CBSE Class 12 Biology Human Reproduction Worksheet

Question. Which of the following are included in barrier method ?
(a) Condoms
(b) Diaphrams
(c) Cervical caps and vault
(d) All of the above
Answer : D

Question. Zona pellucida is synthesised by :
(a) Follicle cells
(b) Oocyte
(c) Both follicle cells and Oocyte
(d) Granulosa cells
Answer : B

Question. Which of the following statements is correct forSaheli ?
(a) It is weekly pill.
(b) It has high contraceptive value
(c) It has nonsteroidal preparation
(d) All the above
Answer : D

Question. Corpus luteum is formed by :
(a) Granulosa cells
(b) Interstitial cells
(c) Follicle cells + Granulosa cells
(d) Granulosa cells + Theca cells
Answer : D

Question. Couple unable to produce children inspite of unprotected sexual co-habitation is termed as :
(a) Impotency
(b) Infertility
(c) STD
(d) PID
Answer : B

Question. The head of sperm contains the nucleus having a haploid set of chromosomes in a :
(a) Compact and inactive state
(b) Compact and active state
(c) Rare and inactive state
(d) Rare and active state
Answer : A

Question. Placenta acts as a/an :
(a) Ultrafilter
(b) Endocrine gland
(c) Both (1) and (2)
(d) None of above
Answer : C

Question. Infertility cases due to inability of male partner to inseminate the female corrected by :
(a) ZIFT
(b) GIFT
(c) Artificial insemination
(d) ICSI
Answer : C

Question- Which of the following stage of oogenesis forms a membrane called zona pellucida surrounding it?
(a) Oogonia
(b) Polar body
(c) Corpus luteum
(d) Secondary oocytes
Answer : D

Question- After birth, colostrum is released from mammary glands which is rich in
(a) fat and low in proteins
(b) proteins and low in fat
(c) proteins, antibodies and low in fat
(d) proteins, fat and low in antibodies
Answer : C

Question-In the process of spermatogenesis, first maturation division is called _______.
(a) mitotic division
(b) reduction division
(c) amitotic division
(d) None of the these
Answer : B

Question-Level of which hormones are at their highest during the luteal phase (second half of the cycle) of the menstrual cycle?
(a) Estrogen
(b) Progesterone
(c) Luteinizing hormone
(d) Follicular stimulating hormone
Answer : B

Question-Which phase of menstrual cycle is also called proliferative phase?
(a) Luteal
(b) Ovulatory
(c) Follicular
(d) Menstruation
Answer : C

Question-In humans, male germs cells differentiate into _____ at the end of first meiotic division.
(a) spermatid
(b) spermatogonium
(c) secondary spermatocyte
(d) primary spermatocyte
Answer : C

Question-Which phase of menstrual cycle is also called secretory phase?
(a) Luteal
(b) Ovulatory
(c) Follicular
(d) Menstruation
Answer : A

Question- Menstruation is triggered by a sudden decline in the amount of hormone secreted by corpus luteum. Identify the hormone.
(a) Luteinizing hormone
(b) Follicle stimulating hormone
(c) Progesterone
(d) Estrogen
Answer : C

Question-Which of the following indicates pregnancy?
(a) Lack of menstruation.
(b) Occurrence of menstrual flow.
(c) When released ovum is not fertilized.
(d) When Graafian follicle matures and endometrium regenerates through proliferation.
Answer : A

Question-Which of the following contains a fluid filled cavity called antrum?
(a) Primary spermatocyte.
(b) Primary follicle of ovary.
(c) Tertiary follicle of ovary.
(d) Secondary spermatocyte.
Answer : C

Question-At the time of implantation, the human embryo is called _______.
(a) zygote
(b) blastocysts
(c) embryo
(d) foetus
Answer : B

Question-By which process sperms released from the seminiferous tubules?
(a) Spermiation
(b) Insemination
(c) Spermatogenesis
(d) Spermiogenesis
Answer : A

Question-Spermatids are transformed into sperm by a process called_______.
(a) spermiation
(b) implantation
(c) insemination
(d) spermiogenesis
Answer : D

Question-Vasa efferentia are the ductules leading from
(a) epididymis to urethra.
(b) vas deferens to epididymis.
(c) rete testis to vas deferens.
(d) testicular lobules to rete testis.
Answer : C

