12th Standard CBSE Biology Human Reproduction Important Questions
12th Standard CBSE Biology Human Reproduction Important Questions
QB365 - Question Bank Software
Human Reproduction Important Questions
12th Standard CBSE
-
Reg.No. :
Biology
-
Write two major functions of testis and ovary each.
-
Define spermiogenesis and spermiation
-
What is parturition?Which hormones are involved in induction of parturition?
-
How many eggs do you think were released by the ovary of a female dog which gave birth to 6 puppies?
-
What is menstrual cycle? Which hormones regulate menstrual cycle?
-
Describe the structure of a seminiferous tubule.
-
What are the major components of the seminal plasma?
-
The secondary oocyte retains bulk of the nutrientrich cytoplasm ofthe primary oocyte. Can you think
or any advantage for this? -
How many chromosomes will be there in the zygote (of human)?
-
What do you think the doctor injects to induce delivery?
-
Describe how the changing levels of FSH,LH and progesterone during mentrual cycle induce changes in the ovary and the uterus in human female.
-
Name the hormones involved in the regulation of spermatogenesis.
-
What are the major fuctions of male accessory ducts and glands?
-
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?
-
Draw a labelled diagram of a section through ovary.
-
In our society the women are often blamed for giving birth to daughters. Can you explain why this is not correct?
-
Draw a labelled diagram of male reproductive system.
-
Draw a labelled diagram of female reproductive system.
-
Write two major functions each of testes and ovaries.
-
What is spermatogenesis? Briefly describe the process of spermatogenesis.
-
Draw a labelled diagram of a Graafian follicle?
-
Name the functions of the following:
(a) Corpus luteum
(b) Endometrium
(c) Acrosome
(d) Sperm tail
(e) Fimbriae -
A diagrammatic sketch of the human male reproductive system is given above.
(a) Identify and name the three glands associated with the human male reproductive system. What is the term given to their secretions?
(b) Name the primary sex organ and the pouch in which it is located in human beings. -
A Human Spermatozoan
A diagrammatic sketch of a human sperm is given. Identify the parts labelled A, Band C and mention their respective functions. -
Study the following flow chart and answer the questions that follow:
-
With reference to the above schematic diagram of (a) Spermatogenesis and (b) Oogenesis, answer the following questions.
(a) About 300 million spermatozoa may be present in a human male ejaculate at one time. Calculate how many primary spermatocytes will be involved to produce this number of spermatozoa .
(b) How many spermatids will be formed?
(c) How many chromatids are found during Oogenesis in
(i) Primary oocyte and
(ii) First polar body in a human female? -
(A) In the diagrammatic sectional view of a human ovary, identify the following:
(i) Corpus luteum
(ii) Antrum
(iii) Secondary oocyte
(iv) Primary follicle
(B) Name the hormone that
(i) influences the formation of corpus luteum.
(ii) is secreted by corpus luteum. -
The events in a menstrual cycle are represented above. Answer the following questions based on that.
(a) Why is the phase between 5th and 15th day of menstrual cycle, called
(i) proliferative phase?
(ii) follicular phase?
(b) Mention the ovarian events during the luteal phase. -
Read the graph given above and answer the following questions:
(a) Identify the ovarian hormones X and Y and name their respective sources in the ovary.
(b) Why does the hormone X peak before the hormone Y? -
(a) Identify the pituitary hormones 'X' and 'Y' shown in the graph.
(b) Mention two functions each of X and Y in human females. -
Study the flow chart given below and answer the questions that follow:
(a) Name the hormone(s) (in full form) involved in each of the stages,
(b) Specify the structure in the ovary that is the source of the hormone at stage
-
(a) Identify the human embryonic stages, A and B given.
(b) Write two differences between A and B. -
(a) Name the human embryonic stage shown above.
(b) Identify 'a' and 'b' in it.
(c) Where are stem cells located in it?
(d) Mention the role of 'b'. -
Three of the steps in the neuro-endocrine mechanism of parturition are mentioned below. Write the other missing steps.
