• Contact with infected blood in certain circumstances.
• Sharing contaminated needles or syringes.
• Mother-to-child transmission of certain infections during pregnancy, childbirth or breastfeeding, depending on the infection and circumstances.

हिन्दी:

• संक्रमित व्यक्ति के साथ असुरक्षित यौन संपर्क।
• कुछ परिस्थितियों में संक्रमित रक्त के संपर्क में आने से।
• दूषित needles या syringes साझा करने से।
• कुछ infections में माँ से बच्चे तक संक्रमण पहुँच सकता है।

5. HIV – Transmission

HIV can be transmitted through:

1. Unprotected sexual contact with an infected person.
2. Exposure to infected blood.
3. Sharing contaminated needles or syringes.
4. Mother-to-child transmission in certain circumstances.

🚫 HIV Does NOT Spread Through Ordinary Social Contact

HIV is not spread through:

• Handshake – हाथ मिलाने से नहीं
• Hugging – गले मिलने से नहीं
• Sharing food – भोजन साझा करने से नहीं
• Sitting together – साथ बैठने से नहीं
• Ordinary classroom contact – सामान्य classroom contact से नहीं

Important: A person living with HIV should not be discriminated against.

6. Animated Concept Diagram – STI Transmission & Prevention

7. Common Symptoms of STIs

Some STIs may cause:

• Unusual discharge from reproductive organs.
• Pain or burning during urination.
• Genital sores or ulcers.
• Blisters around genital areas.
• Itching or irritation.
• Pelvic pain in some cases.
• Fever or swollen lymph nodes in some infections.

Very Important: Some STIs may cause few or no obvious symptoms. Therefore: “No symptoms” does not always mean “No infection”.

हिन्दी: कुछ STIs में स्पष्ट लक्षण दिखाई नहीं देते। इसलिए केवल symptoms न होने के आधार पर infection की अनुपस्थिति निश्चित नहीं की जा सकती।

8. Effects of Untreated STIs

Untreated STIs may cause:

• Damage to reproductive organs.
• Infertility.
• Pelvic inflammatory disease in some cases.
• Pregnancy-related complications.
• Transmission of infection to a newborn in certain infections.
• Long-term health complications.

9. Prevention of Sexually Transmitted Diseases

Important preventive measures:

1. Use condoms correctly and consistently.
2. Avoid sharing needles or syringes.
3. Use properly screened blood for transfusion.
4. Get tested when there is a risk of infection.
5. Seek medical advice if symptoms or possible exposure occur.
6. Complete prescribed treatment.
7. Follow safer sexual practices.

10. Role of Condoms in STI Prevention

English: Condoms are barrier contraceptive methods. When used correctly and consistently, they can reduce the risk of pregnancy and many sexually transmitted infections.

हिन्दी: Condom एक barrier contraceptive method है। इसका सही और नियमित उपयोग pregnancy तथा कई STIs के risk को कम कर सकता है।

Remember: Condoms reduce risk but do not provide 100% protection against every STI, particularly infections transmitted through uncovered skin-to-skin contact.

11. STI Testing and Diagnosis

STIs can be diagnosed through appropriate medical evaluation and laboratory tests. Depending on the infection, tests may include:

• Blood tests
• Urine tests
• Swab tests
• Other specific laboratory tests

हिन्दी: STI की diagnosis के लिए doctor symptoms, medical history और आवश्यकता के अनुसार laboratory tests की सहायता लेते हैं।

12. Treatment of STIs

Treatment depends on the organism causing the infection.

Infection Type	General Treatment Principle
Bacterial	Some bacterial STIs can be treated with appropriate prescribed antibiotics.
Viral	Antibiotics do not work against viruses; specific medical management is required.
HIV	Managed with antiretroviral therapy and regular medical care.

Never self-medicate. Suspected STI should be evaluated by a qualified healthcare professional.

स्वयं दवा न लें। संदिग्ध STI की जाँच और treatment qualified healthcare professional की सलाह से होना चाहिए।

13. Difference Between HIV and AIDS

HIV	AIDS
Human Immunodeficiency Virus	Acquired Immunodeficiency Syndrome
It is a virus.	It is an advanced disease condition associated with severe immune-system damage.
It attacks the immune system.	Untreated HIV infection can progress to AIDS.

14. STI and Reproductive Health

Reproductive Health: Physical, mental and social well-being related to the reproductive system and its functions.

प्रजनन स्वास्थ्य: प्रजनन तंत्र तथा उससे संबंधित कार्यों के संदर्भ में शारीरिक, मानसिक एवं सामाजिक कल्याण को reproductive health कहा जाता है।

STI prevention is an important component of reproductive health.

15. Importance of Awareness

Correct awareness helps people to:

• Understand STI transmission.
• Follow safer practices.
• Recognise possible symptoms.
• Seek testing when required.
• Take timely treatment.
• Prevent further transmission.
• Avoid stigma and discrimination.

16. 30 MCQs – CBSE + Foundation + Competitive

Q1. STIs are mainly associated with:

A) Digestive system

B) Sexual contact and reproductive health

C) Skeletal system

D) Respiratory system

Answer: B

Q2. HIV stands for:

A) Human Immunodeficiency Virus

B) Human Infection Virus

C) Human Immune Variation

D) Human Internal Virus

Answer: A

Q3. AIDS is associated with:

A) HIV infection

B) Malaria

C) Cholera

D) Typhoid

Answer: A

Q4. Which is a bacterial STI?

A) Gonorrhoea

B) HIV infection

C) Genital herpes

D) Influenza

Answer: A

Q5. Which of the following is viral?

A) Syphilis

B) Gonorrhoea

C) HIV infection

D) Bacterial pneumonia

Answer: C

Q6. Which contraceptive can reduce the risk of many STIs?