Question-Increased secretion of which hormone start the process of sperm formation at the time of puberty?
(a) GH
(b) TSH
(c) PRL
(d) GnRH
Answer : D

Question- When semen is released by the penis into the vagina during copulation, then it is called _____.
(a) ovulation
(b) insemination
(c) menstruation
(d) gametogenesis
Answer : B

Question-Which of the following hormone maintains the function of male sex accessory gland and ducts?
(a) Estrogen
(b) Androgen
(c) Progesterone
(d) Luteinizing hormone
Answer : B

Question-Semen is a constituent of seminal plasma with _______.
(a) ovum
(b) sperm
(c) zygote
(d) follicle
Answer : B

Question- Ejaculation of human male contains about 200 – 300 million sperms, of which for normal fertility ____ % sperms must have normal shape and size and at least ____% must show energetic motility.
(a) 40, 60
(b) 50, 50
(c) 60, 40
(d) 30, 70
Answer : C

Question-Which of the following produces sperms in spermatogenesis?
(a) Sertoli cells.
(b) Interstitial cells.
(c) Primary spermatocytes.
(d) Immature male germ cells.
Answer : D

Question. Extrusion of second polar body from egg nucleus occurs 
(a) after fertilisation
(b) before the entry of sperm into ovum
(c) simultaneously with first cleavage
(d) after the entry of sperm but before fertilisation
Answer : D

Question. Menstrual flow occurs due to the lack of
(a) progesterone
(b) FSH
(c) oxytocin
(d) vasopressin
Answer : A

Question. In an ideal menstrual cycle, the menstrual phase last for
(a) 3-5 days
(b) 5-6 days
(c) 1-3 days
(d) 2-3 days
Answer : A

Question. Cessation of menstrual cycle at the age of 50 is called
(a) ovulation
(b) gametogenesis
(c) menses
(d) menopause
Answer : D

Question. A regular cycling woman is not menstruating, which one of the following is the most likely to be the root cause?
(a) Maintenance of the hypertrophical endometrial lining
(b) Maintenance of high concentration of sex-hormones in the bloodstream
(c) Regression of well-developed corpus luteum
(d) Fertilisation of the ovum
Answer : D

Question. What happens during the follicular phase of menstrual cycle?
(a) Proliferation of endometrium
(b) Reduction in blood supply to endometrium
(c) Regression of endometrium
(d) No effect on endometrium
Answer : A

Question. Level of LH is maximum
(a) just before ovulation
(b) just after ovulation
(c) at the time of ovulation
(d) during menstrual bleeding phase
Answer : C

Question. When does ovulation occur in a healthy menstruating female?
(a) 9-14 days
(b) 14-16 days
(c) 16-28 days
(d) 20-26 days
Answer : B

Question. Which of the following events is not associated with ovulation in human female?
(a) Decrease in oestradiol
(b) Full developement of Graafian follicle
(c) Release of secondary oocyte
(d) LH surge
Answer : A

Question. No new follicles develop in the luteal phase of the menstrual cycle because
(a) follicles do not remain in the ovary after ovulation
(b) FSH levels are high in the luteal phase
(c) LH levels are high in the luteal phase
(d) Both (b) and (c)
Answer : A

Question. Formation of corpus luteum is induced by
(a) LH
(b) oestrogen
(c) FSH
(d) progesterone
Answer : A

Question. Rapid secretion of LH in ovulatory phase causes
(a) rupturing of Graafian follicle
(b) release of ova
(c) ovulation
(d) All of the above
Answer : D

Question. A temporary endocrine gland in the human body is
(a) pineal gland
(b) corpus cardiacum
(c) corpus luteum
(d) corpus allatum
Answer : C

Question. The main function of mammalian corpus luteum is to produce
(a) oestrogen only
(b) progesterone only
(c) human chorionic gonadotropin
(d) relaxin only
Answer : B

Question. In human females, meiosis-II is not complete until
(a) puberty
(b) fertilisation
(c) uterine implantion
(d) birth
Answer : B

Question. Endometrium, epithelial glands and connective tissue of uterus are broken due to the
(a) lack of oestrogen
(b) lack of progesterone
(c) lack of FSH
(d) excess of FSH
Answer : B

