How Do Organisms Reproduce? | Puberty, Gametes and Menstrual Cycle
Class 10 Science | Chapter 8 | CBSE + Foundation + Competitive Level
🌸 Puberty, Gametes and Menstrual Cycle
1. Introduction | परिचय
English:
Puberty is the stage of life during which the body undergoes physical, hormonal and reproductive changes and becomes capable of sexual reproduction. During puberty, reproductive organs mature and secondary sexual characteristics develop.
हिन्दी:
यौवनारंभ (Puberty) जीवन की वह अवस्था है जिसमें शरीर में शारीरिक, हार्मोनल तथा जनन संबंधी परिवर्तन होते हैं और व्यक्ति प्रजनन की क्षमता प्राप्त करने लगता है। इस अवस्था में जनन अंग परिपक्व होते हैं तथा द्वितीयक लैंगिक लक्षण विकसित होते हैं।
Puberty is the stage of life during which the body undergoes physical, hormonal and reproductive changes and becomes capable of sexual reproduction. During puberty, reproductive organs mature and secondary sexual characteristics develop.
हिन्दी:
यौवनारंभ (Puberty) जीवन की वह अवस्था है जिसमें शरीर में शारीरिक, हार्मोनल तथा जनन संबंधी परिवर्तन होते हैं और व्यक्ति प्रजनन की क्षमता प्राप्त करने लगता है। इस अवस्था में जनन अंग परिपक्व होते हैं तथा द्वितीयक लैंगिक लक्षण विकसित होते हैं।
2. Puberty | यौवनारंभ
Puberty includes:
- Maturation of reproductive organs.
- Production of mature gametes begins.
- Hormonal changes become prominent.
- Secondary sexual characteristics appear.
- Rapid physical growth occurs.
- Emotional and behavioural changes may occur.
- जनन अंगों का परिपक्व होना।
- परिपक्व युग्मकों का निर्माण शुरू होना।
- हार्मोनल परिवर्तन।
- द्वितीयक लैंगिक लक्षणों का विकास।
- शरीर की तीव्र वृद्धि।
- भावनात्मक एवं व्यवहार संबंधी परिवर्तन।
3. Changes During Puberty | यौवनारंभ में परिवर्तन
| Changes in Boys | लड़कों में | Changes in Girls | लड़कियों में |
|---|---|
| Growth of facial and body hair. | Development of breasts. |
| Voice generally becomes deeper. | Growth of hair in armpits and pubic region. |
| Shoulders and muscles develop. | Changes in body shape. |
| Testes begin active sperm production. | Ovarian cycles and ovulation begin. |
| Testosterone secretion increases. | Menstrual cycles begin. |
4. Hormonal Control of Puberty | यौवनारंभ का हार्मोनल नियंत्रण
Puberty is controlled by hormonal changes involving the brain and reproductive organs.
The hypothalamus releases GnRH, which stimulates the pituitary gland.
The pituitary releases FSH and LH.
These hormones act on the gonads.
हिन्दी:
यौवनारंभ का नियंत्रण हार्मोन द्वारा होता है। हाइपोथैलेमस से GnRH निकलता है, जो पिट्यूटरी ग्रंथि को FSH तथा LH स्रावित करने के लिए प्रेरित करता है। ये हार्मोन जनन ग्रंथियों पर कार्य करते हैं।
हिन्दी:
यौवनारंभ का नियंत्रण हार्मोन द्वारा होता है। हाइपोथैलेमस से GnRH निकलता है, जो पिट्यूटरी ग्रंथि को FSH तथा LH स्रावित करने के लिए प्रेरित करता है। ये हार्मोन जनन ग्रंथियों पर कार्य करते हैं।
Hypothalamus
→
GnRH
→
Pituitary
→
FSH + LH
→
Gonads
5. Gametes | युग्मक
Gametes are specialised reproductive cells involved in sexual reproduction.