A) Condom

B) Copper-T

C) Oral pill only

D) Tubectomy

Answer: A

Q7. HIV is NOT spread through:

A) Contaminated needles

B) Infected blood

C) Certain sexual exposures

D) Handshake

Answer: D

Q8. Antibiotics mainly act against:

A) Viruses

B) Bacteria

C) Hormones

D) Vitamins

Answer: B

Q9. Which is caused by a bacterium?

A) Syphilis

B) HIV

C) Genital herpes

D) AIDS

Answer: A

Q10. The major purpose of STI awareness is:

A) Increasing infection

B) Preventing transmission and complications

C) Avoiding diagnosis

D) Avoiding hygiene

Answer: B

Q11. Which may be a symptom of an STI?

A) Genital sore

B) Increased height

C) Better eyesight

D) Stronger bones

Answer: A

Q12. Some STIs can occur without obvious symptoms.

A) True

B) False

C) Only in males

D) Only in females

Answer: A

Q13. Sharing contaminated needles may transmit:

A) HIV

B) Height

C) Diabetes only

D) Myopia

Answer: A

Q14. Which is NOT a recommended STI prevention method?

A) Testing when indicated

B) Correct condom use

C) Sharing needles

D) Medical treatment

Answer: C

Q15. Genital herpes is caused by:

A) Virus

B) Bacterium

C) Protozoan

D) Worm

Answer: A

Q16. HIV primarily affects:

A) Immune system

B) Bones

C) Hair

D) Teeth

Answer: A

Q17. Condom is a:

A) Hormonal method

B) Barrier method

C) Surgical method

D) Natural method

Answer: B

Q18. Which may be used to diagnose an STI?

A) Blood test

B) Eye colour test

C) Height measurement

D) Finger length

Answer: A

Q19. Untreated STIs may sometimes result in:

A) Infertility

B) Increased height

C) Better vision

D) Stronger teeth

Answer: A

Q20. Which statement is correct?

A) All STIs show immediate symptoms.

B) Some STIs may be asymptomatic.

C) HIV spreads by handshake.

D) Antibiotics cure HIV.

Answer: B

Q21. After a possible STI exposure, a person should:

A) Ignore it

B) Seek appropriate medical advice

C) Share medicines

D) Avoid all food

Answer: B

Q22. AIDS stands for:

A) Acquired Immunodeficiency Syndrome

B) Acquired Infection Disease System

C) Advanced Internal Disease Syndrome

D) Auto Immune Disease System

Answer: A

Q23. Which is a responsible reproductive-health practice?

A) Ignoring symptoms

B) Appropriate testing and prevention

C) Sharing needles

D) Self-medication

Answer: B

Q24. Which STI may cause genital blisters?

A) Genital herpes

B) Anaemia

C) Diabetes

D) Malaria

Answer: A

Q25. Correct condom use:

A) Can reduce the risk of many STIs

B) Always cures HIV

C) Causes HIV

D) Has no reproductive-health benefit

Answer: A

Q26. Who should provide professional STI diagnosis?

A) Random social media user

B) Qualified healthcare professional

C) Classmate

D) Untrained person

Answer: B

Q27. Which pair is correctly matched?

A) HIV – Virus

B) Gonorrhoea – Virus

C) Syphilis – Virus

D) Herpes – Bacterium

Answer: A

Q28. Which does NOT transmit HIV through ordinary contact?

A) Sharing contaminated needles

B) Infected blood exposure

C) Handshake

D) Certain sexual exposures

Answer: C

Q29. Reproductive health includes:

A) Only physical health

B) Physical, mental and social well-being

C) Only fertility

D) Only absence of infection

Answer: B

Q30. The best response to suspected STI is:

A) Ignore it

B) Seek confidential professional medical advice

C) Take someone else's medicine

D) Hide the condition permanently

Answer: B

17. 30 Subjective Questions with Answers

2 Marks Q1. What are sexually transmitted diseases?

STDs are diseases/infections that can spread mainly through sexual contact with an infected person.

2 Marks Q2. What is an STI?

STI means Sexually Transmitted Infection.

2 Marks Q3. Name two bacterial STIs.

Gonorrhoea and Syphilis.

2 Marks Q4. Name two viral infections associated with STIs.

HIV infection and Genital Herpes.

2 Marks Q5. Name one method that reduces the risk of many STIs.

Correct and consistent use of condoms.

3 Marks Q6. Write three routes through which HIV can be transmitted.

• Certain unprotected sexual exposures.
• Infected blood exposure.
• Contaminated needles or syringes.

3 Marks Q7. Why do antibiotics not cure HIV?

HIV is a virus. Antibiotics act mainly against bacteria and therefore do not cure HIV infection.

3 Marks Q8. Write three symptoms that may occur in some STIs.

Genital sores/blisters, unusual discharge and pain or burning during urination.

3 Marks Q9. Why is STI testing important?

Some STIs may have no obvious symptoms. Testing can help identify infection and allow timely treatment and prevention.

3 Marks Q10. State three preventive measures against STIs.

Correct condom use, avoiding contaminated needles and seeking testing/medical care when required.

4 Marks Q11. Differentiate between bacterial and viral STIs.

Bacterial STI	Viral STI
Caused by bacteria.	Caused by viruses.
Examples: Gonorrhoea, Syphilis.	Examples: HIV infection, Genital Herpes.
Some can be treated with appropriate antibiotics.	Antibiotics do not treat viral infections.

4 Marks Q12. Explain four methods of preventing STIs.

• Correct and consistent condom use.
• Avoid sharing needles and syringes.
• Use properly screened blood.
• Testing and timely medical care.