Question. Inner cell mass or embryoblast gives rise to
(a) foetal part
(b) embryo
(c) notochord
(d) nourishment cell
Answer : B

Question. Which of them is not a correct match?
(a) Proliferative phase–Rapid regeneration of myometrium and maturation of Graafian follicle
(b) Secretory phase–Development of corpus luteum and increased secretion of progesterone
(c) Menstruation–Breakdown of endometrium
(d) Ovulation–LH and FSH attain peak level and cause rupture of Graafian follicle
Answer : A

Question. Some important events in the human female reproductive cycle are given below. Arrange the events in proper sequence.
I. Secretion of FSH.
II. Growth of corpus luteum.
III. Growth of the follicle and oogenesis.
IV. Ovulation.
V. Sudden increase in the levels of LH.
Choose the correct option.
(a) III→ I→ IV→ II→ V
(b) I→ III→ V→ IV→ II
(c) I→ IV→ III→ V→ II
(d) II→ I→ III→ IV→ V
Answer : B

Question. The sex of the foetus will be decided at
(a) fertilisation by male gamete
(b) implantation
(c) fertilisation by female gamete
(d) the start of cleavage
Answer : A

Question. Cleavage is the rapid mitotic division occurring on the way through isthmus to oviduct. It occurs in
(a) gametes
(b) zygote
(c) sperm
(d) ova
Answer : B

Question. Capacitation occurs in 
(a) rete testis
(b) epididymis
(c) vas deferens
(d) female reproductive tract
Answer : D

Question. The reproductive cycle in the female primates such as monkeys, apes and human beings is called
(a) menstrual cycle
(b) oestrus cycle
(c) circadian cycle
(d) ovulatory cycle
Answer : A

Question. If the mammalian ovum fails to get fertilised, which one of the following is likely to happen?
(a) Corpus luteum will degenerate
(b) Oestrogen secretion further decreases
(c) Primary follicle starts developing
(d) Progesterone secretion rapidly increases
Answer : A

Question. The first menstruation that begins at puberty is called
(a) menopause
(b) ovulation
(c) gametogenesis
(d) menarch
Answer : D

Question. Fertilisation in humans is practically feasible only if
(a) the ovum and sperms are transported simultaneously to ampullary-isthmic junction of the Fallopian tube
(b) the ovum and sperms are transported simultaneously to ampullary-isthmic junction of the cervix
(c) the sperms are transported into cervix within 48 hrs of release of ovum in uterus
(d) the sperms are transported into vagina just after the release of ovum in Fallopian tube
Answer : A

Question. Correct sequence of secretion of hormone from beginning of menstrual cycle to the end is
(a) FSH, progesterone, LH
(b) oestrogen, FSH and progesterone
(c) FSH, oestrogen, progesterone
(d) oestrogen, progesterone, FSH
Answer : C

85Question.(a) ampulla
(b) cervix
(c) endometrium
(d) myometrium
Answer : A

Question. During fertilisation, a sperm comes in contact with the zona pellucida layer of the ovum and induces changes in the membrane that block the entry of …A… . The secretions of the …B… help the sperm enter into the cytoplasm of the ovum.
                 A                     B
(a) eggs zona                 pellucida
(b) eggs                         acrosome
(c) additional sperms      acrosome
(d) additional sperms      zona pellucida
Answer : C

Question. What is acrosomal reaction? 
(a) Contact of sperms with eggs
(b) Digestion of zona pellucida
(c) Disintegration of acrosome
(d) Contact of acrosome and nucleus of egg
Answer : B 

Question. Cleavage forms 2-4-8-16 cells. These cells are called
(a) blastocysts
(b) blastomeres
(c) morula
(d) trophoblast
Answer : B

Question. Embryo at 8-16 cells stage is called
(a) blastula
(b) morula
(c) trophoblast
(d) All of these
Answer : B

Question. Trophoblast of blastocyst attaches to the
(a) endometrium
(b) myometrium
(c) perimetrium
(d) mesoderm
Answer : A

Pregnancy and Embryonic Development

Question. After implantation, finger-like projections appear on the trophoblast called … A… . They are surrounded by … B… and maternal blood.
Here, A and B refer to
(a) A–chorion, B–foetal cell
(b) A–chorionic villi, B–uterine tissue
(c) A–uterine tissue, B–chorionic villi
(d) A–foetal cell, B–chorion
Answer : B

