NCERT Solutions for Class 12 Chapter 2 Human Reproduction (original) (raw)

Last Updated : 23 Jul, 2025

**As per the revised curriculum of CBSE Syllabus 2023-24, this chapter, previously known as Chapter 3, has now been renumbered as Chapter 2. Stay updated with the latest changes in the curriculum.

**NCERT Solutions for Class 12 Chapter 2 Human Reproduction is all about the process of sexual reproduction among humans. This chapter of Class 12 talks about the female reproductive system and the male reproductive system in detail. The NCERT Solutions for this chapter are prepared by our Top Biology Experts to take care of all important topics that might be asked in the upcoming CBSE Class 12 Board examination 2024. So, students can also refer to these solutions for their final examination preparation.

This **Class 12 Biology Chapter 2 Human Reproduction NCERT Solutions are carefully developed using easy-to-understand language while adhering to the guidelines for solving NCERT Solutions for Class 12. Working through these solutions can be highly beneficial for students in their board exams, as well as in preparing for future competitive Exams.

Important Topics in Class 12 Biology Chapter 2 Human Reproduction

The chapter on human reproduction is vast and contain many unmissable topics. These most important topics are given below:

NCERT Solutions for Class 12 Biology Chapter 2 - Human Reproduction Questions and Answers

**Human reproduction class 12 NCERT solutions explains the ability of humans to produce offspring and carry out the next generation. As we all know, human reproduction is a sexual process that requires internal fertilization during sexual activity. Revise the basic concepts of NCERT Class 12 chapter on Human Reproduction for quick revision and class notes.

**Q1: Fill in the Blanks

• (a) Humans reproduce————— (asexually/sexually).
• (b) Humans are————— (oviparous, viviparous, ovoviviparous).
• (c) Fertilization is————— in humans (external/internal).
• (d) Male and female gametes are—————(diploid/haploid).
• (e) Zygote is————— (diploid/haploid).
• (f) The process of release of ovum from a mature follicle is called—————.
• (g) Ovulation is induced by a hormone called—————
• (h) The fusion of male and female gametes is called—————.
• (i) Fertilization takes place in—————
• (j) Zygote divides to form————— which is implanted in uterus.
• (k) The structure which provides a vascular connection between the fetus and uterus is called—————.

**Answer:

• (a) Sexually
• (b) Viviparous
• (c) Internal
• (d) Haploid
• (e) Diploid
• (f) Ovulation
• (g) LH (Luteinizing hormone)
• (h) Fertilization
• (i) Ampullary-isthmic junction (fallopian tube)
• (j) Blastocyst
• (k) Placenta (Umbilical cord)

**Q2: Draw a labeled diagram of the male reproductive system.

**Answer:

**For More Information Read: Diagram of Male Reproductive System

**Q3: Draw a labeled diagram of the female reproductive system.

**Answer:

**For More Information Read: Female Reproductive System

**Q4: Write two major functions for Each of the Testis and Ovary.

**Answer:

Functions of the Testis:

• They produce male gametes called spermatozoa by the process of spermatogenesis.
• The Leydig cells of the seminiferous tubules secrete the male sex hormone called testosterone. Testosterone aids the development of secondary sex characteristics in males.

Functions of the ovary:

• They produce female gametes called ova by the process of oogenesis.
• The growing Graffian follicles secrete the female sex hormone called estrogen. Estrogen aids the development of secondary sex characteristics in females.

**Q5: Describe the Structure of a Seminiferous Tubule.

**Answer:

The production of sperm in the testes takes place in a highly coiled structure called the seminiferous tubules. These tubules are located in the testicular lobules. Each seminiferous tubule is lined by germinal epithelium. It is lined on its inner side by two types of cells namely spermatogonia and Sertoli cells respectively. Spermatogonia are male germ cells that produce primary spermatocytes by meiotic divisions. Primary spermatocytes undergo further meiotic division to form secondary spermatocytes and finally, spermatids. Spermatids later metamorphose into male gametes called spermatozoa. Sertoli cells are known as nurse cells of the testes as they nourish the germ cells. There are large polygonal cells known as interstitial cells or Leydig cells just adjacent to seminiferous tubules. These cells secrete the male hormone called testosterone.