4 Marks Q13. Why are untreated STIs dangerous?

Untreated STIs may damage reproductive organs, affect fertility, cause pregnancy-related complications and lead to long-term health problems.

4 Marks Q14. Explain the importance of condoms in reproductive health.

Condoms are barrier methods that help prevent pregnancy and, when used correctly and consistently, reduce the risk of many STIs.

4 Marks Q15. Why should people living with HIV not be discriminated against?

HIV does not spread through ordinary social contact such as hugging or handshaking. Discrimination can harm mental well-being and discourage people from seeking healthcare.

5 Marks Q16. Explain the major routes of HIV transmission.

HIV may spread through certain unprotected sexual exposures, infected blood, contaminated needles/syringes and mother-to-child transmission in certain circumstances.

5 Marks Q17. Explain the importance of early diagnosis of STIs.

Early diagnosis allows appropriate treatment, reduces complications, helps prevent further transmission and protects reproductive health.

5 Marks Q18. Explain the role of awareness in STI prevention.

Awareness helps people understand transmission, follow safer practices, recognise possible symptoms, seek testing and avoid myths and discrimination.

5 Marks Q19. Explain the relationship between reproductive health and STI prevention.

Preventing and treating STIs protects reproductive organs, fertility and overall physical, mental and social well-being.

5 Marks Q20. Why should self-medication be avoided in suspected STIs?

Different infections require different treatments. Incorrect medicines can delay proper treatment, cause side effects and contribute to antimicrobial resistance.

6 Marks Q21. Explain STIs, their transmission, symptoms and prevention.

STIs are infections that can spread mainly through sexual contact. Examples include gonorrhoea, syphilis, genital herpes and HIV infection. They may spread through certain sexual exposures, infected blood and contaminated needles. Some infections may cause discharge, pain, sores or blisters, while others may show few or no symptoms. Prevention includes safer sexual practices, correct condom use, avoiding contaminated needles, testing and timely medical care.

6 Marks Q22. Explain the difference between HIV infection and AIDS.

HIV is the Human Immunodeficiency Virus. It attacks the immune system. AIDS stands for Acquired Immunodeficiency Syndrome. It is an advanced disease condition associated with severe immune-system damage. Untreated HIV infection can progress to AIDS. Appropriate antiretroviral therapy can control HIV and reduce the risk of progression.

6 Marks Q23. Discuss the role of condoms in preventing pregnancy and STIs.

Condoms are barrier contraceptives. They reduce the possibility of sperm reaching the ovum and therefore help prevent pregnancy. Correct and consistent use also reduces exposure to infected genital fluids and lowers the risk of many STIs. However, condoms do not provide absolute protection against every STI.

6 Marks Q24. Explain why some STIs remain undiagnosed.

Some STIs can produce no obvious symptoms or only mild symptoms. Therefore, a person may not realise that they are infected. Lack of awareness, stigma and absence of testing can delay diagnosis.

6 Marks Q25. Describe major preventive strategies against STIs.

1. Correct and consistent condom use.
2. Safer sexual practices.
3. Avoid sharing needles and syringes.
4. Use properly screened blood.
5. Testing when there is a risk of infection.
6. Timely professional medical care.

6 Marks Q26. Explain how untreated STIs can affect reproductive health.

Some untreated STIs may cause inflammation and damage to reproductive organs. They can contribute to infertility, pregnancy complications and transmission to newborns in certain infections.

6 Marks Q27. Explain why HIV does not spread through ordinary social contact.

HIV requires specific routes of transmission such as certain sexual exposures, infected blood or contaminated needles. Handshaking, hugging, sitting together and sharing food do not provide these routes.

6 Marks Q28. Explain the importance of confidential medical counselling.

Confidential counselling allows a person to discuss symptoms or possible exposure without fear. It helps with testing, diagnosis, treatment and prevention while protecting privacy and dignity.

6 Marks Q29. “I have no symptoms, so I cannot have an STI.” Evaluate this statement.

The statement is incorrect. Some STIs may be asymptomatic or have very mild symptoms. Therefore, appropriate testing may be necessary after a possible exposure.

6 Marks Q30. “STI prevention is an important part of reproductive health.” Justify.

STI prevention protects reproductive organs, fertility and overall health. It reduces transmission, prevents complications, supports timely treatment and promotes responsible reproductive health practices.

18. Assertion–Reason Questions

Q1.
Assertion (A): Condoms can reduce the risk of many STIs.
Reason (R): Condoms act as barrier methods.

Answer: Both A and R are true, and R correctly explains A.

Q2.
Assertion (A): Antibiotics can cure HIV infection.
Reason (R): HIV is caused by a virus.

Answer: A is false, but R is true.

Q3.
Assertion (A): Some STIs may remain undiagnosed.
Reason (R): Some STIs may have few or no obvious symptoms.

Answer: Both A and R are true, and R correctly explains A.

Q4.
Assertion (A): HIV spreads through handshaking.
Reason (R): HIV requires specific routes of transmission.

Answer: A is false, but R is true.

Q5.
Assertion (A): Untreated STIs may affect reproductive health.
Reason (R): Some infections may damage reproductive organs.

Answer: Both A and R are true, and R correctly explains A.

19. HOTS / Competency-Based Questions

HOTS 1. A person has no symptoms after a possible STI exposure. Can the person conclude that there is no infection?

Answer: No. Some STIs may be asymptomatic. Appropriate testing and professional medical advice may be required.

HOTS 2. Why should a person not use someone else's antibiotic prescription for an STI?

The infection may be caused by a different organism and the medicine or dose may be inappropriate. Misuse may also contribute to antimicrobial resistance.

HOTS 3. A student believes HIV spreads through sharing lunch with an infected person. How will you correct the misconception?