Question. Chorionic villi and uterine tissue become interdigitated with each other and jointly form
(a) trophoblast
(b) inner cell mass
(c) placenta
(d) embryo
Answer : C

Question. Several hormones like hCG, hPL, oestrogen, progesterone are produced by 
(a) ovary
(b) placenta
(c) Fallopian tube
(d) pituitary
Answer : B

Question. Hormones secreted by the placenta to maintain pregnancy are
(a) hCG, hPL, progestogens, oestrogens
(b) hCG, hPL, oestrogens, relaxin, oxytocin
(c) hCG, hPL, progestogens, prolactin
(d) hCG, progestogens, oestrogens, glucocorticoids
Answer : A

Question. Which one is present in the urine of pregnant woman?
(a) hCG
(b) LH
(c) Oestrogen
(d) FSH
Answer : A

Question. Structure analogous to the placenta in mammals.
(a) Chorion
(b) Amnion
(c) Yolk sac
(d) Allantois
Answer : A

Question. Relaxin (a hormone) is secreted by
(a) placenta
(b) ovary
(c) anterior lobe of pituitary
(d) posterior lobe of pituitary
Answer : B

Question. Soon after implantation, the inner cell mass differentiates into outer …A…, middle …B… and an inner …C… . A, B and C in the given sentence are
(a) A–mesoderm, B–ectoderm, C–endoderm
(b) A–ectoderm, B–mesoderm, C–endoderm
(c) A–ectoderm, B–endoderm, C–mesoderm
(d) A–mesoderm, B–endoderm, C–ectoderm
Answer : B

Question. Identify the correctly matched pair/pairs of the germ layers and their derivatives.
I. Ectoderm – Epidermis II. Endoderm – Dermis
III. Mesoderm – Muscles IV. Mesoderm – Cartilage
V. Endoderm – Enamel of teeth
Choose the option containing the correctly matched pairs.
(a) I and IV
(b) I and II
(c) I, III and IV
(d) I, II, III and V
Answer : C

Question. The amnion of mammalian embryo is derived from
(a) mesoderm and trophoblast 
(b) endoderm and mesoderm
(c) ectoderm and mesoderm
(d) ectoderm and endoderm
Answer : C

Question. Gastrulation means 
(a) conversion of blastula into morula
(b) formation of three germ layers
(c) a phase in which organogenesis takes places
(d) a phase chracterised by inner cell mass
Answer : B

Question. The correct sequence is
(a) Zygote→ Cleavage→ Morula→ Blastula→ Gastrula
(b) Cleavage→ Zygote→ Morula→ Blastula→ Gastrula
(c) Zygote→ Morula→ Blastula→ Cleavage→ Gastrula
(d) Zygote→ Blastula→ Morula→ Cleavage→ Gastrula
Answer : A

Question. Choose the incorrect pair.
Organ                                    Time of development in foetus
(a) Heart                                After one month of pregnancy
(b) Limbs and digits                By the end of second month
(c) External genital organs       By the end of 24 weeks (second trimester)
(d) First movement of foetus    During the fifth month
Answer : C

ONE MARK QUESTIONS

1 State the function of sertoli cells.

2 What technical term is given to an embryo in its 16 celled stage.

TWO MARK QUESTIONS

3 Where are fimbriae present in human female reproductive system? Give their function.

4 Where are Leydig cells present? What is their role in reproduction?

5 Placenta acts as an endocrine tissue. Justify.

6 Differentiate between menarch and menopause.

7 Mention the fate of Corpus Luteum and its effect on the uterus in absence of fertilisation of the ovum in a human female.

8 Spermatogenesis in human males is a hormone regulated process. Justify.

9 Draw a labeled diagram of the microscopic structure of a human sperm.

10 Draw a labeled diagram of a sectional view of human ovary showing various stages of follicles growing in it.

3 MARK QUESTIONS

11 Study the figure given below and answer the questions that follow:
a) Name the stage of human embryo the figure represents.
b) Identify ‘a’ in the figure and mention its function.
c) Mention the fate of the inner cell mass after implantation in the uterus.
d) Where are the stem cells located in this embryo?