(a) Signals for parturition originate from the fullydeveloped foetus and placenta.
(b) _________________.
(c) _________________.
(d) Oxytocin causes stronger uterine contractions, which stimulate further secretion of oxytocin.
(e) __________________.
(f) ________________. -
Read the following and answer any four questions from (i) to (v) given below:
Human male reproductive system comprises of a pair of testes, primary sex organs associated with formation of gametes and production of sex hormone. Study the given figure of human male reproductive system and answer the following questions.
(i) Which of the following is correct for labelled part P?(a) P is rete testis which transports sperms to outside. (b) P is epididymis which secretes fluid that nourish the sperms (c) P is epididymis that carry sperms and secretion of seminal vesicles (d) P is rete testis which lies along inner side of each testis and stores the sperms (ii) Identify the correctly matched pair.
(a) Q - Vasa efferentia (b) R - Ejaculatory duct (c) S - Seminal vesicle (d) T - Cowper's gland (iii) Which statement is incorrect for Q?
(a) It carries spermatozoa from epididymis to ejaculatory duct (b) Q are only 2 in number. (c) It arises from rete testis. (d) It constitutes male sex accessory duct (iv) Which structure passes through the prostate gland and carries sperms and secretion of seminal vesicle?
(a) P (b) T (c) S (d) R (v) Assertion: Mucus present in secretion of bulbourethral gland decreases the number of sperms damaged during ejaculation
Reason: Mucus lubricates the end of penis and lining of the urethra.
(a) Both assertion and reason are true and reason is the correct explanation of assertion.
(b) Both assertion and reason are true but reason is not the correct explanation of assertion.
(c) Assertion is true but reason is false.
(d) Both assertion and reason are false . -
Read the following and answer any four questions from (i) to (v) given below:
Oogenesis is the process of formation of ovum in ovaries. It consists of three phases : multiplication, growth and maturation. Oogenesis is controlled by hormones GnRH, LH, FSH. GnRH secreted by the hypothalamus stimulates the anterior lobe of pituitary gland to secrete LH and FSH.
(i) What is the function of hormone FSH?(a) It inhibits the formation of estrogen (b) It induces the release of secondary oocyte (c) It stimulates the growth of Graafian follicles (d) It causes ovulation. (ii) Which hormone induces the rupture of the mature Graafian follicle?
(a) Follicle stimulating hormone (b) Gonadotropin releasing hormone (c) Progesterone (d) Luteinising hormone (iii) Which cell division is involved in the formation of secondary oocyte?
(a) Mitosis (b) Meiosis I (c) Amitosis (d) Meiosis II (iv) Identify the function(s) of LH.
(A) Release of secondary oocyte from Graafian follicle.
(B) Stimulates corpus luteum to secrete progesterone.
(C) Stimulates estrogen formation.
(D) Promotes development of egg to form secondary oocyte.(a) (A) and (B) only (b) (B) and (C) only (c) (A), (C) and (D) only (d) (B) only (v) Assertion: The increase in progesterone level exerts positive feedback on GnRH
Reason: The rising level of progesterone stimulate production of FSH and LH.
(a) Both assertion and reason are true and reason is the correct explanation of assertion.
(b) Both assertion and reason are true but reason is not the correct explanation of assertion.
(c) Assertion is true but reason is false.
(d) Both assertion and reason are false. -
Read the following and answer any four questions from (i) to (v) given below:
The first menstruation is called menarche, that usually occurs between 12 and 15 years. In human females, menstruation is repeated at an average interval of about 28129 days and is called menstrual cycle. It is regulated by certain hormones, as pituitary gland is stimulated by releasing factors produced in the hypothalamus. The hormones produced by pituitary gland influence the ovaries. The hormones secreted by the ovaries affect the walls of the uterus.
(i) The breakdown of endometrium is characteristic of(a) proliferative phase (b) luteal phase (c) ovulatory phase (d) menstrual phase (ii) Which days of the menstrual cycle marks the proliferative phase?
