Please refer to Human Reproduction Class 12 Biology Important Questions with answers below. These solved questions for Chapter 3 Human Reproduction in NCERT Book for Class 12 Biology have been prepared based on the latest syllabus and examination guidelines issued by CBSE, NCERT, and KVS. Students should learn these solved problems properly as these will help them to get better marks in your class tests and examinations. You will also be able to understand how to write answers properly. Revise these questions and answers regularly. We have provided Notes for Class 12 Biology for all chapters in your textbooks.

Important Questions Class 12 Biology Chapter 3 Human Reproduction

All Human Reproduction Class 12 Biology Important Questions provided below have been prepared by expert teachers of Standard 12 Biology. Please learn them and let us know if you have any questions.

Question. Name the structures which secrete estrogen.
Answer : Ovarian follicles

Question. Explain the stages of embryo development from fertilization to implantation.
Answer : Zygote – cleavage, blastomeres, morula, blastocyst, trophoblast, inner cell mass, attached to endometrium implantation, diiferentiate as embryo.

Question. Name the site of fertilization in human beings.
Answer : Ampullary-isthmic junction of fallopian tube

Question. Differentiate between Leydig cells and Sertoli cells with reference to their location in the organ and their function
Answer : Leydig–in interstitial space, form androgen, Sertoli– in seminiferoustubule, give nutrition to germ cells

Question. What is the main function of Sertoli cells?
Answer : Provide nutrition to germ cells

Question. What is parturition? How is it induced? Which hormones are involved in induction of parturition?
Answer : Delivery of foetus, foetal ejection reflex, oxytocin

Question. Name the outermost layer of the blastocyst.
Answer : Trophoblast

Question. How many spermatozoa will be produced from 100 primary spermatocytes and how many ova will be produced from 100 primary oocytes?
Answer : 400 spermatozoa, 100 eggs

Question. Name the cells which secrete androgens.
Answer : Leydig cells

Question. What is ovulation? What happens to Graafian follicle after ovulation?
Answer : The release of secondary oocyte from ovary, transforms into corpus luteum.

Question. What are the main features of embryonic development at various months of pregnancy?
Answer : One month- heart, end of second month – limbs and digits, end of 12 weeks –major organ system – limbs genital organs. fifth monthmovements, second trimester fine hair, eyelids separate eye lashes

Question. Is it correct to say that the sex of the child is determined by the woman and not by the man?
Answer : No.

Question. What is colostrum? What is its importance?
Answer : Milk produced during initial days of lactation, antibodies (IGA) to give resistance

Question. Mention any three differences between spermatogenesis and oogenesis.
Answer : At puberty / during embryonic development ;four sperms / one egg ; equal division / unequal division

Question. What does the head of a sperm consists of?
Answer : Haploid nucleus , acrosome

Question. Name the structure which secretes progesterone.
Answer : Corpus luteum

Question. What is seminiferous tubule? Name the various types of cells present in it and explain its function.
Answer : Highly coiled in testicular lobule, male germ cells, sertoli cells ; sperm formation, provide nutrition

Question. Explain different phases of spermatogenesis with schematic representation.
Answer : Spermatogonia – primary spermatocyte (meiosis I)– secondary spermatocyte (meiosis II) – spermatid – sperm

Question. Explain different phases of oogenesis with schematic representation
Answer : Oogonia- primary oocyte , primary –>secondary—> tertiary graafian follicles –> secondary oocyte –> ovum

Question. Name the three layers of embryo that give rise to all tissues and also name the cells which have the potency to give rise to all the tissues and organs.
Answer : Ectoderm, endoderm, mesoderm, stem cells

Question. What is oogenesis? Where does it occur?
Answer : Formation of mature female gamete, Ovary

Question. Explain the various phase of menstrual cycle with reference to changes in ovary and uterus and hormonal cycle.
Answer : Menstrual phase – flow ; follicular phase – follicular growth regeneration of endometrium ; Ovulation ; secretary phase – corpus luteum LH, FSH role

Question. Explain the process of fertilization.
Answer : Sperm comes in contact with zona pellucida, block entry of additional sperms, acrosome helps in entry, completion second meiotic division second polar body, ootid, haploid nucleus of sperm fuses with ovum

Question. What promotes completion of second meiotic division in oogenesis?
Answer : Entry of sperm into cytoplasm of the ovum through zona pellucida membrane and plasma

Question. Testes normally remain suspended in scrotum in mammals. Why?
Answer : Scrotum helps in maintaining low temperature , necessary for spermatogenesis

Question. Draw a diagrammatic presentation of various events during a menstrual cycle.
Answer : Schematic representation of menstrual cycle ovarian events, uterine events, hormones of pituitary, ovarian hormones

Question. Name the glands associated with male reproductive organs and state their functions.
Answer : Paired seminal vesicles, a prostate gland paired bulbourethral gland ; seminal plasma rich in fructose calcium enzymes, bulbourethral – lubrication of penis

Question. What is placenta? What is its role? Justify Placenta as an endocrine tissue.
Answer : Structural and functional unit between foetus and mother, supply of nutrients and oxygen removal of wastes secretes, hCG, hPL, estrogens, progestogens.