In humans:
हिन्दी:
युग्मक वे विशेष जनन कोशिकाएँ हैं जो लैंगिक जनन में भाग लेती हैं। मनुष्य में:
- Male gamete = Sperm
- Female gamete = Ovum / Egg
हिन्दी:
युग्मक वे विशेष जनन कोशिकाएँ हैं जो लैंगिक जनन में भाग लेती हैं। मनुष्य में:
- नर युग्मक = शुक्राणु
- मादा युग्मक = अंडाणु
6. Chromosome Number in Gametes | युग्मकों में गुणसूत्र
| Cell | Chromosome Number | Condition |
|---|---|---|
| Human body cell | 46 | Diploid |
| Sperm | 23 | Haploid |
| Ovum | 23 | Haploid |
| Zygote | 46 | Diploid |
23 chromosomes + 23 chromosomes = 46 chromosomes
Sperm + Ovum → Zygote
Sperm + Ovum → Zygote
7. Gamete Concept Diagram | युग्मक की अवधारणा
8. Female Gamete – Ovum | मादा युग्मक – अंडाणु
The ovum is the female gamete.
Important features:
- It is haploid.
- It normally contains 23 chromosomes.
- It carries an X chromosome as its sex chromosome.
- It fuses with a sperm during fertilisation.
9. Male Gamete – Sperm | नर युग्मक – शुक्राणु
The sperm is the male gamete.
Important features:
- It is haploid.
- It normally contains 23 chromosomes.
- It can carry either X or Y chromosome.
- It is motile due to its flagellum/tail.
10. Fertilisation | निषेचन
Fertilisation is the fusion of a male gamete and a female gamete.
In humans, fertilisation usually takes place in the fallopian tube.
The product is called a zygote.
हिन्दी:
नर युग्मक और मादा युग्मक के संलयन को निषेचन कहते हैं। मनुष्य में निषेचन सामान्यतः फैलोपियन नलिका में होता है। निषेचन के बाद युग्मनज बनता है।
हिन्दी:
नर युग्मक और मादा युग्मक के संलयन को निषेचन कहते हैं। मनुष्य में निषेचन सामान्यतः फैलोपियन नलिका में होता है। निषेचन के बाद युग्मनज बनता है।
Sperm (23) + Ovum (23) → Zygote (46)
11. Menstrual Cycle | मासिक धर्म चक्र
The menstrual cycle is a series of cyclic changes occurring in the ovaries and uterus of a reproductive-age female.
A typical cycle is often described as approximately 28 days, but cycle length varies among individuals and from cycle to cycle.
हिन्दी:
मासिक धर्म चक्र प्रजनन आयु की महिला के अंडाशय तथा गर्भाशय में होने वाले चक्रीय परिवर्तनों की श्रृंखला है। सामान्य उदाहरण के रूप में इसे लगभग 28 दिनों का बताया जाता है, लेकिन इसकी अवधि व्यक्ति-व्यक्ति और चक्र-दर-चक्र अलग हो सकती है।
हिन्दी:
मासिक धर्म चक्र प्रजनन आयु की महिला के अंडाशय तथा गर्भाशय में होने वाले चक्रीय परिवर्तनों की श्रृंखला है। सामान्य उदाहरण के रूप में इसे लगभग 28 दिनों का बताया जाता है, लेकिन इसकी अवधि व्यक्ति-व्यक्ति और चक्र-दर-चक्र अलग हो सकती है।
12. Menstrual Cycle – Simplified Diagram
13. Menstruation | मासिक धर्म
Menstruation is the shedding of the thickened uterine lining when fertilisation has not occurred.
Menstrual flow passes out through the vagina.
The first menstrual period is called menarche.
हिन्दी:
जब निषेचन नहीं होता है, तब गर्भाशय की मोटी आंतरिक परत टूटकर बाहर निकलती है। इसे मासिक धर्म कहते हैं। पहली बार होने वाले मासिक धर्म को Menarche (रजोदर्शन) कहते हैं।
हिन्दी:
जब निषेचन नहीं होता है, तब गर्भाशय की मोटी आंतरिक परत टूटकर बाहर निकलती है। इसे मासिक धर्म कहते हैं। पहली बार होने वाले मासिक धर्म को Menarche (रजोदर्शन) कहते हैं।
14. Menarche | रजोदर्शन
Menarche is the first menstrual period, marking an important stage of reproductive maturity.
The age at menarche varies from person to person.