(a) 1-5 (b) 15-28 (c) 6-13 (d) 10-14 (iii) Which of the following occurs during secretory phase?
(a) Empty Graafian follicle changes into corpus luteum. (b) Primary follicle changes' into Graafian follicle. (c) Endometrium rebuilds and estrogen secretion increases (d) LH surge inducing release of an ovum. (iv) Identify the hormones that attain peak level during ovulatory phase
(a) FSH (b) Progesterone (c) LH (d) Both (a) and (c) (v) Withdrawal of which hormone causes degeneration of corpus luteum?
(a) FSH (b) LH (c) Progesterone (d) Estrogen -
Read the following and answer any four questions from (i) to (v) given below:
A functional mammary gland is characteristic of all female mammals. Mammary glands are paired structures that contain glandular tissue and variable amount of fat. Refer to the given figure of a mammary gland and answer the following questions.
(i) Mammary glands are modified(a) sweat glands (b) sebaceous glands (c) sudoriferous glands (d) lacrimal glands. (ii) Identify the incorrectly matched pair.
(a) P - Areola (b) Q - Lactiferous duct (c) S - Mammary duct (d) T - Mammary alveoli (iii) Mammary ducts expand to form
(a) mammary alveoli (b) mammary ampullae (c) lactiferous ducts (d) mammary tubules. (iv) What is areola?
(a) Grape-like clusters of milk secreting structures (b) Fatty tissue between the mammary lobes (c) Circular pigmented area of skin around nipple (d) Connective tissue that supports the alveoli and ducts (v) Assertion: The size of breast depends on the amount of adipose tissue.
Reason: The adipose tissue supports the alveoli and the ducts.
(a) Both assertion and reason are true and reason is the correct explanation of assertion.
(b) Both assertion and reason are true but reason is not the correct explanation of assertion.
(c) Assertion is true but reason is false.
(d) Both assertion and reason are false. -
Read the following and answer any four questions from (i) to (v) given below:
In testis, the immature male germ cells produce sperms by spermatogenesis that begins at puberty. It occurs in the seminifer.o•. us tubules of the testes. Seminiferous tubules are lined by germinal epithelium. Study the schematic representation of spermatogenesis and answer the following questions.
(i) Which cell division occurs during multiplication phase?(a) Mitosis (b) Meiosis I (c) Meiosis II (d) Both (b) and (c) (ii) How many chromosomes are present in secondary spermatocyte and spermatid respectively?
(a) 46,23 (b) 46,46 (c) 23,23 (d) 23, XY (iii) Transformation of L into M is known as
(a) spermiation (b) spermateliosis (c) spermatogenesis (d) none of these (iv) Select the correct option
(a) Type A spermatogonia grows to larger primary spermatocyte. (b) One spermatogonium forms two spermatids. (c) Spermiation is the release of sperms from seminiferous tubules. (d) Primary spermatocyte undergoes mitosis to form secondary spermatocytes. (v) Which hormone acts on spermatogonia to stimulate sperm production?
(a) LH (b) GnRE (c) ABP (d) FSH -
Read the following and answer any four questions from (i) to (v) given below:
Study the given table and answer the questions based on it.Hormone Source Function (A) Oxytocin W Ejection of milk (B) X Anterior lobe of pituitary gland Stimulates secretion of ABP from Sertoli cells (C) Y Placenta Maintains corpus luteum to secrete progesterone (D) Relaxin Ovary Z (i) Identify the hormones X and Y respectively
(a) Testosterone, FSH (b) LH, hPL (c) FSH, hCG (d) ICSH, hCG (ii) W in the given table is
(a) hypothalamus (b) posterior lobe of pituitary (c) placenta (d) ovary (iii) Which of the following is correct for Z?
(a) Dilation of uterine cervix during labour pains. (b) Stimulates the growth of the mammary glands during pregnancy (c) Supports the fetal growth and prevents desiccation. (d) Forms protective plug in cervix of uterus during pregnancy. (iv) Which set of hormones is secreted only during pregnancy?