HIV does not spread through sharing food, handshaking, hugging or sitting together. It spreads through specific routes such as certain sexual exposures, infected blood and contaminated needles.

HOTS 4. Why is STI prevention both an individual and public-health responsibility?

Prevention protects an individual's health and reproductive function and also reduces transmission of infection within the community.

HOTS 5. Why may delaying treatment of an STI be harmful?

Delayed treatment may allow the infection to persist, increase complications and increase the possibility of transmission to others.

20. Important Diagram / Concept Labelling

Important Labels: STI Transmission Symptoms Testing Diagnosis Treatment Prevention Reproductive Health

21. CBSE Golden Points

• STI = Sexually Transmitted Infection.
• STD = Sexually Transmitted Disease.
• Gonorrhoea is a bacterial STI.
• Syphilis is a bacterial STI.
• Genital herpes is a viral infection.
• HIV = Human Immunodeficiency Virus.
• AIDS = Acquired Immunodeficiency Syndrome.
• HIV attacks the immune system.
• Antibiotics do not cure HIV.
• Condoms are barrier methods.
• Condoms can reduce the risk of many STIs.
• Some STIs may be asymptomatic.
• Untreated STIs may cause reproductive-health complications.
• Contaminated needles can transmit blood-borne infections.
• Properly screened blood reduces blood-borne transmission risk.
• HIV does not spread through ordinary social contact.
• Testing can be important after a possible exposure.
• Self-medication should be avoided.
• Timely professional medical care is important.
• STI prevention is an important part of reproductive health.

22. Easy Memory Tricks

🧠 STI Memory Trick – BVP

B → Bacterial
Gonorrhoea + Syphilis

V → Viral
HIV Infection + Genital Herpes

P → Prevention
Condom + Testing + Safe Practices + Medical Care

---

🧠 Prevention Trick – “STEPS”

S → Safer practices

T → Testing when required

E → Education / Awareness

P → Prevention

S → Seek medical care

23. One-Line Revision

STIs → Awareness → Prevention → Testing → Treatment → Healthy Reproductive Life

One-Line Summary: STIs can affect reproductive and overall health, but correct information, safer practices, condom use, appropriate testing and timely professional medical care can reduce their impact.

हिन्दी: STIs reproductive तथा सामान्य स्वास्थ्य को प्रभावित कर सकते हैं, लेकिन सही जानकारी, सुरक्षित व्यवहार, condom का उपयोग, आवश्यक testing और समय पर medical care इनके प्रभाव को कम करने में सहायता करते हैं।

24. Quick Revision Table

Topic	Key Point
STI	Sexually Transmitted Infection
STD	Sexually Transmitted Disease
Gonorrhoea	Bacterial STI
Syphilis	Bacterial STI
Genital Herpes	Viral STI
HIV	Virus affecting the immune system
AIDS	Advanced syndrome associated with severe immune-system damage
Condom	Barrier method; reduces pregnancy and many STI risks
Testing	Important because some infections may have no obvious symptoms
Prevention	Safer practices, condoms, sterile needles, screened blood and testing
Treatment	Depends on the causative organism and requires appropriate medical care

🎯 Chapter 8 – Topic Complete!

Sexually Transmitted Diseases | Reproductive Health | Prevention | Testing | Treatment

Concepts ✔ | MCQs ✔ | Subjective ✔ | Assertion–Reason ✔ | HOTS ✔ | Diagram ✔ | Revision ✔

Class 10th Science Chapter 7 – How Do Organisms Reproduce? | Fertilisation, Implantation and Pregnancy

How Do Organisms Reproduce? | Fertilisation, Implantation and Pregnancy

Class 10 Science | Chapter 7 | CBSE + Foundation + Competitive

Fertilisation • Zygote • Embryo • Implantation • Placenta • Pregnancy

How Do Organisms Reproduce? | Fertilisation, Implantation and Pregnancy

1. Introduction | परिचय

Fertilisation is the process in which the male gamete (sperm) fuses with the female gamete (ovum) to form a zygote.

निषेचन (Fertilisation) वह प्रक्रिया है जिसमें नर युग्मक (शुक्राणु) और मादा युग्मक (अंडाणु) का संलयन होकर युग्मनज (Zygote) बनता है।

Sperm + Ovum → Zygote
शुक्राणु + अंडाणु → युग्मनज

In human beings, fertilisation normally occurs in the fallopian tube (oviduct), not in the uterus.

मनुष्य में सामान्यतः निषेचन फैलोपियन ट्यूब (अंडवाहिनी) में होता है, गर्भाशय में नहीं।

CBSE Golden Point: Do not confuse fertilisation with implantation.
Fertilisation = formation of zygote.
Implantation = attachment of embryo to the uterine lining.

2. Gametes and Chromosome Number | युग्मक एवं गुणसूत्र संख्या

Cell / कोशिका	Chromosome Number	Type
Human body cell / मानव शरीर कोशिका	46	Diploid (2n)
Sperm / शुक्राणु	23	Haploid (n)
Ovum / अंडाणु	23	Haploid (n)
Zygote / युग्मनज	46	Diploid (2n)

23 + 23 = 46

The reduction of chromosome number in gametes is important because fertilisation restores the diploid chromosome number.

युग्मकों में गुणसूत्र संख्या आधी होने के कारण निषेचन के बाद सामान्य द्विगुणित गुणसूत्र संख्या पुनः स्थापित हो जाती है।

3. Fertilisation in Humans | मनुष्य में निषेचन

Ovulation
अंडोत्सर्जन

→

Sperm reaches
Fallopian Tube

→

Fusion of Gametes

→

Zygote

During ovulation, an ovum is released from an ovary. Sperm deposited in the female reproductive tract can travel through the cervix and uterus towards the fallopian tube.