**For More Information Read: Seminiferous Tubule Diagram

**Q6: What is Spermatogenesis? Briefly Describe the Process of Spermatogenesis.

**Answer:

Spermatogenesis is the process of the production of sperms from immature germ cells in males. It takes place in seminiferous tubules present inside the testes. During spermatogenesis, a diploid spermatogonium (male germ cell) increases its size to form a diploid primary spermatocyte. This diploid primary spermatocyte undergoes the first meiotic division (meiosis I), which is a reductional division to form two equal haploid secondary spermatocytes. Each secondary spermatocyte then undergoes a second meiotic division (meiosis II) to form two equal haploid spermatids. Hence, a diploid spermatogonium produces four haploid spermatids. These spermatids are transformed into spermatozoa (sperm) by the process called spermiogenesis.

**For More Information Read: Spermatogenesis

**Q7: Name the Hormones involved in the Regulation of Spermatogenesis.

**Answer:

Follicle-stimulating hormones (FSH) and luteinizing hormones (LH) are secreted by gonadotropin-releasing hormones from the hypothalamus. These hormones are involved in the regulation of the process of spermatogenesis. FSH acts on Sertoli cells, whereas LH acts on Leydig cells of the testis and stimulates the process of spermatogenesis.

**Q8: Define Spermiogenesis and Spermiation.

**Answer:

**Spermiogenesis is the process of transformation of spermatids into mature flagellated spermatozoa (sperms). **Spermiation is the process of the release of mature spermatozoa. In this spermatozoa are shed into the lumen of the seminiferous tubule for transport.

**Also Read: Diagram of Spermatogenesis

**Q9: Draw a Labeled Diagram of Sperm.

**Answer:

**Also Read: Sperm Diagram

**Q10: What are the major components of Seminal Plasma?

**Answer:

Seminal plasma is the fluid in which sperm is ejaculated. Significant components of seminal plasma are secretions from seminal vesicles, prostate and bulbourethral gland, and sperms from the testis. It is rich in fructose and contains enzymes, citric acid, hormones like prostaglandins, calcium, and clotting proteins.

**Q11: What are the Major Functions of Male Accessory Ducts and Glands?

**Answer:

Male accessory ducts include rete testis, vasa efferentia, epididymis, and vas deferens. These ducts store and transport sperm from the testis to the outside through the urethra. The male accessory glands include paired seminal vesicles, a prostate, and paired bulbourethral glands. Secretions of these glands constitute the seminal plasma which is rich in fructose, calcium, and certain enzymes. The secretions of bulbourethral glands also help in the lubrication of the penis.

**Q12: What is Oogenesis? Give a Brief Account of Oogenesis.

**Answer:

The process of formation of a mature female gamete (ovum) is called oogenesis. It occurs in the ovaries of the female reproductive system. Oogenesis is a discontinuous process it begins before birth, stops in mid-process & only resumes after menarche. It occurs in three phases: Multiplicative phase (formation of oogonia mitotically from the primary germ cells), Growth phase (growth of oogonia into primary oocyte) & Maturation phase (formation of mature ova from primary oocyte through meiosis). The maturation phase produces two haploid cells – The larger one called the secondary oocyte & the smaller one called the polar body (1st polar body). Meiosis II of secondary oocyte results in the formation of a functional egg or ovum and a second polar body: The first polar body may also divide to form two polar bodies of equal sizes which do not take part in reproduction & ultimately degenerates. The first maturation division may be completed in the ovaries just before ovulation, but the second one (Final) is completed outside the ovary after fertilization. The secondary oocyte is a female gamete in which the 1st meiotic division is completed & second meiotic division (Metaphase stage) has begun. The egg is released at the secondary oocyte stage under the effect of LH.

**For More Information Read: What is Oogenesis?

**Q13: Draw a Labeled Diagram of a Section Through the Ovary.

**Answer:

**Also Read: Diagram of Ovary

**Q14: Draw a Labeled Diagram of a Graafian Follicle.

**Answer:

**Q15: Name the Functions of the Following:

• ****(a) Corpus luteum**
• ****(b) Endometrium**
• ****(c) Acrosome**
• ****(d) Sperm tail**
• ****(e) Fimbriae**

**Answer:

• (a) **Corpus luteum: The corpus luteum secretes large amounts of progesterone which are essential for the maintenance of the endometrium.
• (b) **Endometrium is necessary for implantation of the fertilized ovum and other events of pregnancy.
• (c) The **acrosome is filled with enzymes that help during fertilization of the ovum.
• (d) **Sperm tail: The tail facilitates sperm motility which is essential for fertilization.
• (e) **Fimbriae: Fimbriae help in the collection of the ovum after ovulation.