हिन्दी:
पहली बार होने वाला मासिक धर्म रजोदर्शन (Menarche) कहलाता है। इसका समय प्रत्येक व्यक्ति में अलग हो सकता है।
हिन्दी:
पहली बार होने वाला मासिक धर्म रजोदर्शन (Menarche) कहलाता है। इसका समय प्रत्येक व्यक्ति में अलग हो सकता है।
15. Menopause | रजोनिवृत्ति
Menopause is the natural stage when menstrual cycles permanently stop, marking the end of the reproductive phase.
It generally occurs later in adult life.
हिन्दी:
रजोनिवृत्ति वह प्राकृतिक अवस्था है जिसमें मासिक धर्म स्थायी रूप से बंद हो जाता है और प्रजनन अवस्था समाप्त हो जाती है।
हिन्दी:
रजोनिवृत्ति वह प्राकृतिक अवस्था है जिसमें मासिक धर्म स्थायी रूप से बंद हो जाता है और प्रजनन अवस्था समाप्त हो जाती है।
16. Follicular Phase | फॉलिक्युलर चरण
During the follicular phase, ovarian follicles grow and develop.
FSH plays an important role in follicular development.
Developing follicles produce increasing amounts of estrogen.
The uterine lining begins to rebuild and thicken.
17. Ovulation | अंडोत्सर्जन
Ovulation is the release of a mature ovum from an ovarian follicle.
In a typical 28-day cycle, ovulation occurs approximately around day 14, but the exact timing varies.
A rapid rise in LH, called the LH surge, triggers ovulation.
हिन्दी:
अंडाशय के परिपक्व फॉलिकल से अंडाणु का बाहर निकलना अंडोत्सर्जन कहलाता है। सामान्य 28-दिवसीय चक्र में यह लगभग 14वें दिन के आसपास हो सकता है, लेकिन वास्तविक समय अलग हो सकता है। LH में अचानक वृद्धि, जिसे LH surge कहते हैं, अंडोत्सर्जन को प्रेरित करती है।
हिन्दी:
अंडाशय के परिपक्व फॉलिकल से अंडाणु का बाहर निकलना अंडोत्सर्जन कहलाता है। सामान्य 28-दिवसीय चक्र में यह लगभग 14वें दिन के आसपास हो सकता है, लेकिन वास्तविक समय अलग हो सकता है। LH में अचानक वृद्धि, जिसे LH surge कहते हैं, अंडोत्सर्जन को प्रेरित करती है।
18. Luteal Phase | ल्यूटियल चरण
After ovulation, the ruptured follicle forms the corpus luteum.
It secretes progesterone and also some estrogen.
Progesterone helps maintain the uterine lining for possible implantation.
19. If Fertilisation Does Not Occur | यदि निषेचन नहीं होता
Ovulation
→
No Fertilisation
→
Corpus Luteum Degenerates
→
Hormone Levels Fall
→
Uterine Lining Sheds
→
Menstruation
20. If Fertilisation Occurs | यदि निषेचन होता है
Ovulation
→
Fertilisation
→
Zygote
→
Embryo
→
Implantation
→
Pregnancy
21. Important Hormones | महत्वपूर्ण हार्मोन
| Hormone | Source | Main Role |
|---|---|---|
| GnRH | Hypothalamus | Stimulates pituitary release of FSH and LH. |
| FSH | Pituitary gland | Promotes growth and maturation of ovarian follicles. |
| LH | Pituitary gland | LH surge triggers ovulation; supports corpus luteum formation. |
| Estrogen | Developing ovarian follicles | Helps reproductive development and rebuilding of uterine lining. |
| Progesterone | Corpus luteum | Helps maintain uterine lining after ovulation. |
22. Menstrual Cycle at a Glance | एक नजर में मासिक चक्र
| Stage | Main Event |
|---|---|
| Menstruation | Shedding of uterine lining. |
| Follicular Phase | Follicle development and rising estrogen. |
| Ovulation | Release of mature ovum. |
| Luteal Phase | Corpus luteum produces progesterone. |
| If no fertilisation | Hormone levels fall and menstruation begins. |
| If fertilisation occurs | Embryo implants and pregnancy develops. |
23. Puberty vs Menstruation | यौवनारंभ और मासिक धर्म
| Puberty | Menstruation |
|---|---|
| A stage of physical and reproductive maturation. | A cyclic shedding of uterine lining. |
| Occurs over a period of development. | Occurs cyclically after menarche during reproductive years. |
| Includes many physical and hormonal changes. | Is one event within the menstrual cycle. |
24. Menarche vs Menopause
| Menarche | Menopause |
|---|---|
| First menstrual period. | Permanent stopping of menstrual cycles. |
| Marks the beginning of reproductive maturity. | Marks the end of reproductive phase. |
25. Gametes and Sex Chromosomes | युग्मक और लैंगिक गुणसूत्र
The human ovum normally carries an X chromosome.