अंडोत्सर्जन के दौरान अंडाशय से अंडाणु निकलता है। महिला प्रजनन तंत्र में प्रवेश किए हुए शुक्राणु गर्भाशय ग्रीवा और गर्भाशय से होते हुए फैलोपियन ट्यूब तक पहुँच सकते हैं।

If a sperm successfully fuses with the ovum, fertilisation occurs and a zygote is formed.

यदि कोई शुक्राणु अंडाणु से सफलतापूर्वक संलयित हो जाता है, तो निषेचन होता है और युग्मनज बनता है।

Important: Only one sperm normally fertilises the ovum. After fertilisation, mechanisms prevent additional sperm from entering the egg.

4. Fertilisation to Implantation – Animated Diagram

5. Development of Zygote | युग्मनज का विकास

Zygote

→

Cell Division

→

Embryo

→

Implantation

→

Foetus

After fertilisation, the zygote begins repeated cell divisions. As development continues, the group of cells becomes an embryo.

निषेचन के बाद युग्मनज में बार-बार कोशिका विभाजन होता है। विकास के साथ कोशिकाओं का समूह भ्रूण (Embryo) में विकसित होता है।

The developing embryo moves towards the uterus and becomes attached to the thickened lining of the uterus.

विकसित होता भ्रूण गर्भाशय की ओर जाता है और गर्भाशय की मोटी हुई आंतरिक परत से जुड़ जाता है।

6. Implantation | आरोपण

Implantation is the process by which the developing embryo becomes attached to the lining of the uterus, called the endometrium.

आरोपण (Implantation) वह प्रक्रिया है जिसमें विकसित होता हुआ भ्रूण गर्भाशय की आंतरिक परत एंडोमेट्रियम से जुड़ जाता है।

Fertilisation → Zygote → Cell Division → Embryo → Implantation

Remember:
Fertilisation occurs in the fallopian tube.
Implantation occurs in the uterus.

The uterine lining becomes thick and richly supplied with blood vessels so that it can support the developing embryo.

7. Pregnancy | गर्भावस्था

Pregnancy begins after successful implantation and establishment of the developing embryo in the uterus.

सफल आरोपण और गर्भाशय में भ्रूण के विकास के साथ गर्भावस्था की स्थापना होती है।

During pregnancy, the embryo undergoes extensive growth and differentiation. As development progresses, the developing baby is commonly called a foetus after the early embryonic stage.

गर्भावस्था के दौरान भ्रूण में तीव्र वृद्धि और विभेदन होता है। प्रारंभिक भ्रूणीय अवस्था के बाद विकसित हो रहे शिशु को सामान्यतः भ्रूण (Foetus) कहा जाता है।

8. Placenta | अपरा / प्लेसेंटा

The placenta is a specialised temporary organ that develops between maternal and foetal tissues during pregnancy.

प्लेसेंटा गर्भावस्था के दौरान मातृ और भ्रूणीय ऊतकों के बीच बनने वाला एक विशेष अस्थायी अंग है।

It provides a large surface for exchange of materials between the mother and developing foetus.

यह माँ और विकसित होते भ्रूण के बीच पदार्थों के आदान-प्रदान के लिए एक बड़ा सतह क्षेत्र प्रदान करता है।

Substance	General Direction
Oxygen	Mother → Foetus
Nutrients	Mother → Foetus
Carbon dioxide	Foetus → Mother
Some metabolic wastes	Foetus → Mother

Maternal and foetal blood do not normally mix directly; exchange occurs across the placental interface.

9. Hormonal Support During Pregnancy | गर्भावस्था में हार्मोनल भूमिका

After ovulation, the corpus luteum produces progesterone, which helps maintain the uterine lining.

During pregnancy, the placenta also becomes an important endocrine tissue and produces hormones that help maintain pregnancy and prepare the mother's body for childbirth and lactation.

Hormone	Main Role
Progesterone	Helps maintain uterine lining
Estrogen	Supports growth of reproductive tissues and pregnancy-related changes
hCG	Supports corpus luteum during early pregnancy
hCG is also detected in pregnancy tests	Useful marker of pregnancy

10. What Happens if Fertilisation Does Not Occur?

No Fertilisation

→

Corpus Luteum Degenerates

→

Hormone Levels Fall

→

Uterine Lining Breaks Down

→

Menstruation

If fertilisation does not occur, the uterine lining is no longer maintained at the same level. Hormonal changes lead to its shedding, resulting in menstruation.

यदि निषेचन नहीं होता है, तो हार्मोनल परिवर्तन के कारण गर्भाशय की परत टूटकर बाहर निकलती है, जिसे मासिक धर्म कहते हैं।

11. Fertilisation, Implantation and Menstruation – Difference

Process	Meaning	Location
Fertilisation	Fusion of sperm and ovum	Usually fallopian tube
Implantation	Attachment of embryo to uterine lining	Uterus
Menstruation	Shedding of uterine lining when pregnancy has not been established	Uterus / reproductive tract

12. Early Embryonic Development | प्रारंभिक भ्रूणीय विकास

The zygote undergoes mitotic cell divisions called cleavage. The number of cells increases while the early embryo moves towards the uterus.

The cells then undergo differentiation and organise into tissues and organs. Development continues throughout pregnancy.