(a) Human chorionic gonadotropin, relaxin and human placental lactogen
(b) Human placental lactogen, estrogen and chorionic thyrotropin
(c) Human chorionic gonadotropin, human placental lactogen and progesterone
(d) Chorionic thyrotropin, chorionic gonadotropin and estrogen
(v) Assertion: Follicle stimulating hormone controls the maintenance and functions of male reproductive organs.
Reason: FSH acts directly on spermatogonia to stimulate sperm production.
(a) Both assertion and reason are true and reason is the correct explanation of assertion.
(b) Both assertion and reason are true but reason is not the correct explanation of assertion.
(c) Assertion is true but reason is false
(d) Both assertion and reason are false. -
Read the following and answer any four questions from (i) to (v) given below:
During copulation, semen is released by the penis into the vagina. The motile sperms swim rapidly, fuse with ovum in the ampullary region, resulting in fertilisation. Haploid nucleus of sperm fuse with that of ovum to form diploid zygote.
(i) In female genital tract, sperms are made capable of fertilising the egg. This phenomenon of sperm activation is called(a) amphimixis (b) cortical reaction (c) capacitation (d) acrosomal reaction (ii) Select the correct sequence of various physical and chemical events that take place during fertilisation
P. Fusion of cortical granules with plasma membrane of secondary oocyte.
Q. Formation of fertilisation cone to receive sperm.
R. Release of sperm lysin from acrosome.
S. Mixing up of chromosomes of a sperm and an ovum.(a) R \(\to\)Q\(\to\) P\(\to\) S (b) Q\(\to\) S \(\to\)R\(\to\) P (c) Q\(\to\) R \(\to\)S \(\to\)P (d) R\(\to\) P \(\to\)Q\(\to\) S (iii) Assertion: Only one sperm can fertilise an ovum
Reason: The secretion of acrosome help the sperm to enter into cytoplasm of ovum through zona pellucida and plasma membrane.
(a) Both assertion and reason are true and reason is the correct explanation of assertion.
(b) Both assertion and reason are true but reason is not the correct explanation of assertion.
(c) Assertion is true but reason is false.
(d) Both assertion and reason are false
(iv) What is the significance of fertilisation?(a) It restores haploid number of chromosomes. (b) It produces offspring genetically identical to parents. (c) It initiates cleavage (d) Both (b) and (c) (v) Site of fertilisation in humans is
(a) endometrium of uterine cavity (b) ampullary isthmic junction of oviduct (c) cervix of uterus (d) infundibulum of fallopian tube. -
Read the following and answer any four questions from (i) to (v) given below:
The mature ovum or a female gamete is spherical in shape. The human ovum is almost free of yolk and is said to be alecithal. Human ovum loses its ability to be fertilised about 24 hours after ovulation. Refer to the given structure of ovum and answer the following questions.
(i) Thick cellular layer formed of radially elongated follicular cells is(a) zona pellucida (b) plasma membrane (c) perivitelline membrane (d) corona radiata (ii) In humans, at which stage does ovum get released from ovary?
(a) Secondary oocyte (b) Oogonium (c) Primary oocyte (d) First polar body (iii) Cytoplasm of an ovum is enveloped by _________________ .
(a) zona pellucida (b) corona radiata (c) cell membrane (d) perivitelline space (iv) Select the correct option
V W X (a) Cytoplasm Zona pellucida Plasma membrane (b) Cortical granules Corona radiata Zona pellucida (c) Cortical granules Plasma membrane Corona radiata (d) Cytoplasm Corona radiata Zona pellucida (v) Which of the following is not a characteristic of an ovum?
(a) Nucleus of an ovum has prominent nucleolus (b) Only one ovum formed from one oogonium (c) It lacks centrioles (d) It has very small amount of ooplasm. -
Read the following and answer any four questions from (i) to (v) given below:
Each testicular lobule of testis contains .one to three highly coiled seminiferous tubules. Wall of each seminiferous tubule is formed of single layered germinal epithelium. Majority of cells in this epithelium are cuboidal called male germ cells. Study the transverse section of part of seminiferous tubule and answer the following questions.