Sperm may carry either X or Y.
Therefore:
| Sperm | Ovum | Zygote |
|---|---|---|
| X | X | XX |
| Y | X | XY |
Important:
The mother contributes an X chromosome through the ovum, while the sperm contributes either X or Y. Thus, the sperm's sex chromosome determines whether the zygote is XX or XY.
The mother contributes an X chromosome through the ovum, while the sperm contributes either X or Y. Thus, the sperm's sex chromosome determines whether the zygote is XX or XY.
26. Animated Menstrual Cycle Flow
27. 30 MCQs – CBSE + Foundation + Competitive
Q1. Puberty is mainly associated with:
A) Reproductive maturation
B) Digestion only
C) Respiration only
D) Excretion only
Answer: A) Reproductive maturation
Q2. The male gamete is:
A) Ovum
B) Sperm
C) Zygote
D) Embryo
Answer: B) Sperm
Q3. The female gamete is:
A) Sperm
B) Zygote
C) Ovum
D) Embryo
Answer: C) Ovum
Q4. Human gametes normally contain:
A) 46 chromosomes
B) 44 chromosomes
C) 92 chromosomes
D) 23 chromosomes
Answer: D) 23 chromosomes
Q5. The first menstrual period is called:
A) Menarche
B) Menopause
C) Ovulation
D) Fertilisation
Answer: A) Menarche
Q6. Permanent cessation of menstrual cycles is called:
A) Menarche
B) Menopause
C) Ovulation
D) Implantation
Answer: B) Menopause
Q7. Which hormone surge triggers ovulation?
A) FSH
B) Estrogen
C) LH
D) Progesterone
Answer: C) LH
Q8. Which hormone helps maintain the uterine lining after ovulation?
A) LH
B) FSH
C) GnRH
D) Progesterone
Answer: D) Progesterone
Q9. Ovulation is:
A) Release of a mature ovum
B) Fusion of gametes
C) Implantation
D) Menstruation
Answer: A) Release of a mature ovum
Q10. FSH is secreted by the:
A) Ovary
B) Pituitary gland
C) Uterus
D) Thyroid
Answer: B) Pituitary gland
Q11. The corpus luteum forms after:
A) Menstruation
B) Fertilisation
C) Ovulation
D) Menopause
Answer: C) Ovulation
Q12. Menstruation occurs when:
A) Sperm is produced
B) Fertilisation always occurs
C) Implantation occurs
D) The uterine lining is shed
Answer: D) The uterine lining is shed
Q13. A human zygote normally contains:
A) 46 chromosomes
B) 23 chromosomes
C) 22 chromosomes
D) 92 chromosomes
Answer: A) 46 chromosomes
Q14. Which chromosome is normally present in every human ovum?
A) Y
B) X
C) Both X and Y
D) Neither
Answer: B) X
Q15. Which hormone promotes ovarian follicle development?
A) Progesterone
B) LH only
C) FSH
D) Testosterone
Answer: C) FSH
Q16. Which phase follows ovulation?
A) Menstrual phase
B) Follicular phase
C) Menarche
D) Luteal phase
Answer: D) Luteal phase
Q17. The corpus luteum mainly secretes:
A) Progesterone
B) Insulin
C) Thyroxine
D) Adrenaline
Answer: A) Progesterone
Q18. Which hormone is mainly produced by developing ovarian follicles?
A) Testosterone
B) Estrogen
C) Insulin
D) ADH
Answer: B) Estrogen
Q19. The typical textbook menstrual cycle is often described as:
A) 7 days
B) 14 days
C) 28 days
D) 60 days
Answer: C) 28 days
Q20. Which statement about the menstrual cycle is correct?