🧠 Memory Trick:

F → Z → D → E → I → P
F = Fertilisation
Z = Zygote
D = Division
E = Embryo
I = Implantation
P = Pregnancy

13. Important Developmental Terms

Term	Meaning
Gamete	Haploid reproductive cell
Fertilisation	Fusion of male and female gametes
Zygote	First diploid cell formed after fertilisation
Embryo	Developing organism during early developmental stage
Implantation	Attachment of embryo to uterine lining
Foetus	Developing baby at a later stage of pregnancy
Placenta	Organ for exchange between mother and developing foetus
Pregnancy	Period of development of the embryo/foetus in the uterus

14. 30 MCQs | Multiple Choice Questions

Question 1. Fertilisation in human beings normally occurs in:

A) Ovary

B) Fallopian tube

C) Uterus

D) Vagina

Answer: B) Fallopian tube

Question 2. Fusion of sperm and ovum produces:

A) Embryo

B) Foetus

C) Zygote

D) Placenta

Answer: C) Zygote

Question 3. A normal human sperm contains:

A) 23 chromosomes

B) 46 chromosomes

C) 44 chromosomes

D) 92 chromosomes

Answer: A) 23 chromosomes

Question 4. Implantation occurs in the:

A) Ovary

B) Fallopian tube

C) Uterus

D) Cervix

Answer: C) Uterus

Question 5. The uterine lining is called:

A) Myometrium

B) Endometrium

C) Perimetrium

D) Epididymis

Answer: B) Endometrium

Question 6. The chromosome number of a human ovum is:

A) 46

B) 92

C) 23

D) 44

Answer: C) 23

Question 7. The zygote is:

A) Haploid

B) Diploid

C) Triploid

D) Tetraploid

Answer: B) Diploid

Question 8. Which structure provides exchange of materials between mother and foetus?

A) Placenta

B) Ovary

C) Cervix

D) Urethra

Answer: A) Placenta

Question 9. Which hormone helps maintain the uterine lining?

A) Insulin

B) Progesterone

C) Adrenaline

D) Thyroxine

Answer: B) Progesterone

Question 10. The first cell formed after fertilisation is:

A) Ovum

B) Sperm

C) Embryo

D) Zygote

Answer: D) Zygote

Question 11. Which event directly follows fertilisation?

A) Formation of zygote

B) Menopause

C) Menstruation

D) Ovulation

Answer: A) Formation of zygote

Question 12. The embryo becomes attached to:

A) Ovary

B) Endometrium

C) Epididymis

D) Testis

Answer: B) Endometrium

Question 13. Which process restores the diploid chromosome number?

A) Ovulation

B) Menstruation

C) Fertilisation

D) Implantation

Answer: C) Fertilisation

Question 14. The female gamete is:

A) Sperm

B) Ovum

C) Zygote

D) Embryo

Answer: B) Ovum

Question 15. Which structure connects the ovary to the uterus and is normally the site of fertilisation?

A) Fallopian tube

B) Cervix

C) Vagina

D) Urethra

Answer: A) Fallopian tube

Question 16. If fertilisation does not occur, the uterine lining generally:

A) Remains unchanged permanently

B) Becomes bone

C) Is shed

D) Produces sperm

Answer: C) Is shed

Question 17. The placenta mainly helps in:

A) Producing sperm

B) Exchange of substances

C) Digesting food

D) Producing urine

Answer: B) Exchange of substances

Question 18. Which is haploid?

A) Zygote

B) Body cell

C) Sperm

D) Embryo

Answer: C) Sperm

Question 19. The normal chromosome number in a human zygote is:

A) 23

B) 44

C) 46

D) 92

Answer: C) 46

Question 20. The process of attachment of embryo to the uterine wall is:

A) Fertilisation

B) Implantation

C) Ovulation

D) Menstruation

Answer: B) Implantation

Question 21. hCG is commonly associated with:

A) Pregnancy

B) Digestion

C) Respiration

D) Blood clotting

Answer: A) Pregnancy

Question 22. The developing embryo receives nutrients through the:

A) Placenta

B) Epididymis

C) Prostate

D) Ovary

Answer: A) Placenta

Question 23. Which sequence is correct?

A) Embryo → Zygote → Fertilisation → Implantation

B) Fertilisation → Zygote → Cell division → Embryo → Implantation

C) Implantation → Fertilisation → Zygote → Embryo

D) Zygote → Fertilisation → Ovulation → Embryo

Answer: B) Fertilisation → Zygote → Cell division → Embryo → Implantation

Question 24. Which organ contains the developing embryo after implantation?

A) Ovary

B) Uterus

C) Kidney

D) Testis

Answer: B) Uterus

Question 25. A sperm and an ovum are:

A) Diploid cells

B) Haploid cells

C) Triploid cells

D) Somatic tissues

Answer: B) Haploid cells

Question 26. Which hormone is produced by the corpus luteum and helps maintain the uterine lining?

A) Progesterone

B) Insulin

C) Adrenaline

D) Growth hormone

Answer: A) Progesterone

Question 27. Which one is NOT a result of fertilisation?

A) Formation of zygote

B) Restoration of diploid chromosome number

C) Fusion of gametes

D) Immediate implantation in the ovary

Answer: D) Immediate implantation in the ovary

Question 28. Which substance generally moves from foetus to mother through the placenta?

A) Oxygen

B) Carbon dioxide

C) Glucose

D) Amino acids

Answer: B) Carbon dioxide

Question 29. The embryo is formed from:

A) Zygote

B) Sperm alone

C) Ovum alone

D) Placenta alone

Answer: A) Zygote

Question 30. Which statement is correct?

A) Fertilisation normally occurs in the uterus.

B) Implantation normally occurs in the ovary.

C) Fertilisation forms a zygote.

D) Sperm contains 46 chromosomes.

Answer: C) Fertilisation forms a zygote.

15. 30 Subjective Questions with Answers

2 Marks Question 1. What is fertilisation? Where does it normally occur in humans?

Answer: Fertilisation is the fusion of male and female gametes to form a zygote. In humans, it normally occurs in the fallopian tube.