Very Short Answer Type Question

Question. Write the function of each of the following :
(i) Luteinizing hormone in human males
(ii) Middle piece of human sperm.
Answer : (i) Luteinizing hormone (LH) stimulate leydig cell to secrete androgens which in turn stimulate spermatogenesis.
(ii) There are numerous mitochondria in the middle piece of sperms which produce energy which is required for the movement of sperms.

Question. Mention the difference between spermiogenesis and spermiation. 
Answer : Spermiogenesis is the process of development of spermatozoan from spermatids, while spermiation is the maturation and releasing of sperms.
Spermiogenesis occurs over sertoli cells while during spermiation, the sperms detach from sertoli cells.

Question. How does the sperm penetrate through the zona pellucida in the human ovum ?
Answer : Acrosome present at the tip of the sperm helps to penetrate through the zona pellucida in human ovum. 

Question. Write the physiological reason, why a woman generally cannot conceive a child after 50 years of age ?
Answer : In human beings, menstrual cycle ceases around at 50 years of age and there will be no production of egg. It is the phase in a woman’s life when menopause occurs, ovulation and menstruation stop. Hence, a woman cannot conceive a child after 50 years of age. 

Short Answer Type Question

Question. Mention the relationship between concentration of luteinising hormone and maintenance of endometrium in the human uterus.
Answer : (Mid cycle) LH surge → formation of corpus luteum → progesterone, maintain the growth of endometrium.

Question. Name the stage of human embryo at which it gets implanted. Explain the process of implantation.
Answer : The embryo gets implanted at blastocyst stage.
The trophoblast gets attached to the endometrium uterine wall of mother by a process called implantation and the inner mass of cells gets differentiated as embryo. After attachment the uterine cells divide rapidly and cover the blastocyst.
As a result the blastocyst gets embedded in the endometrium of the uterus. 

Question. Explain the events in a normal woman during her menstrual cycle on the following days :
(i) Ovarian event from 13-15 days
(ii) Ovarian hormones level from 16 to 23 days
(ii) Uterine events from 24 to 29 days.
Answer : (i) Rupture of Graafian follicle leads to ovulation/ release of ovum.
(ii) Estrogen level is low.
(iii) Disintegration of endometrium and menstrual cycle begins again.

Question. Enumerate the events in the ovary of a human female during :
(i) Follicular phase,
(ii) Luteal phase of menstrual cycle.
Answer : (i) Follicular phase : Follicular phase is also called the proliferative phase. During the phase, the FSH released by the pituitary stimulates the growth of the primary ovarian follicles and also causes maturation of the primary oocyte in this follicle. The follicular cells of the Graafian follicle secrete estrogen.
Due to an increased level of estrogen the uterine endometrium becomes thick, more vascular and more glandular. This phase lasts for about 10 to 14 days or until ovulation occurs.
(ii) Luteal phase : Development of corpus luteum, secretion of progesterone.

Long Answer Type Questions

Question. Given below is the diagram of a human ovum surrounded by a few sperms. Observe the diagram and answer the following questions :
(i) Compare the fate of sperms shown in the diagram.
(ii) What is the role of zona pellucida in this process ?
(iii) Analyze the changes occurring in the ovum during the process.
(iv) How is the entry of sperm into the ovum facilitated ?
(v) Specify the region of female reproductive system where the event represented in the diagram takes place.
Answer : (i) A is able to penetrate / fertilize the ovum, whereas B and C are unable to penetrate / fertilize // B and C will degenerate.
(ii) Zona pellucida ensures the entry of only one sperm into the ovum 
(iii) Induces completion of meiotic division of the secondary oocyte, formation of second polar body and a haploid ovum
(iv) Enzymes of acrosome help (½ mark if only ‘acrosome‘ is written) 
(v) Ampullary – isthmic junction of the fallopian tube 