A) Every person's cycle is exactly 28 days.
B) Ovulation always occurs on day 10.
C) Menstruation means fertilisation has occurred.
D) Cycle length can vary between individuals.
Answer: D) Cycle length can vary between individuals.
Q21. Menarche refers to:
A) First menstruation
B) Last menstruation
C) Ovulation
D) Fertilisation
Answer: A) First menstruation
Q22. Which hormone is released by the hypothalamus to regulate pituitary gonadotropins?
A) FSH
B) GnRH
C) Estrogen
D) Progesterone
Answer: B) GnRH
Q23. If fertilisation does not occur, the corpus luteum generally:
A) Grows indefinitely
B) Produces sperm
C) Degenerates
D) Becomes the uterus
Answer: C) Degenerates
Q24. Which structure is shed during menstruation?
A) Ovary
B) Fallopian tube
C) Cervix
D) Uterine lining
Answer: D) Uterine lining
Q25. Which is a secondary sexual characteristic in girls?
A) Breast development
B) Sperm formation
C) Prostate development only
D) Voice box only
Answer: A) Breast development
Q26. Which is a secondary sexual characteristic commonly seen in boys?
A) Menstruation
B) Facial hair growth
C) Ovulation
D) Breastfeeding
Answer: B) Facial hair growth
Q27. Which sequence is correct?
A) Menstruation → Ovulation → Follicular → Luteal
B) Luteal → Ovulation → Menstruation → Follicular
C) Follicular → Ovulation → Luteal → Menstruation
D) Ovulation → Menstruation → Luteal → Follicular
Answer: C) Follicular → Ovulation → Luteal → Menstruation
Q28. What happens to the chromosome number after fertilisation?
A) It becomes zero.
B) It remains 23.
C) It becomes 92.
D) It is restored to the diploid number of 46.
Answer: D) It is restored to the diploid number of 46.
Q29. Which event is directly triggered by the LH surge?
A) Ovulation
B) Menopause
C) Menarche
D) Menstruation
Answer: A) Ovulation
Q30. Which statement is correct?
A) Ovum contains 46 chromosomes.
B) Sperm contains 23 chromosomes.
C) Zygote contains 23 chromosomes.
D) All gametes are diploid.
Answer: B) Sperm contains 23 chromosomes.
28. 30 Subjective Questions with Answers
2 Marks
Q1. What is puberty?
Answer: Puberty is the stage when reproductive organs mature and secondary sexual characteristics develop.
2 Marks
Q2. What are gametes?
Gametes are specialised reproductive cells involved in sexual reproduction. Human male gamete is sperm and female gamete is ovum.
2 Marks
Q3. What is menarche?
Menarche is the first menstrual period in a female.
2 Marks
Q4. What is menopause?
Menopause is the natural permanent cessation of menstrual cycles, marking the end of the reproductive phase.
2 Marks
Q5. What is ovulation?
Ovulation is the release of a mature ovum from an ovarian follicle.
3 Marks
Q6. Write three changes that occur during puberty in girls.
- Development of breasts.
- Growth of pubic and underarm hair.
- Beginning of menstrual cycles and maturation of reproductive organs.
3 Marks
Q7. Write three changes that occur during puberty in boys.
- Growth of facial and body hair.
- Voice generally becomes deeper.
- Testes mature and sperm production begins.
3 Marks
Q8. What are the functions of FSH and LH?
FSH promotes ovarian follicle development. LH contributes to ovulation and formation/support of the corpus luteum.
3 Marks
Q9. What is the chromosome number in human sperm and ovum?
Both sperm and ovum normally contain 23 chromosomes and are haploid.
3 Marks
Q10. Why are gametes haploid?
Gametes contain one set of chromosomes so that fusion of two gametes restores the diploid chromosome number in the zygote.
4 Marks
Q11. Explain puberty and its major changes.
Puberty is the stage of reproductive maturation. During puberty, reproductive organs mature, gamete production begins, hormone levels change and secondary sexual characteristics develop. Physical growth and emotional changes also occur.