(i) What is the characteristic of K?(a) K is spermatogonium which grows into primary spermatocyte (b) K is Sertoli cell which provides nutrition to spermatids (c) K is secondary spermatocyte which undergo meiosis II to form spermatid (d) K is spermatid being converted into sperm. (ii) Which of the following cell undergo reduction division to form secondary spermatocyte?
(a) J (b) M (c) L (d) K (iii) How many among the following have 46 chromosomes?
J, K, L, M, N,O (a) 2 (b) 4 (c) 5 (d) 3 (iv) Select an option that correctly identifies different labels
(a) L - Primary spermatocyte, N - Spermatozoa, M - Secondary spermatocyte (b) J - Spermatogonium, K - Sertoli cell, O - Spermatozoa (c) L - Primary spermatocyte, M - Secondary spermatocyte, N - Spermatozoa (d) J - Spermatogonium, K - Primary spermatocyte, N - Spermatid (v) Which hormone initiates spermatogenesis at puberty?
(a) FSH (b) ICSH (c) ABP (d) GnRH -
Read the following and answer any four questions from (i)to (v) given below:
Cleavage is the series of rapid mitotic divisions in zygote and forms blastula. The 2, 4, 8, 16 daughter cells are called blastomeres. Embryo with 64 blastomeres is known as blastocyst and has blastocoel cavity. Blastocyst gets implanted in uterine wall and leads to pregnancy.
(i) Solid mass of cells with 16 blastomeres is called(a) morula (b) blastula (c) gastrula (d) zygote (ii) At which stage of embryonic development trophoectoderm develops?
(a) Zygote (b) Morula (c) Blastula (d) Gastrula (iii) Site of implantation is
(a) endometrium of uterus (b) cervix (c) uterine fundus (d) infundibulum of oviduct. (iv) Correct sequence of various structures formed during embryonic development is
(a) Morula\(\to\) Embryo \(\to\)Gastrula \(\to\)Blastula (b) Zygote\(\to\) Embryo \(\to\)Morula\(\to\) Blastula (c) Blastula \(\to\)Morula \(\to\)Gastrula\(\to\) Embryo (d) Zygote \(\to\)Morula \(\to\)Blastula\(\to\) Gastrula. (v) Assertion: Side of blastocyst with inner cell mass is called animal pole.
Reason: Inner cell mass gives rise to embryo.
(a) Both assertion and reason are true and reason is the correct explanation of assertion.
(b) Both assertion and reason are true but reason is not the correct explanation of assertion.
(c) Assertion is true but reason is false.
(d) Both assertion and reason are false.
*****************************************
Human Reproduction Important Questions Answer Keys
-
(i) Testis
It produces the male gametes.
It secretes male hormone,testosterone.
(ii) Ovary
It produces the female gametes, ovary.
It secretes female hormones, estrogens and progesterone. -
(i) Spermiogenesis is the process of transformation of spermatids into flagellated spermatozoa.
(ii) Spermiation is the process of release of spermatozoa from the seminiferous tubules. -
Partiruition refers to the process of delivery if the fully-developed foetus,i.e.,childbirth.
Relaxin and oxytocin are the hormones involved in the process. -
Six eggs
Six eggs
-
The hormones involved in the process are:
(i) FSH, LH stimulate growth of follicle and maturation of ovum.
(ii) Oestrogen endometrial repair and growth.
(iii) Oestrogen and progesterone together prepare endometrium and other parts of the body for pregnancy. -
Each testicular lobule contains 1-3 highly coiled seminiferous tubules. Each tubule is lined on its inside by two types of cells. The cuboidal cells are called male germ (spermatogenic) cells and few large pyramidal (supporting cells- Sertoli or Nurse cells).
The former gives rise to sperms while the latter provide nutrition to the germ cells. -
Seminal fluid is a secretion of accessory sex glands of male that is, seminal vesicles, prostate gland and Cowper's glands. It is rich in fructose, calcium and certain enzymes.
-
1.lt helps it to survive and undergo meiosis II.
