Human Reproduction: Questions and Answers (Evaluation)

Evaluation

1. The mature sperms are stored in the

a. Seminiferous tubules

b.Vas deferens

c. Epididymis

d. Seminal vesicle

Answer: c) Epididymis

2. The male sex hormone testosterone is secreted from

a. Sertoli cells

b. Leydig cell

c. Epididymis

d. Prostate gland

Answer: b) Leydig cell

3. The glandular accessory organ which produces the largest proportion of semen is

a. Seminal vesicle

b. Bulbourethral gland

c. Prostate gland

d. Mucous gland

Answer: a) Seminal vesicle

4. The male homologue of the female clitoris is

a. Scrotum

b. Penis

c. Urethra

d.Testis

Answer: b) Penis

5. The site of embryo implantation is the

a. Uterus

b. Peritoneal cavity

c. Vagina

d. Fallopian tube

Answer: a) Uterus

6. The foetal membrane that forms the basis of the umbilical cord is

a. Allantois

b. Amnion

c. Chorion

d. Yolk sac

Answer: a) Allantois

7. The most important hormone in intiating and maintaining lactation after birth is

a. Oestrogen

b. FSH

c. Prolactin

d. Oxytocin

Answer: c) Prolactin

8. Mammalian egg is

a. Mesolecithal and non cleidoic

b. Microlecithal and non cleidoic

c. Alecithal and non cleidoic

d. Alecithal and cleidoic

Answer: c) Alecithal and non cleidoic

9. The process which the sperm undergoes before penetrating the ovum is

a. Spermiation

b. Cortical reaction

c. Spermiogenesis

d. Capacitation

Answer: Capacitation

10. Painful menstruation is termed as

a. Dysmenorrhoea

b. Menorrhagia

c. Amenorrhoea

d. Oligomenorrhoea

11. The milk secreted by the mammary glands soon after child birth is called

a. Mucous

b. Colostrum

c. Lactose

d. Sucrose

Answer: b) Colostrum

11B. Colostrum is rich in

a. Ig E

b. Ig A

c. Ig D

d. Ig M

12. The Androgen Binding Protein (ABP) is produced by

a. Leydig cells

b. Hypothalamus

c. Sertoli cells

d. Pituitary gland

Answer: c) Sertoli cells

13. Which one of the following menstrual irregularities is correctly matched?

a. Menorrhagia – excessive menstruation

b. Amenorrhoea - absence of menstruation

c. Dysmenorrhoea - irregularity of menstruation

d. Oligomenorrhoea – painful menstruation

Answer: b) Amenorrhoea - absence of menstruation

14. Find the wrongly matched pair

a. Bleeding phase - fall in oestrogen and progesterone

b. Follicular phase - rise in oestrogen

c. Luteal phase - rise in FSH level

d. Ovulatory phase - LH surge

Answer: c) Luteal phase - risein FSH level

Answer the following type of questions

Assertion (A) and Reason (R)

a. A and R are true, R is the correct explanation of A

b. A and R are true, R is not the correct explanation of A

c. A is true, R is false

d. Both A and R are false

15. A – In human male, testes are extra abdominal and lie in scrotal sacs.

R – Scrotum acts as thermoregulator and keeps temperature lower by 2oC for normal sperm production .

a. A and R are true, R is the correct explanation of A

b. A and R are true, R is not the correct explanation of A

c. A is true, R is false

d. Both A and R are false

(a) A and R are true, R is the correct explanation of A

Answer: a) A and R are true, R is the correct explanation of A

16. A – Ovulation is the release of ovum from the Graafian follicle.

R – It occurs during the follicular phase of the menstrual cycle.

a. A and R are true, R is the correct explanation of A

b. A and R are true, R is not the correct explanation of A

c. A is true, R is false

d. Both A and R are false

Answer: c) A is true, R is false

17. A – Head of the sperm consists of acrosome and mitochondria.

R – Acrosome contains spiral rows of mitochondria.

a. A and R are true, R is the correct explanation of A

b. A and R are true, R is not the correct explanation of A

c. A is true, R is false

d. Both A and R are false

d) Both A and R are false

18. Mention the differences between spermiogenesis and spermatogenesis.

Spermiogenesis

Transformation of spermatids into mature spermatozoa is called spermiogenesis

Spermatogenesis

Production of male gemetes (sperms) in the seminiferous tabules of the testes is called spermatogenesis.

19. At what stage of development are the gametes formed in new born male and female?

Male :

• Spermatogenesis starts at the age of puberty. It is initiated by the release of Gonadotropin Releasing Hormone (GnRH) by the hypothalamus.