4 Marks
Q12. Explain the importance of gametes in sexual reproduction.
Gametes carry genetic information from parents. Sperm and ovum fuse during fertilisation to form a zygote. Since each gamete is haploid, their fusion restores the diploid chromosome number.
4 Marks
Q13. Define menstruation and explain why it occurs.
Menstruation is the shedding of the uterine lining. It occurs when fertilisation does not occur and hormonal support for maintaining the uterine lining decreases.
4 Marks
Q14. What is the role of estrogen in the menstrual cycle?
Estrogen is produced mainly by developing ovarian follicles. It supports reproductive development and helps rebuild and thicken the uterine lining during the follicular phase.
4 Marks
Q15. What is the role of progesterone?
Progesterone is mainly secreted by the corpus luteum after ovulation. It helps maintain the uterine lining and prepares it for possible implantation.
5 Marks
Q16. Explain the menstrual cycle in sequence.
The cycle begins with menstruation. During the follicular phase, follicles develop and estrogen rises. Around the middle of a typical cycle, an LH surge triggers ovulation. After ovulation, the corpus luteum develops and secretes progesterone. If fertilisation does not occur, hormone levels fall and menstruation begins again.
5 Marks
Q17. Explain the role of FSH and LH in the female reproductive cycle.
FSH promotes growth and maturation of ovarian follicles. Developing follicles produce estrogen. LH rises sharply around the middle of the cycle and its surge triggers ovulation. After ovulation, LH supports the corpus luteum.
5 Marks
Q18. Explain the significance of the corpus luteum.
After ovulation, the ruptured follicle becomes the corpus luteum. It secretes progesterone, which helps maintain the uterine lining. If pregnancy does not occur, the corpus luteum degenerates and hormone levels fall.
5 Marks
Q19. Differentiate between menarche and menopause.
Menarche is the first menstrual period and marks an important stage of reproductive maturity. Menopause is the natural permanent stopping of menstrual cycles and marks the end of the reproductive phase.
5 Marks
Q20. Explain why menstruation occurs when fertilisation does not take place.
If fertilisation does not occur, pregnancy does not begin. The corpus luteum degenerates, progesterone and other hormonal support decrease, and the thickened uterine lining breaks down and is shed as menstrual flow.
6 Marks
Q21. Explain puberty in detail.
Puberty is the period during which reproductive organs become mature and the body develops reproductive capability. It involves hormonal changes, maturation of gonads, beginning of gamete production, development of secondary sexual characteristics, rapid physical growth and emotional changes. In girls, breast development and menstruation occur; in boys, facial hair growth, voice change and sperm production develop.
6 Marks
Q22. Explain the menstrual cycle with its major stages.
The menstrual cycle includes menstruation, follicular development, ovulation and the luteal phase. During the follicular phase, follicles develop and estrogen rises. LH surge causes ovulation. The corpus luteum forms after ovulation and secretes progesterone. If fertilisation does not occur, the corpus luteum degenerates, hormone levels fall and menstruation begins.
6 Marks
Q23. Explain how hormones control the menstrual cycle.
The hypothalamus releases GnRH, which stimulates the pituitary to release FSH and LH. FSH promotes follicle development. Follicles produce estrogen. A high estrogen level contributes to the LH surge, causing ovulation. The corpus luteum then produces progesterone, which maintains the uterine lining.
6 Marks
Q24. Explain the significance of haploid gametes.
Human gametes contain 23 chromosomes instead of 46. During fertilisation, sperm and ovum fuse and their chromosome sets combine. This produces a zygote with 46 chromosomes. Haploid gametes therefore help maintain the chromosome number from one generation to the next.
6 Marks
Q25. Explain the relationship between ovulation, fertilisation and menstruation.
Ovulation releases a mature ovum. If sperm meets the ovum, fertilisation may occur in the fallopian tube. The resulting embryo can implant in the uterus. If fertilisation does not occur, the corpus luteum degenerates, hormone levels fall and the uterine lining is shed during menstruation.
6 Marks
Q26. Explain the role of estrogen and progesterone during the menstrual cycle.