2.lt also helps in the nutrition of the zygote/embryo up to implantation. -
46 chromosomes (23 pairs).
-
Oxytocin.
-
The menstrual phase (menstruation) is followed by follicular or proliferative phase;it is under the influence of follicle stimulating hormone (FSH) from the anterior pituitary. The primary follicle matures into Graafian follicle;the follicular cells secrete estrogens,which control the growth and maintenence of the secondary sex organs like uterus,fallopian tube,ect. The FSH and lutenising hormone reach their peak level around the 14th day of menstrual cycle. The peak level of LH or LH surge causes the rupture of Graafian follicle and release of ovum;this process is called ovulation. It is followed by luteal phase,where LH influences the ruptured Graafian follicle to transform into corpus luteum. Corpus luteum secretes large quantity of progesterone in the luteal phase,which is necessary for the growth and maintenance of endometrium of uterus for implantation. If fertilisation does not occur,corpus luteum degenerates and progesterone is not secreted. The endometrium degenerates and menstruation occurs.
-
Hormones controlling spermatogenesis.
Spermatogenesis ids initiated by an increase in the secretion of GnRH (gonadotropin-releasing hormone) by the hypothalamus,at the age of puberty.
The increased levels of GnRH act on the anterior pituitary and stimulate it to secrete two gonaditropins namely:
(i) Follicle Stimulating Hormone (FSH) and
(ii) Luteinizing Hormone (LH).
LH acts o the Leydig cells and stimulates them to secrete testosterone.
FSH acts on Sertoli cells and stimulates them to secrete some factors which help in spermiogenesis. -
1.The male accesory ducts (which include rete testis,vasa efferentia,epididymis and vas deferens) are meant to store and transport the sperms from the testes to the outside through urethra.
2.The male accesory glands (which include a pair of seminal vesicles,a prostate and a pair of bulbourethral glands) secrete collectively the seminal plasma,which provides nutrients and a medium for the sperms to swim towards the ovum and also lubricate the penis. -
One
One
Two -
T.S.of Ovary
-
In our society,Women are blamed for giving birth to daughters. This is wrong because sex of the baby is determined by the sperm that can have either X or Y-chromosomes.
Since Women have only one type of chromosome (X) in all the ova.
If the sperm having X-chromosome fertilises the ovum (X), the resulting zygote (XX) will become a female.
If the sperm having Y-chromosome fertilises the ovum (X), the resulting zygote (XY) will become a male. -
The human male reproductive system consists of a scrotum, testes, testicular lobules, seminiferous tubules, urethra, and penis. The scrotum is a pouch of deeply pigmented skin divided into two separate sacs. Each sac contains one testis. Testes are the primary sex organs of the man. Each testicular lobules consists of 2-3 seminiferous tubules, blood vessels, nerves, and connective tissue. The male urethra is a common pathway for both semen and urine. The penis is the male copulatory organ and for conducting urine from the body.
-
-
Testes and ovaries are the primary sex organs in the males and females, respectively. Each testis bears large number of seminiferous tubules, which are the spermatogenic tissue of the testis. Similarly, ovaries bear the Graafian follicle or the ovarian follicles, which ultimately give rise to ovum. The testes secrete testosterone and the ovaries secrete oestrogen and progesterone
-
Spermatogenesis is the process of the production of sperms from the 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 first meiotic division (meiosis I), which is a reductional division to form two equal haploid secondary spermatocytes. Each secondary spermatocyte then undergoes 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.
-
Graafian follicle is a fluid-filled structure in the mammalian ovary which carries ovum development.
-
(a) Corpus luteum
It secretes large amounts of progesterone, which is essential for maintenance of the endometrium, implantation of embryo and other events of pregnancy.
(b) Endometrium
It is the inner most glandular lining of the wall of the uterus. - It undergoes cyclical changes during menstrual cycle and prepares itself for the implantation of embryo.
(c) Acrosome
The acrosome contains enzymes which help in dissolving the envelopes (zona pellucida and plasma membrane) of the ovum and facilitate the entry of sperm into the cytoplasm of the ovum.