2 Marks Question 2. Define implantation.

Answer: Implantation is the attachment of the developing embryo to the thickened lining of the uterus.

2 Marks Question 3. What is a zygote?

Answer: A zygote is the diploid cell formed by the fusion of sperm and ovum during fertilisation.

2 Marks Question 4. How many chromosomes are present in a human sperm and ovum?

Answer: Both sperm and ovum contain 23 chromosomes.

2 Marks Question 5. What is the role of the placenta?

Answer: Placenta provides a surface for exchange of oxygen, nutrients and wastes between mother and developing foetus.

3 Marks Question 6. Differentiate between fertilisation and implantation.

Answer:
1. Fertilisation is fusion of sperm and ovum; implantation is attachment of embryo to uterine lining.
2. Fertilisation normally occurs in fallopian tube; implantation occurs in uterus.
3. Fertilisation forms zygote; implantation establishes the embryo in the uterus.

3 Marks Question 7. Explain the formation of a zygote.

Answer: During fertilisation, a sperm fuses with an ovum. Their nuclei combine and form a diploid cell called the zygote. It contains 46 chromosomes in humans.

3 Marks Question 8. Explain the early development of the zygote.

Answer: The zygote undergoes repeated mitotic cell divisions. The number of cells increases, forming an embryo. The developing embryo moves towards the uterus and later undergoes implantation.

3 Marks Question 9. Why are gametes haploid?

Answer: Gametes contain half the chromosome number so that fusion of male and female gametes restores the normal diploid chromosome number in the zygote.

3 Marks Question 10. What happens to the uterine lining when fertilisation does not occur?

Answer: Hormone levels fall, the thickened uterine lining breaks down and is shed from the body as menstruation.

4 Marks Question 11. Explain the sequence from fertilisation to implantation.

Answer:
1. Sperm fuses with ovum.
2. A diploid zygote is formed.
3. Zygote undergoes repeated cell division.
4. It develops into an embryo and attaches to the uterine lining during implantation.

4 Marks Question 12. Describe the importance of the placenta.

Answer:
1. Provides a large exchange surface.
2. Supplies oxygen and nutrients to the foetus.
3. Helps transfer carbon dioxide and metabolic wastes towards the mother's circulation.
4. Also functions as an endocrine tissue during pregnancy.

4 Marks Question 13. Distinguish between zygote, embryo and foetus.

Answer:
Zygote: First diploid cell formed after fertilisation.
Embryo: Early developing organism formed after repeated cell division and differentiation.
Foetus: Developing baby at a later stage of pregnancy when body structures become more recognisable.

4 Marks Question 14. Explain why fertilisation restores the chromosome number.

Answer: Sperm contains 23 chromosomes and ovum contains 23 chromosomes. Their fusion combines these sets, producing a zygote with 46 chromosomes. Thus the diploid chromosome number is restored.

4 Marks Question 15. Explain the role of progesterone during the reproductive cycle and pregnancy.

Answer: Progesterone is produced mainly by the corpus luteum after ovulation. It helps maintain the uterine lining. During pregnancy, hormonal support maintains conditions suitable for continued development.

5 Marks Question 16. Explain fertilisation in human beings in detail.

Answer:
1. Ovulation releases an ovum from an ovary.
2. Sperm travel through the female reproductive tract.
3. A sperm may reach the fallopian tube.
4. Fusion of sperm and ovum forms a zygote.
5. The zygote begins cell division and develops into an embryo.

5 Marks Question 17. Explain implantation and its importance.

Answer: Implantation is attachment of the developing embryo to the endometrium. It is important because the uterus provides a suitable environment and the placenta develops to support exchange of materials between mother and foetus.

5 Marks Question 18. Explain the role of placenta in pregnancy.

Answer:
• Provides oxygen to foetus.
• Supplies nutrients.
• Receives carbon dioxide and metabolic wastes from foetus.
• Provides an exchange surface.
• Produces hormones important for pregnancy.

5 Marks Question 19. Describe what happens after fertilisation.

Answer: A zygote forms and undergoes repeated mitotic divisions. It develops into an embryo, travels towards the uterus and implants in the endometrium. The placenta develops and the embryo continues to grow and differentiate.

5 Marks Question 20. Why is direct mixing of maternal and foetal blood normally avoided?

Answer: The placental interface allows exchange of oxygen, nutrients and wastes without requiring direct mixing of maternal and foetal blood. This provides a controlled exchange environment.

6 Marks Question 21. Describe the complete sequence from ovulation to implantation.

Answer:
1. An ovum is released from the ovary during ovulation.
2. The ovum enters the fallopian tube.
3. Sperm may reach the fallopian tube.
4. Fusion of sperm and ovum forms a zygote.
5. The zygote undergoes repeated cell division.
6. The developing embryo reaches the uterus and implants in the endometrium.

6 Marks Question 22. Explain the development of the zygote into an embryo.

Answer: The zygote undergoes repeated mitotic divisions. The number of cells increases and the cells begin to differentiate. The developing cell mass forms an early embryo. It moves towards the uterus and becomes implanted in the uterine lining. Further cell division, differentiation and organ formation continue.

6 Marks Question 23. Explain how the placenta supports the developing foetus.

Answer:
1. It provides a large exchange surface.
2. Oxygen moves from maternal blood towards foetal blood.
3. Nutrients are supplied to the foetus.
4. Carbon dioxide moves from foetus towards mother.
5. Some metabolic wastes are transferred towards maternal circulation.
6. Placenta also produces hormones that support pregnancy.

6 Marks Question 24. Explain the significance of fertilisation in sexual reproduction.

Answer:
• It brings male and female genetic material together.
• It forms the zygote.
• It restores diploid chromosome number.
• It initiates development of a new organism.
• It contributes to genetic variation because genetic material comes from two parents.
• It begins embryonic development.

