NCERT Solutions explain each process in a simple, step-by-step way, helping students clearly understand topics like gametogenesis, menstrual cycle, and fertilisation so they can write accurate answers in exams.
Since the solutions focus on using correct biological terms, clear definitions, and structured answers, they do help improve answer presentation in exams.
They can be helpful as they show how to structure answers with headings, keywords, and diagrams, which helps in scoring good marks in medium and long-answer questions.
The NCERT Solutions guide you on proper labelling, neat drawing, and writing short explanations along with diagrams, hence, helping you improve answer diagram based questions.
NCERT Solutions explain that spermatogenesis is the process of formation and development of sperm from male germ cells in the seminiferous tubules of the testes.
NCERT Solutions explain that oogenesis is the process of formation and development of the female gamete, or ovum, in the ovaries.
NCERT Solutions explain that after fertilisation, the zygote undergoes cell division, forms an embryo, gets implanted in the uterus, and develops into a foetus during pregnancy.
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NCERT Solutions Class 12 Biology Chapter 2 Human Reproduction
Chapter 2, Human Reproduction, from Class 12 biology teaches about how the human body produces gametes, supports fertilisation and development of a baby. This chapter clearly explains the structure and functions of the male and female reproductive systems, the process involved in the formation of gametes, menstrual cycle, fertilisation, and stages of embryonic development.
ALLEN provides complete solutions for biology that is interesting and easy to understand. Our goal is to help you see each step of development using clear language and quality diagrams. These solutions don’t just present the facts, they teach you the “how” and “why” of human biology. Opting for ALLEN’s resources provides you a clear, expert-verified perspective that makes your study process easier and enhances your confidence for the CBSE finals and NEET Exams.
1.0Key Concepts of Class 12 Biology Chapter 2 Human Reproduction
Human reproduction involves a series of biological processes, from the formation of gametes to fertilisation, pregnancy, childbirth, and lactation. This chapter covers the following concepts in detail:
Male Reproductive System: Learn about the structure and functions of the testes, reproductive ducts, accessory glands, and other important organs.
Female Reproductive System: Understand the structure and functions of the ovaries, oviducts, uterus, and other parts of the female reproductive system.
Gametogenesis: Study the formation of male and female gametes through spermatogenesis and oogenesis.
Menstrual Cycle: Understand the different phases of the menstrual cycle and the role of hormones in regulating these changes.
Fertilisation and Implantation: Learn how the sperm and ovum fuse during fertilisation and how the developing embryo becomes implanted in the uterine wall.
Embryonic Development: Understand the major stages of development from the zygote through embryo formation and development into a foetus.
Lactation: Learn how hormones regulate milk production after childbirth and understand the importance of lactation in newborn nutrition.
2.0NCERT Class 12 Biology Chapter 2 Human Reproduction : Detailed Solutions
Fill in the blanks :
(a) Humans reproduce ____.
(asexually/sexually)
Ans. Sexually
(b) Humans are -------------------.
(oviparous, viviparous, ovoviviparous)
Ans. Viviparous
(c) Fertilisation is------------------in humans.
(external/internal)
Ans. Internal
(d) Male and female gametes are--------.
(diploid/haploid)
Ans. Haploid
(e) Zygote is--------------------------.
(diploid/haploid).
Ans. Diploid
(f) The process of release of ovum from a mature
follicle is called ----------------------.
Ans. Ovulation
(g) Ovulation is induced by a hormone called
--------------------------.
Ans. Luteinising hormone (LH)
(h) The fusion of male and female gametes is called ---
-----------------------.
Ans. Fertilisation
(i) Fertilisation takes place in --------------------.
Ans. Ampulla of the oviduct
(j) Zygote divides to form ------------------------- which is implanted in uterus.
Ans. Blastocyst
(k) The structure which provides vascular connection between foetus and uterus is called --------------------------.
Ans. Placenta
Draw a labelled diagram of male reproductive system.
Ans.
Draw a labelled diagram of female reproductive system.
Ans.