Question. (i) Briefly explain the events of fertilization and implantation in an adult human female.
(ii) Comment on the role of placenta as an endocrine gland. 
Answer : (i) (a) On the 14th day of menstrual cycle, ovulation takes place which releases secondary oocyte.
(b) This secondary oocyte is caught by fimbriae and it starts moving up the fallopian tube.
(c) In the meantime, sperms which have been deposited in vagina start moving up and reach the fallopian tube.
(d) The two meet at ampullary isthmus junction and fuse together.
(e) After entry of sperm secondary oocyte completes its meiosis II, changes the ovum and fuse with sperm’s pronuclei leading to zygote formation.
(f) This zygote after sometime starts dividing.
It changes to morula (8-16 celled), which continues to divide to form the blastocyst. The morula moves further into the uterus.
(g) The cells in the blastocyst are arranged into an outer trophoblast and an inner cell mass.
(h) The trophoblast gets attached to the uterine endometrium and the process is called implantation. This leads to pregnancy. The inner cell mass gets differentiated to form the embryo. 
(ii) Placenta as endocrine gland produces :
(a) hCG (Human Chorionic Gonadotropin)
(b) hPL (Human Placental Lactogen)
(c) Oestrogen
(d) Progesterone
(e) In the later stages of pregnancy, it also releases relaxin. These hormones support foetal growth and help in maintaining pregnancy. 

Question. (a) Explain menstrual cycle in human females.
(b) How can the scientific understanding of the menstrual cycle of human females help us a contraceptive measure ?
Answer : (a) (i) Menstrual Phase : Menstrual flow occurs / due to breakdown of endometrial lining of uterus, when fertilization does not occur.
(ii) Follicular Phase : Primary follicles grow into mature graafian follicles and endomentrium regenerates through proliferation, changes induced by pituitary and ovarian hormones.
(iii) Ovulatory Phase : LH surge, induces rupture of graafian follicle and release of secondary oocyte /ovum during middle of cycle (i.e. 14th day).
(iv) Luteal phase : Ruptured graafian follicle transforms into corpus luteum which secrete large amount of progesterone, essential for maintaining endometrium. 
(b) Because ovulation occurs during mid cycle chances of fertilization are very high so, couples should abstain from coitus between day 10 – 17.

Question. When and where are primary oocytes formed in a human female ? Trace the development of these oocytes till ovulation (in menstrual cycle). How do gonadotropins influence this developmental process ?
Answer : (i) The primary oocytes are formed in the foetal ovary during the development of the foetus. The ovum is formed by the process of oogenesis. 
(ii) During embryonic growth, millions of gamete mother cells (oogonia) are formed in the foetal ovary. These cells undergo meiosis, but get temporarily arrested at prophase and are called primary oocytes. Before reaching puberty, a large number of primary oocytes degenerate and the remaining ones get surrounded by layers of granulosa cells and a new theca. These are called secondary follicles. The secondary follicles are then converted into tertiary follicles that have characteristic fluid-filled cavity called antrum. At this stage, the primary oocyte present within the tertiary follicle completes meiosis, which results in the formation of haploid secondary oocyte and a tiny polar body. This tertiary follicle further changes into the Graafian follicle. The secondary oocyte in the Graafian follicle is surrounded by the zona pellucida. Then, the Graafian follicle ruptures to release the ovum by ovulation. 
(iii) Role of gonadotropins : The gonadotropins (Follicle Stimulating Hormone and the Luteinising Hormone) are released by the anterior portion of the pituitary gland. The maturation of the primary follicles into the Graafian follicles occurs during the follicular phase. The secretion of gonadotropins increases during this phase, cause follicular growth and the growing follicles produce oestrogen. The LH and FSH are at their peak in the middle of the cycle (14th day) and cause the rupture of the Graafian follicles to release ovum. This phase is called the ovulatory phase. 

Question. (i) Write the specific location and the functions of the following cell in human male :
(a) Leydig cells
(b) Sertoli cells
(c) Primary spermatocyte
(ii) Explain the role of any two accessory glands in human male reproductive system. 
Answer : (i) (a) Leydig cells :

(ii) Location : Outside seminiferous tubules / Interstitial space.
Function : Synthesize or secrete male hormones / Testicular hormones / Androgens.
(b) Sertoli cells :

(i) Location : Lined inside the seminiferous tubules.
Function : Provide nutrition to the germ cells / sperms.

(c) Primary spermatocytes found in the inner lining of seminiferous tubules. They undergo meiosis and form sperms. 
(ii) The accessory glands are seminal vesicle, prostate gland, bulbourethral gland. 
Secretion of these glands constitute seminal plasma which is rich in fructose, calcium and certain enzymes provide nourishment to sperms, secretion of bulbourethral glands also help in lubrication of penis.