(d) Sperm tail
It facilitates the movement of sperm inside the female reproductive tract to reach the ovum for fertilisation.
(e) Fimbriae
They help III collection of the ovum after ovulation, into the fallopian tube. -
(a) A. Seminal vesicle
B. Prostate gland
C. Bulbourethral gland
(i) Their secretions constitute seminal plasma.
(b) Testis is the primary sex organ and it is located in the scrotum. -
A. Acrosome
(i) The secretions.enzymes of acrosome dissolve the egg envelopes and help the sperm enter the cytoplasm of the ovum.
B. Mitochondria
(i) The mitochondria in the middle piece provide energy for the sperm motility in the female reproductive tract towards ovum.
C. Tail
(i) It facilitates the movement of sperm towards the ovum for fertilisation. -
(a) 1. Gonadotropin-releasing hormone (GnRH)
2. Follicle-stimulating hormone (FSH) Luteinising hormone (LH)
3. Testosterone
(b) (i) Leydig cells secrete testosterone.
(ii) Sertoli cells secrete some factors necessary for spermiogenesis. -
(i) 75 million
(b) 300 million
c) (i) 92 chromatids
(ii) 46 chromatids -
(A) (i) - (d), (ii) - (b), (iii) - (c), (iv) - (e)
(b) (i) - Luteinising hormone
(ii) - Progesterone -
(a) (i) It is called proliferative phase because the endometrium of the uterus is regenerated through prol iferation of its cells.
(ii) It is called follicular phase as the primary follicle in the ovary grows to become a fully mature Graafian follicle under the influence of follicle-stimulating hormone.
(b) (i) Corpus luteum is formed from the remaining parts of the ruptured Graafian follicle.
(ii) Corpus luteum secretes large amounts of progesterone. -
(a) X is hormone estrogen.
(i) It is secreted by the cells of the developing follicle.
Y is hormone progesterone.
(ii) It is secreted by corpus luteum.
(b) (i) X is secreted by the cells of the follicle during follicular phase before ovulation; after the rupture of Graafian follicle, there is no secretion of estrogen.
(ii) Y is secreted by corpus luteum that is formed after ovulation in the luteal phase; hence X peaks before Y. -
(a) X is luteinizing hormone (LH).
Y is follicle-stimulating hormone (FSH).
(b) Functions of X
(i) The LH-surge causes rupture of Graafian follicle and release of ovum, in the process, called ovulation.
(ii) It influences the formation of corpus luteum from the remaining parts of the Graafian follicle and secretion of progesterone from it.
Functions of Y
(i) It stimulates the growth of a primary follicleinto a Graafian follicle and thus, influences oogenesis.
(ii) It stimulates the cells of the developing follicle to secrete estrogens. -
(i) 1. Gonadotropin-releasing hormone (GnRH)
2. Follicle-stimulating hormone (FSH) and Luteinising hormone (LH)
3. Progesterone.
(b) Corpus luteum secretes progesterone. -
(a) A is a morula
B is a blastocyst.
Morula Blastocyst It is a solid sphere of8-16 blastomeres formed by cleavage of zygote It is a hollow sphere of cells, formed by the rearrangement of blastomeres. Zona pellucida is intact Zona pellucida disintegrates with the enlargement of blastocoel. -
(a) It is a blastocyst.
(b) 'a' is inner cell mass.
'b' is trophoblast.
(c) Stem cells are present in the inner cell mass.
(d) Role of Trophoblast.
(i) It becomes attached to the endometrium for implantation.
(ii) The chorionic villi appearing on it form the foetal part of placenta. -
(b) They induce mild uterine contractions, called foetal ejection reflex.
(c) This triggers the release of oxytocin from the maternal pituitary.
(e) The stimulatory reflex between the uterine contractions and oxytocin secretion continues and results in stronger and stronger uterine contractions.
(f) This leads to expulsion of the foetus through the birth canal, i.e., parturition.