Write two major functions each of testis and ovary.
Ans. (1) Functions of the Testis :
They produce male gametes (sperm) by the process of called spermatogenesis.
The leydig cells of the testis secrete the male sex hormone called testosterone.
(2) Functions of the ovary :
They produce female gametes (ovum) by the process of oogenesis.
The growing Graafian follicles secrete the female sex hormone called estrogen.
Describe the structure of a seminiferous tubule. [IMP.]
Ans.
A seminiferous tubule is made up of layer of male germ cells and large Sertoli cells (nurse cell).
The male germ cells undergo spermatogenesis to produce spermatocytes, spermatids and sperms.
The regions outside the seminiferous tubules called interstitial spaces have connective tissue which included blood vessels and leydig cell.
Leydig cells synthesise and secrete the male sex hormones called androgens, of which testosterone is the principle one.
What is spermatogenesis? Briefly describe the process of spermatogenesis.
Ans. It is the process of formation of haploid sperms in seminiferous tubules of testes.
Name the hormones involves in regulation of spermatogenesis.
Ans. GnRH (Gonadotropin releasing hormone), LH (Luteinising hormone), FSH (Follicle stimulating hormone) and androgens.
Define spermiogenesis and spermiation.
Ans. (1) Spermiogenesis :
The process of transformation of spermatids into spermatozoa in seminiferous tubules, is called spermiogenesis.
(2) Spermiation :
Sperm are finally released from the seminiferous tubules by the process called spermiation.
Draw a labelled diagram of sperm. [IMP.]
Ans.
What are the major components of seminal plasma?
Ans. The major components of seminal plasma are Secretions of the accessory sex glands of males - prostate gland, seminal vesicles, bulbourethral glands.
Mainly components of - calcium, fructose, and other enzymes
What are the major functions of male accessory ducts and glands?
Ans. The major functions of the male accessory ducts and glands are as follows:
Male accessory ducts
(a) Rete testis : Stores sperms that are produced by seminiferous tubules.
(b) Vasa efferentia : Conducts sperms from the rete testis to the epididymis.
(c) Epididymis : Physiological maturation of sperms, storage and nourishment.
(d) Vas deferens : Conducts sperms from epididymis to the urethra.
Male accessory glands
(a) Seminal vesicles : Activates and provides energy to facilitate sperm motility after ejaculation.
(b) Prostate gland : Nourishes and activates sperms, enhances sperm motility.
(c) Cowper's gland : It enhances mobility & survival potentiality of sperms in the genital tract of female reproductive system and neutralizes the activity of acidic female vaginal secretions.
What is oogenesis? give a brief account of oogenesis. [IMP.]
Ans. The process of formation of a mature female gamete is called Oogenesis. Oogenesis can be explain through following flow chart.
Draw a labelled diagram of a section through ovary.
Ans.The diagram of a section of an ovary is as follows -
Draw a labelled diagram of a Graafian follicle.
Ans. The diagram of a Graafian follicle is as follows :
Name the functions of the following :
(a) Corpus luteum
(b) Endometrium
(c) Acrosome
(d) Sperm tail
(e) Fimbriae
Ans. The functions of each are as follows :
(a) Corpus luteum - The corpus luteum secretes the hormone progesterone during the luteal phase of the menstrual cycle.
(b) Endometrium -The endometrium is the innermost layer of the uterus comprising of glands that undergoes cyclic changes during different stages of the menstrual cycle in order to prepare itself for the embryo-implantation process.
(c) Acrosome - It consists of the sperm lysin enzyme that helps in penetration of the outer membrane of the egg by sperm which facilitates the sperm to perforate through the egg during fertilization.
(d) Sperm tail - The sperm tail makes up for the longest part of the sperm, enabling the movement of the sperm, once it has entered the female reproductive tract.
(e) Fimbriae - The edges of the infundibulum process finger-like projections, which help in collection of the ovum after ovulation.
Identify True/False statements. Correct each false statement to make it true.
(a) Androgens are produced by Sertoli cells.