Estrogen produced mainly by developing follicles helps the uterine lining rebuild and thicken. After ovulation, progesterone secreted by the corpus luteum helps maintain the uterine lining. If pregnancy does not occur, hormone levels decline and menstruation begins.
6 Marks
Q27. Explain the difference between sperm and ovum.
| Sperm | Ovum |
|---|---|
| Male gamete. | Female gamete. |
| Small and motile. | Much larger and generally non-motile. |
| Can carry X or Y chromosome. | Normally carries X chromosome. |
| Produced in testes. | Produced/matured in ovaries. |
6 Marks
Q28. Explain what happens if fertilisation occurs and if it does not occur.
If fertilisation occurs: Sperm and ovum fuse to form a zygote. The zygote divides, forms an embryo and implants in the uterine lining.
If fertilisation does not occur: The corpus luteum degenerates, hormone levels decrease and the uterine lining is shed as menstruation.
If fertilisation does not occur: The corpus luteum degenerates, hormone levels decrease and the uterine lining is shed as menstruation.
6 Marks
Q29. Explain menarche and menopause and their significance.
Menarche is the first menstrual period and indicates that the reproductive system has reached an important stage of maturity. Menopause is the natural permanent cessation of menstrual cycles later in adult life and marks the end of the reproductive phase.
6 Marks
Q30. Explain the complete flow of events in a typical menstrual cycle.
Menstruation → Follicular development → Estrogen rise → LH surge → Ovulation → Corpus luteum formation → Progesterone secretion → If no fertilisation, corpus luteum degenerates → Hormone levels fall → Menstruation.
The exact duration and timing of these events can vary among individuals.
The exact duration and timing of these events can vary among individuals.
29. HOTS / Competency-Based Questions
HOTS 1: A student says that every menstrual cycle must be exactly 28 days. Is this correct?
Answer: No. 28 days is a commonly used textbook example. Menstrual cycle length varies among individuals and can vary from cycle to cycle.
HOTS 2: Why does the chromosome number not double in every generation?
Gametes are haploid and contain half the chromosome number. Their fusion during fertilisation restores the diploid number.
HOTS 3: Why is an LH surge important?
The LH surge triggers the release of a mature ovum from the ovarian follicle, i.e. ovulation.
HOTS 4: What would happen to the uterine lining if hormonal support falls after ovulation and pregnancy does not occur?
The uterine lining breaks down and is shed during menstruation.
HOTS 5: Why are gametes called haploid?
Because they contain only one set of chromosomes. In humans, each gamete normally contains 23 chromosomes.
