CBSE Class 12 Biology NCERT Exemplar Solutions: Chapter 3, Human ReproductionGurmeet Kaur
The NCERT Exemplar problems are considered to be the most applicative kind of problems which help to enhance a student’s critical thinking and problem solving ability. These problems are designed to increase the application skills of the students. The solutions to these problems can be arrived at only after a thorough understanding of the concepts involved in a subject.
Why to solve NCERT Exemplar Problems?
NCERT Exemplar problems are a very good resource for preparing the critical questions like Higher Order Thinking Skill (HOTS) questions. Every year, many questions from the NCERT Exemplar are directly asked in the board exams. Also, these are the kind of questions asked in the various competitive exams and Olympiad level tests. So, it’s very important for students to practice the NCERT exemplar problems to prepare well for the boards and the competitive exams.
NCERT Exemplar Solutions for Class 12 Biology Chapter - Human Reproduction:
In this article we are providing the precise solutions to all the NCERT Exemplar Problems for chapter Human Reproduction. All these solutions have been prepared by the subject matter experts. These solutions are designed in the most appropriate and the simplest way so as to help students easily understand the theories employed. This will help them make an easy preparation for the exams.
Few problems along with their solutions from this chapter are given follows:
Q. Spermiation is the process of the release of sperms from
(a) seminiferous tubules
(b) vas deferens
(d) prostate gland
Ans. (a) seminiferous tubules
The process of release of spermatozoa from Sertoli cells into the cavity of the seminiferous tubules is called spermiation. From here, sperms pass via vasa efferentia into the epididymis for temporary storage.
Q. From where the parturition signals arise: mother or foetus? Mention the main hormone involved in parturition.
Ans. Parturition is induced by a complex neuroendocrine mechanism. The signals for parturition originate from the fully developed foetus and the placenta which induce m Id uterine contractions called foetal ejection reflex.
The hormone involved in parturition is oxytocin that acts on the uterine muscle and causes stronger uterine contractions. This leads to the expulsion of the baby out of the uterus through the birth canal.
Q. A human female experiences two major changes, menarche and menopause during her life. Mention the significance of both the events.
Ans. In human beings, initiation of menstruation at puberty (between age 9-15 years) is called menarche. While, menstrual cycle ceases at around 50 years of age, which is termed as menopause. Menarche signifies the onset of puberty, i.e., beginning of reproductive phase in female.
Menopause signifies the end of reproductive phase in female. At this age supply of healthy eggs is very low, the levels of the hormones secreted by the ovaries decline and the menstruation stops. The uterus no longer remains conductive for foetal growth.
Q. The zygote passes through several developmental stages till implantation. Describe each stage briefly with suitable diagrams.
Ans. The zygote passes through the following stages till implantation:
(a) The zygote divides into two-cell stage called cleavage. This development takes place when the zygote is still in the isthmus.
(b) The cleavage undergoes further rounds of mitosis to form 2, 4, 8 and finally 16-celled stage. These daughter cells are called blastomere.
(c) The embryo with 8-16 blastomeres is called a morula.
(d) The morula continues to divide and transforms into blastocyst as it moves further into uterus.
(e) The blastomeres in the blastocyst are arranged into a surface layer called trophoblast and a cluster of interior cells attached to trophoblast are called the inner cell mass.
(f) The trophoblast layer then gets attached to the endometrium and inner mass cells get differentiated as embryo. (v) After attachment, the uterine cells divide rapidly to cover the blastocyst.
(g) The blastocyst becomes embedded in the uterine endometrium. This is called implantation.
Find below the links to download Class 12 Biology NCERT Exemplar Solutions for chapter 12- Human Reproduction:
Link to Download PDF
Multiple Choice Questions
Very Short answer type questions
Short answer type questions
Long answer types questions
About Class 12 Biology NCERT Exemplar Book:
NCERT Exemplar book for class 12 Biology consists of a collection of conceptual questions which are designed purely to check a student’s understanding about the various concepts and theories explained in the subject. These problems form the best practice source to prepare effectively for board exams and the medical entrance tests.
Here, we are providing the NCERT Exemplar Problems for Class 12 Biology chapter - Human Reproduction, in the PDF form which students may download and solve them to analyse their preparedness for the exams.
Note: Once you are done with all the NCERT Exemplar problems, refer the solutions given above in this article to check the correctness of your own solutions and know the right way to design perfect answers.
Main topics discussed in Class 12 Biology, Chapter 3- Human Reproduction, are:
- Male reproductive system
- Female reproductive system
- Menstrual cycle
- Fertilisation and implantation
- Pregnancy and embryonic development
- Parturition and lactation.
Download the complete NCERT Exemplar book from the following link:
Students having a good understating of the various terms and biological theories explained in the chapter: Human Reproduction, will be able to frame appropriate answers to the problems given NCERT exemplar book. After solving problems of NCERT exemplar problems one can easily identify his/her hold on the concepts and basics of the chapter.