6 Marks Question 25. Explain the difference between fertilisation, implantation and pregnancy.

Answer:
Fertilisation: Fusion of sperm and ovum to form zygote; normally in fallopian tube.
Implantation: Attachment of embryo to endometrium; in uterus.
Pregnancy: Period during which the developing embryo/foetus grows in the uterus.

6 Marks Question 26. Explain the hormonal importance of progesterone and hCG during early pregnancy.

Answer: Progesterone helps maintain the uterine lining. In early pregnancy, hCG supports the corpus luteum so that progesterone production can continue. This helps maintain the conditions required for the developing embryo.

6 Marks Question 27. A sperm contains 23 chromosomes and the ovum contains 23 chromosomes. Explain what happens after their fusion.

Answer: The sperm and ovum fuse during fertilisation. Their chromosome sets combine, producing a zygote with 46 chromosomes. The zygote undergoes mitotic divisions and develops into an embryo. The embryo later implants in the uterus.

6 Marks Question 28. Explain why implantation is necessary for successful pregnancy.

Answer: Implantation establishes the embryo in the uterus. The uterine lining provides support and blood supply, while the developing placenta facilitates exchange of oxygen, nutrients and wastes. Therefore, implantation is essential for continued embryonic development.

6 Marks Question 29. Explain the changes that occur when fertilisation does not take place.

Answer:
1. The ovum is not fertilised.
2. The corpus luteum eventually degenerates.
3. Progesterone and other ovarian hormone levels fall.
4. The uterine lining is no longer maintained in the same way.
5. The lining breaks down.
6. Menstruation occurs.

6 Marks Question 30. Write a detailed account of human fertilisation, implantation and pregnancy.

Answer: During ovulation an ovum is released into the fallopian tube. Sperm may reach the ovum and one sperm can fuse with it, forming a diploid zygote. The zygote undergoes repeated cell division and forms an embryo. The embryo moves into the uterus and attaches to the endometrium through implantation. A placenta develops and facilitates exchange of oxygen, nutrients and wastes between mother and foetus. The embryo continues to grow, differentiate and develop into a foetus during pregnancy.

16. HOTS / Competency-Based Questions

HOTS 1. Why does fertilisation not normally occur in the uterus?

Answer: The fallopian tube provides the usual location where sperm and ovum meet. The uterus mainly provides the environment for implantation and subsequent development.

HOTS 2. If both sperm and ovum had 46 chromosomes, what problem would arise?

Answer: Their fusion would produce a zygote with 92 chromosomes rather than the normal diploid number of 46. Therefore, meiosis must reduce chromosome number in gametes.

HOTS 3. Why is a thick uterine lining important after implantation?

Answer: It provides a suitable, well-supplied environment for the developing embryo and supports formation and functioning of the placenta.

HOTS 4. Why is the placenta described as an exchange organ?

Answer: It allows oxygen and nutrients to reach the foetus and carbon dioxide and certain wastes to move towards the mother's circulation.

HOTS 5. A pregnancy test detects hCG. Why can this hormone be used as an indicator of pregnancy?

Answer: hCG is produced during early pregnancy and supports the corpus luteum. Its presence in urine or blood can therefore indicate pregnancy.

17. Assertion–Reason Practice

Question 1.
Assertion (A): Fertilisation restores the diploid chromosome number.
Reason (R): Human sperm and ovum are haploid.

Answer: Both A and R are true, and R correctly explains A.

Question 2.
Assertion (A): Implantation occurs in the fallopian tube.
Reason (R): Fertilisation normally occurs in the fallopian tube.

Answer: A is false, but R is true.

Question 3.
Assertion (A): Placenta helps in exchange of substances.
Reason (R): The foetus requires oxygen and nutrients for growth.

Answer: Both A and R are true, and R supports A.

18. Important Diagram Labelling

Important Labels: Ovary, Fallopian Tube, Uterus, Endometrium, Cervix, Vagina.

19. CBSE Golden Points | परीक्षा के लिए महत्वपूर्ण बिंदु

✔ Fertilisation = fusion of sperm and ovum.

✔ Fertilisation normally occurs in the fallopian tube.

✔ Zygote is diploid.

✔ Human sperm = 23 chromosomes.

✔ Human ovum = 23 chromosomes.

✔ Human zygote = 46 chromosomes.

✔ Implantation occurs in the uterus.

✔ Implantation means attachment of embryo to endometrium.

✔ Placenta provides exchange of oxygen, nutrients and wastes.

✔ Progesterone helps maintain the uterine lining.

✔ hCG is associated with early pregnancy and is detected by pregnancy tests.

✔ If fertilisation does not occur, the uterine lining is shed during menstruation.

20. One-Line Revision

Ovulation → Fertilisation → Zygote → Cell Division → Embryo → Implantation → Placenta → Foetus → Pregnancy

अंडोत्सर्जन → निषेचन → युग्मनज → कोशिका विभाजन → भ्रूण → आरोपण → प्लेसेंटा → भ्रूणीय विकास → गर्भावस्था

21. Quick Summary | त्वरित पुनरावृत्ति

Fertilisation: Sperm + Ovum → Zygote

Site: Fallopian tube

Implantation: Embryo attaches to endometrium

Site of implantation: Uterus

Placenta: Exchange of materials between mother and developing foetus

Progesterone: Helps maintain uterine lining

hCG: Important early pregnancy hormone and pregnancy-test marker

Without fertilisation: Uterine lining sheds → Menstruation

Class 10 Science | How Do Organisms Reproduce?
Fertilisation • Implantation • Pregnancy • Placenta

CBSE + Foundation + Competitive Preparation