30. Important Diagram Labelling
Ovary – अंडाशय
Fallopian Tube – फैलोपियन नलिका
Uterus – गर्भाशय
Endometrium – गर्भाशय की आंतरिक परत
Cervix – गर्भाशय ग्रीवा
Vagina – योनि
Ovum – अंडाणु
Corpus Luteum – कॉर्पस ल्यूटियम
31. CBSE Golden Points | परीक्षा के महत्वपूर्ण बिंदु
1 Puberty = reproductive maturation.
2 Sperm = male gamete.
3 Ovum = female gamete.
4 Human gametes contain 23 chromosomes.
5 Zygote normally contains 46 chromosomes.
6 Menarche = first menstruation.
7 Menopause = permanent cessation of menstrual cycles.
8 FSH supports follicle development.
9 LH surge triggers ovulation.
10 Ovulation = release of mature ovum.
11 Corpus luteum forms after ovulation.
12 Corpus luteum secretes progesterone.
13 Progesterone helps maintain uterine lining.
14 Fertilisation usually occurs in fallopian tube.
15 Implantation occurs in uterus.
32. Memory Trick | याद रखने की ट्रिक
F → O → L → M
F = Follicular Phase
O = Ovulation
L = Luteal Phase
M = Menstruation
Easy Cycle:
“Follicle → Ovulation → Luteal → Menstruation”
Hormone Trick:
FSH → Follicle
LH → Ovulation
Progesterone → Pregnancy-supporting uterine lining
F = Follicular Phase
O = Ovulation
L = Luteal Phase
M = Menstruation
Easy Cycle:
“Follicle → Ovulation → Luteal → Menstruation”
Hormone Trick:
FSH → Follicle
LH → Ovulation
Progesterone → Pregnancy-supporting uterine lining
33. One-Line Revision | एक पंक्ति में पूरा टॉपिक
Puberty → Gamete formation → Menstrual cycle → Ovulation → Fertilisation (if sperm meets ovum) → Implantation → Pregnancy
34. Final Summary | अंतिम सारांश
English:
Puberty is the period of reproductive maturation. During puberty, the reproductive organs become functional and secondary sexual characteristics develop. Human gametes are haploid and contain 23 chromosomes. The male gamete is sperm and the female gamete is ovum. In females, the menstrual cycle involves follicular development, ovulation, luteal activity and menstruation. FSH promotes follicle development, while the LH surge triggers ovulation. After ovulation, the corpus luteum secretes progesterone, which helps maintain the uterine lining. If fertilisation does not occur, hormonal support falls and menstruation begins. If fertilisation occurs, a zygote forms and may subsequently implant in the uterus.
हिन्दी:
यौवनारंभ प्रजनन परिपक्वता की अवस्था है। इस दौरान जनन अंग सक्रिय होते हैं और द्वितीयक लैंगिक लक्षण विकसित होते हैं। मानव युग्मक अगुणित होते हैं और इनमें 23 गुणसूत्र होते हैं। नर युग्मक शुक्राणु तथा मादा युग्मक अंडाणु है। महिलाओं में मासिक धर्म चक्र में फॉलिक्युलर विकास, अंडोत्सर्जन, ल्यूटियल चरण और मासिक धर्म शामिल होते हैं। FSH फॉलिकल के विकास में सहायता करता है जबकि LH surge अंडोत्सर्जन को प्रेरित करता है। अंडोत्सर्जन के बाद कॉर्पस ल्यूटियम प्रोजेस्टेरोन का स्राव करता है, जो गर्भाशय की आंतरिक परत को बनाए रखने में सहायता करता है। यदि निषेचन नहीं होता है तो हार्मोन का स्तर घटता है और मासिक धर्म शुरू हो जाता है। यदि निषेचन होता है तो युग्मनज बनता है और आगे चलकर गर्भाशय में आरोपण हो सकता है।
Puberty is the period of reproductive maturation. During puberty, the reproductive organs become functional and secondary sexual characteristics develop. Human gametes are haploid and contain 23 chromosomes. The male gamete is sperm and the female gamete is ovum. In females, the menstrual cycle involves follicular development, ovulation, luteal activity and menstruation. FSH promotes follicle development, while the LH surge triggers ovulation. After ovulation, the corpus luteum secretes progesterone, which helps maintain the uterine lining. If fertilisation does not occur, hormonal support falls and menstruation begins. If fertilisation occurs, a zygote forms and may subsequently implant in the uterus.
हिन्दी:
यौवनारंभ प्रजनन परिपक्वता की अवस्था है। इस दौरान जनन अंग सक्रिय होते हैं और द्वितीयक लैंगिक लक्षण विकसित होते हैं। मानव युग्मक अगुणित होते हैं और इनमें 23 गुणसूत्र होते हैं। नर युग्मक शुक्राणु तथा मादा युग्मक अंडाणु है। महिलाओं में मासिक धर्म चक्र में फॉलिक्युलर विकास, अंडोत्सर्जन, ल्यूटियल चरण और मासिक धर्म शामिल होते हैं। FSH फॉलिकल के विकास में सहायता करता है जबकि LH surge अंडोत्सर्जन को प्रेरित करता है। अंडोत्सर्जन के बाद कॉर्पस ल्यूटियम प्रोजेस्टेरोन का स्राव करता है, जो गर्भाशय की आंतरिक परत को बनाए रखने में सहायता करता है। यदि निषेचन नहीं होता है तो हार्मोन का स्तर घटता है और मासिक धर्म शुरू हो जाता है। यदि निषेचन होता है तो युग्मनज बनता है और आगे चलकर गर्भाशय में आरोपण हो सकता है।
Class 10 Science | How Do Organisms Reproduce?
Puberty, Gametes and Menstrual Cycle
CBSE • Foundation • Competitive Exam Preparation
Puberty, Gametes and Menstrual Cycle
CBSE • Foundation • Competitive Exam Preparation