(True/False)
Ans. False, Correct statement : Androgens are produced by the Leydig cells.
(b) Spermatozoa get nutrition from Sertoli cells.
(True/False)
Ans. True
(c) Leydig cells are found in ovary. (True/False)
Ans. False, Correct statement : Leydig cells are found in testes.
(d) Leydig cells synthesise androgens.
(True/False)
Ans. True
(e) Oogenesis takes place in corpus luteum.
(True/False)
Ans. False, Correct statement : Oogenesis takes place in ovary.
(f) Menstrual cycle ceases during pregnancy.
(True/False)
Ans. True
(g) Presence or absence of hymen is not a reliable indicator of virginity or sexual experience.
(True/False)
Ans. True
What is menstrual cycle ?
Which hormones regulate menstrual cycle?
Ans. It is a reproductive cycle in the female primates (e.g. monkeys, apes and human beings), in females menstruation is repeated at an average interval of about 28/29 days, the cycle of events starting from one menstruation till the next one is called the menstrual cycle.
The different hormones that regulate the menstrual cycle are LH - Luteinising hormone,
FSH - Follicle stimulating hormone, progesterone, estrogen.
What is parturition? Which hormones are involved in induction of parturition?
Ans. Parturition is the process wherein a fully developed foetus from the mother's womb is expelled out after the completion of the gestation period. The two critical hormones are involved in the induction of parturition are
Oxytocin - It directs the full-term foetus towards the birth canal, as it causes the contraction of the smooth muscles of the myometrium of the uterus leading the baby to be expelled out.
Relaxin - It relaxes the pelvic ligaments, widening the pelvis to assist in an easier child birth.
In our society the women are often blamed for giving birth to daughters. Can you explain why this is not correct? [IMP.]
Ans. This is not correct to blame women for giving birth to daughter.
The male sperm contain either X or Y chromosome whereas the female egg contain only X chromosome.
At the time of fertilization, sperm with Y chromosome combine with egg containing X chromosome formed which would be male.
Thus scientifically sex of the baby is determined by the father and not by the mother as blamed in our society.
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?
Ans. Typically in a month, human ovaries release only one egg, rarely two. In case of identical twins or monozygotic twins one egg is released by the ovary which splits into two post fertilization. This is why identical twins exhibit the same genetic features.
On the other hand in fraternal twins or dizygotic twins, two eggs are released which are fertilized by two different sperms causing the fraternal twins to exhibit different genetic characters.
How many eggs do you think were released by the ovary of a female dog which gave birth to 6 puppies?
Ans. In order to have given birth to six puppies, the ovary of the female dog released six eggs. Hence, six zygotes were formed for each to develop into a puppy.
3.0NCERT Solutions for Class 12 Biology | Other Chapter-wise Links
Explore the chapter-wise NCERT Solutions for Class 12 Biology for all remaining chapters using the links below.
4.0Key Features and Benefits of Class 12 Biology Chapter 2 Human Reproduction
Clear Understanding of Reproductive Structures: Learn about the male and female reproductive systems, their main parts, and their functions with simple explanations.
NCERT-Based Solutions: Get clear solutions to NCERT textbook questions based on the concepts covered in Class 12 Biology Chapter 2.
Better Revision: Revise important terms, reproductive processes, and key concepts regularly to improve understanding and recall.
Strong Biology Fundamentals: Build a strong foundation in human reproduction for CBSE Board exams, NEET, and higher studies in biology.
Easy Understanding of Human Reproduction: Connect concepts such as gametogenesis, menstrual cycle, fertilisation, pregnancy, and reproductive health with human development and health.
Table of Contents
1.0Key Concepts of Class 12 Biology Chapter 2 Human Reproduction
2.0NCERT Class 12 Biology Chapter 2 Human Reproduction : Detailed Solutions
3.0NCERT Solutions for Class 12 Biology | Other Chapter-wise Links
4.0Key Features and Benefits of Class 12 Biology Chapter 2 Human Reproduction