**Aso Read: Difference Between Corpus Callosum and Corpus Luteum

**Q16: Identify True/False Statements. Correct each False Statement to make it true.

• ****(a) Androgens are produced by Sertoli cells. (True/False)**
• ****(b) Spermatozoa get nutrition from Sertoli cells. (True/False)**
• ****(c) Leydig cells are found in the ovary. (True/ False)**
• ****(d) Leydig cells synthesize androgens. (True/ False)**
• ****(e) Oogenesis takes place in the corpus luteum. (True/False)**
• ****(i) Menstrual cycle ceases during pregnancy. (True/False)**
• ****(g) Presence or absence of a hymen is not a reliable indicator of virginity or sexual – experience. (True/False)**

**Answer:

• (a) False, Androgens or male sex hormones (e.g., testosterone) are secreted by Leydig cells.
• (b) True.
• (c) False, Leydig cells are found in the testis.
• (d) True.
• (e) False, Oogenesis takes place in the ovary.
• (f) True.
• (g) True.

**Q17: What is a Menstrual Cycle? Which Hormones Regulate the Menstrual cycle? Which Hormones Regulate the Menstrual Cycle?

**Answer:

Menstrual cycle is the cyclic change(of the reproductive tract of a primate female. This period is marked by a characteristic event repeated almost every month (28 days with minor variation) in the form of a menstrual flow (i.e. shedding of the endometrium of the uterus with bleeding. It may be temporarily stopped only during pregnancy.
The hormones that regulate menstrual cycles are

1. FSH (Follicle stimulating hormone),
2. LH (Luteinizing hormone),
3. Oestrogens,
4. Progesterone.

**For More Information Read: Menstrual Cycle

**Q18. What is Parturition? Which Hormones are involved in the Induction of Parturition?

**Answer:

Parturition (or labor) means childbirth. Parturition is the sequence of actions by which a baby and the afterbirth (placenta) are expelled from the uterus at childbirth. The process usually starts spontaneously about 280 days after conception, but it may be started by artificial means. The process of parturition is induced by a complex neuroendocrine mechanism involving cortisol, estrogen, and oxytocin.

**For More Information Read: Parturition

**Q19: In our Society, women are often blamed for giving birth to daughters. Can you explain why this is not correct?

**Answer:

The sex chromosome pattern in human females is XX and that of males is XY. Therefore, all the haploid female gametes (ova) have the sex chromosome X, however, the haploid male gametes have either X or Y. Thus 50% of sperms carry the X-chromosome while the other 50% carry the Y-chromosome. After the fusion of the male and female gametes, the zygote takes either XX or XY depending upon whether the sperm carrying X or Y fertilizes the ovum. The zygote carrying XX would be a female baby and XY would be a male baby. That is why it is correct to say that the sex of the baby is determined by the father.

**Q 20: How many Eggs are released by a Human Ovary in a month? How many eggs do you think would have been released if the mother gave birth to identical twins? Would your answer change if the twins born were fraternal?

**Answer:

One egg is released by the human ovary in a month. Identical twins: Identical twins are formed when a single fertilized egg splits into two genetically identical parts. The twins share the same DNA set, thus they may share many similar attributes. However, since physical appearance is influenced by environmental factors and not just genetics, identical twins can actually look very different. Fraternal twins: These twins are formed when two fertilized eggs are formed. The twins share different DNA sets, thus they may share different attributes (dizygotic embryos).

**Q21: How many eggs do you think were released by the Ovary of a Female Dog which gave Birth to 6 puppies?

**Answer:

Since dogs have multiple births, several eggs mature and are released at the same time. If fertilized, the egg will implant on the uterine wall. Dogs bear their litters roughly 9 weeks after fertilization, although the length of gestation can vary from 56 to 72 days. An average litter consists of about six puppies, though this number may vary widely based on the breed of dog. On this basis, 6 eggs were released by the ovary of a female dog which gave birth to 6 puppies.

Key Features of NCERT Solutions Class 12 Biology Chapter 2 Human Reproduction

• They enhance the conceptual knowledge of the students.
• Clear and Comprehensible Content.
• Help in Competitive Exam Preparation.
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