-
(i) (b) : P is an epididymis that stores the sperms and secretes a fluid which is considered to nourish the sperms
(ii) (b) : Q - Vas deferens, R - Ejaculatory duct S - Bulbourethral gland, T - Seminal vesicle
(iii) (c) :Q (vas deferens) arises from cauda epididymis
(iv) (d)
(v) (a) -
(i) (c) : FSH stimulates the growth of Graafian follicles, development of egg oocyte within the follicles to complete the meiosis I to form secondary oocyte. It also stimulates the formation of estrogen.
(ii) (d) : LH induces rupture of mature Graafian follicle and thereby the release of secondary oocyte.
(iii) (c) : FSH stimulates the growth of Graafian follicles, development of egg oocyte within the follicles to complete the meiosis I to form secondary oocyte. It also stimulates the formation of estrogen.
(iv) (a)
(v) (d) : The rising level of progesterone inhibits the release of GnRH, which in turn inhibits production of FSH, LH and progesterone. -
(i) (d): During menstrual phase, the endometrium breaks down and menstruation begins.
(ii) (c) : Proliferative phase extends for about 10-12 days usually from day 6th to 13th in a 28 day cycle
(iii) (a)
(iv) (d) : During ovulatory phase, both LH and FSH attain a peak level
(v) (b) -
(i) (a)
(ii) (d) : T is mammary ampulla and R is mammary alveoli.
(iii) (b) : Near the nipple, mammary ducts expand to form mammary ampullae where some milk may be stored before going to lactiferous ducts.
(iv) (c)
(v) (c) : The fibrous (connective) tissue supports the alveoli and the ducts. -
(i) (a): In multiplication phase, the undifferentiated primordial germ cells divide several times by mitosis to produce large number of spermatogonia
(ii) (c)
(iii) (b) : Transformation of spermatids (L) into spermatozoa (M) is known as spermiogenesis or spermateliosis
(iv) (c)
(v) (d) : FSH acts on spermatogonia to stimulate sperm production -
(i) (c)
(ii) (b)
(iii) (a) : Relaxin increases the flexibility of the pubis symphysis and ligaments of sacroiliac and sacrococcygeal joints and helps to dilate the uterine cervix during labour pains.
(iv) (a) : hPL, hCG and relaxin are produced in women only during pregnancy.
(v) (b) -
(i) (c) : The secretions of female genital tract remove coating substances deposited on the surface of the sperms. This phenomenon of sperm activation is called capacitation
(ii) (d)
(iii) (b) : Binding of sperm to the secondary oocyte induces depolarisation of the oocyte plasma membrane. Depolarisation prevents polyspermy and ensures monospermy
(iv) (c) : Fertilisation restores diploid number of chromosomes. It introduces variations as it combines characters of the two parents.
(v) (b) -
(i) (d)
(ii) (a) : In humans, ovum is released from the ovary as secondary oocyte
(iii) (c)
(iv) (b) : V - Cortical granules
W - Cells of corona radiata
X - Zona pellucid a
Y - Perivitelline space
Z - Plasma membrane
(v) (d) : Ovum has large amount of cytoplasm called ooplasm -
(i) (b)
(ii) (c) : J - Spermatogonium,
K - Sertoli (sustentacular) cell,
L - Primary spermatocyte,
M- Secondary spermatocyte
N - Spermatid,
O- Spermatozoa
(iii) (a): Spermatogonium and primary spermatocytes are diploid (2N), i.e., 46 chromosomes
(iv) (b)
(v) (d) : Spermatogenesis starts at puberty due to significant increase in the secretion of GnRH. -
(i) (a) : Embryo with 8-16 blastomeres is solid mass of cells, known as morula.
(ii) (c) : Embryo with 64 cells is called blastula (blastocyst) and has blastocyst cavity. Blastocyst is composed of an outer envelope of cells called trophoblast and inner cell mass.
(iii) (a) : Implantation is the attachment of blastocyst to the uterine wall. The portion of blastocyst where the inner cell mass is located lies against the endometrium of uterus.
(iv) (d)
(v) (b)