Female :

• During foetal development, oogonia or egg mother cells are formed in the foetal ovary. Primary oocytes are formed and they are temporarily arrested at this stage. At puberty secondary oocyte is formed from primary oocytes and the ovum is formed during fertilization.

20. Expand the acronyms

a. FSH b. LH c. hCG d. hPL

a) FSH - Follicle stimulating Hormones.

b) LH - Luteinzing Hormone

c) hCG - human Chorionic Gonadotropin

d) hPL - human Placental Lactogen.

21. How is polyspermy avoided in humans?

• Fertilisation is accomplished when sperm fuses with a ovum.

• Next, the cortical granules from the cytoplasm of the ovum from a barrier around the ovum. This is called fertilisation membrane.

• It prevents the further penetration of other sperms. Thus poly spermy is prevented.

22. What is colostrum? Write its significance.

• Colostrum is a nutrient rich fluid produced by human female immediately after parturition.

• It is yellowish, It has immune, growth and tissue repair factors.

• It is a natural antimicrobial agent stimulating the infant's immune system.

• It has less lactose. It has no fat. It has proteins, vitamin A, minerals.

• It is rich in IgA antibodies.

• It protects the injant's digestive tract against bacterial infection.

23. Placenta is an endocrine tissue. Justify.

During pregnancy, the placenta acts as a temporary endocrine gland. It produces the following hormones.

• hCG - human Chorionic Gonadotropin.

• human chorionic somatomammotropin. (hCS) (or) human placenal Lactogen (hPL)

• Oestrogen

• Progesterone

• Relaxin (relax pelvic ligaments during parturition)

Thus hormones are essential for a normal pregnancy. 

24. Draw a labeled sketch of a spermatozoan.

25. What is inhibin? State its functions.

• Sertoli cell or nurse cell is in the stratified epithelium of sertoli cell. They secrete a hormone called inhibin.

• It is involved in the negative feedback control of sperm production.

26. Mention the importance of the position of the testes in humans.

• Testes are in a skin sac called scrotum.

• Scrotum hangs outside the abdominal cavity because viable sperms cannot be produced at normal body temperature.

• Outside the abdominal cavity the temperature is 2-3° C lower than the normal internal body temperature.

• Thus scrotum acts as a thermoregulator for spermatogenesis

27. What is the composition of semen?

• Semen is a milky white fluid with sperms and the seminal plasma.

• Seminal plasma is an alkaline fluid with fructose sugar, ascorbic acid, prostag land in, and vesiculase.

• Vericulase is a coagulating enzyme. It enhances sperm motility.

28. Name the hormones produced from the placenta during pregnancy.

• hCG - human Chorionic Gonadotropin.

• hCS - human Chorionic Somatomammotropin.

• hPL - human Placental Lactogen.

• Oestrogens

• Progesterone

• Relaxin.

29. Define gametogenesis.

• Gametogenesis is the formation of gametes.

• Sperms and ova are produced from primary sex organs like testis and ovary.

• Meiosis plays a significant role in gametogenesis. 

30. Describe the structure of the human ovum with a neat labelled diagram.

• Human ovum is non - cleidoic and alecithal.

• It is microscopic in nature.

• It's cytoplasm is called Ooplasm. Ooplasm contains large nucleus called germinal vesicle.

• It has outer thick coat of follicular cells called corona radiata.

• The middle thick layer is called zona pellucida.

• The inner thin transparent layer is called vitelline membrane.

• Between the vitelline membrane and zona pellucida is a narrow space called perivitelline space.

31. Give a schematic representation of spermatogenesis and oogenesis in humans.

It occurs in the seminiferous tubules.

1. Multiplication phase

• Primoridial germ cells migrate into the testes.

• They become sperm mother cell or spermatogonia

• At puberty, the spermatogonia undergoes mitosis. It continues throughout life.

2. Growth phase

• Spermatogonia go to the central lumen of semeniferous tubule.

They get modified and enlarged into primary spermatocytes, (diploid)

3. Maturation phase

• Primary spermatocytes undergo first meiotic division to form two secondary spermatocytes (haploid)

• The secondary spermatocytes undergo second meiotic division to form 4 haploid spermatids.

4. Spermiogenesis

• Transformation of spermatids into mature spermatozoa.

Oogenesis :

It is the process of development of female gamete ovum (egg) in ovary.

1. Proliferation phase

• Cells in the germinal epithelium to foetal ovary divide by mitosis.

• Thus millions of Oogonia or egg mother cells are formed.

2. Growth phase

• Oogonia form primary Oocytes by meiosis. (prophase I of Meiosis I)

• Primary Oocytes surrounded by single layer of granulosa cells is called primary follicles. Many of them degenerate.

• Primary follicles surrounded by many layers of granulosa cells. These are called secondary follicles.

• A fluid filled space called antrum is formed in secondary follicle. Thus it is transformed into tertiary follicle.

• Primary Oocyte in tertiary follicle grows in size.

3. Maturation pause

• Primary Oocyte completes first meiotic division and forms secondary Oocyte.

• Large haploid secondary Oocyte and first polar body is formed. First polar body disintegrates.

• During fertilisation secondary Oocyte undergoes second meiosis. Thus a large cell ovum and second polar body are formed. Second polar body degenerates.

32. Explain the various phases of the menstrual cycle.

Menstrual cycle.

• It occurs in every 28/29 days. It is from puberty (menarche) to menopause (except during pregnancy).

• The cycle of events from one menstrual period till the next one is called the menstrual cycle.

Phases of menstrual cycle

1. Menstrual phase.

• Progesterone, oestrogen level decreases.

• So uterine endometrial lining and the blood vessels break.

(a) FSH and LH secreted by the anterior pituitary (b) Events in the ovary (c) Overian hormones (d) Events in the endometrium of the uterus

• It results in menstrual flow for 3-5 days.

• It occurs only if the ovum is not fertilised.

• Absence of menstruation indicates pregnancy.

• It is also due to stress, hormonal disorder and anaemia.

2. Follicular Phase or Proliferative Phase (From day 5)

• Secretion of FSH and LH induces the following changes.

• Primary follicle of ovary becomes the mature graffian follicle.

• Endometrium regenerates.

• Follicular development is stimulated.

Oestrogen is secreted by the follicle cells.

3. Ovulatory Phase (about 14th day)

• LH and FSH attain peak level.

• LH surge (increase) induces the rupture of graffian follicle.

• Ovum (secondary Oocyte) is released from the ovary wall into peritoneal cavity. This process is called ovulation.

4. Luteal or Secretory Phase.

• The remaining part of the graafian follicle becomes a transitory endocrine gland. It is called corpus luteum.

• Corpus luteum secretes progesterone. It is needed for the maintenance of endometrium.

• After fertilisation the progesterone helps in implantation, of fertilised ovum.

• Uterine wall secretes nutritive fluid for the foetus. So this phase is called as secretory phase.

• No menstruation occurs during pregnancy.

• In the absence of menstruation, the corpus luteum degenerates. It becomes a scartissue called Corpus albicans.

• It initiates the next cycle.

33. Explain the role of oxytocin and relaxin in parturition and lactation.

Role of Relaxin in parturition and lactation :

• Relaxin is secreted by the placenta. It is found in corpus luteum.

• It relaxes pelvic ligaments.

• It dilates the cervix

• It created continuous powerful contractions

• The amnion ruptures

• The amniotic fluid flows through vagina.

• It is followed by the foetus.

• The placenta and the remains of, the umbilical cord is called 'after birth' It is expelled out after delivery.

Role of oxytocin :

• It causes the Let Down Reflox

• Ejection of milk from the alveoli of mammary glands.

• During lactation, it stimulates the contraction of the empty uterus. Now uterus return to prepregnancy size. 

34. Identify the given image and label its parts marked as a, b, c and d

The given image is 'human ovum'

a. Vitelline Membrane

b. Nucleus.

c. Zona Pellucida.

d. Corona radiata.

35. The following is the illustration of the sequence of ovarian events (a-i) in a human female.

a) Identify the figure that illustrates ovulation and mention the stage of oogenesis it represents.

b) Name the ovarian hormone and the pituitary hormone that have caused the above-mentioned events.

c) Explain the changes that occurs in the uterus simultaneously in anticipation.

d) Write the difference between C and H.

a) Figure 'F' illustrates ovulation. It represents ovulatory phase of Oogenesis.

b) Ovarian hormone - Progesterone, Oestrogen.

Pituitary hormone - FSH (Follicle stimulating hormone) LH (Luteinizing Hormone).

c) Change in uterus

• Endometrium regenerates.

• Fertilisation paves way for the implantation of fertilised ovum.

• uterine wall secretes nutritious fluid for the foetus. So luteal phase is called Secretory phase.

d) C - Secondary Follicle

H - Corpus luteum.

Secondary follicle

• Found in follicular phase (or) proliferative phase.

• It is surrounded by many layers of granu losa cells and a new theca layer

• Later it becomes graafian follicle

Corpus luteum

• Found in luteal phase (or) secretory phase.

• It is a transitory endocrine gland secreting progesterone.

• Later it becomes a scar called corpus albicans.