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Q1. Give a schematic labelled diagram to represent oogenesis (without description).

Solution

Stages in oogenesis      

Q2. Antrum is the cavity of:

• 1) Blastula
• 2) Gastrula
• 3) Ovary
• 4) Graafian follicle

Solution

The characteristic structural unit of the Graafian follicle is the antrum.

Q3. The external sphincter of the urethra shows the presence of which type of cells?

• 1) Smooth muscle
• 2) Ligaments
• 3) Striated muscle
• 4) Connective tissue

Solution

The external sphincter of the urethra shows the presence of striated muscle fibres around its membranous part, while the internal sphincter shows the presence of smooth muscle fibres at its beginning.

Q4. Corpus luteum in mammals occurs in:

• 1) Ovaries and produce progesterone
• 2) Skin and acts as pain receptor
• 3) Brain and connects lobes of cerebrum
• 4) Heart and initiates atrial contraction

Solution

The follicular cells of the empty Graafian follicle form a yellow body called corpus luteum. The corpus luteum secretes progesterone and a smaller amount of estradiol.

Q5. Seminal plasma, the fluid part of semen is contributed by: (i) Seminal vesicle (ii) Prostate (iii) Urethra (iv) Bulbourethral gland

• 1) (ii), (iii) and (iv)
• 2) (i) and (iv)
• 3) (i) and (ii)
• 4) (i), (ii) and (iv)

Solution

Seminal plasma, the fluid part of semen is contributed by seminal vesicle, prostate and bulbourethral gland, which are the parts of male reproductive system. Urethra is a part of the female reproductive system.

Q6. The ploidy level of each polar body formed in oogenesis is

• 1) Diploid
• 2) Without chromosomes
• 3) Haploid
• 4) Triploid

Solution

The polar body is formed during meiosis-II and hence is haploid.

Q7. Cessation of menstrual cycle in female is called:

• 1) Ovulation
• 2) Lactation
• 3) Parturition
• 4) Menopause

Solution

A woman stops producing mature eggs and ceases her menstrual cycle in her late 40s or early 50s. This phase is called menopause.

Q8. Which of the following occurs during spermatocytogenesis?

• 1) Loss of Golgi apparatus
• 2) Loss of water
• 3) Movement of cell organelles to their respective position
• 4) Replication of DNA

Solution

During spermatocytogenesis, the DNA of the cell replicates and the cytoplasm is added to the developing sperm.

Q9. The cell organelle which forms the acrosome of the sperm is

• 1) Vacuole
• 2) Cytoplasm
• 3) Golgi apparatus
• 4) Nucleus

Solution

Some part of the Golgi body forms the acrosome, while the rest of it is lost during sperm formation.

Q10. Which one of the following arises from endoderm?

• 1) Heart
• 2) Eye
• 3) Pigment cells
• 4) Lungs

Solution

Eye, pigment cells and heart arise from the mesoderm.

Q11. The development of the ova completes after

• 1) Secondary oocyte stage
• 2) Fertilisation
• 3) Primary oocyte stage
• 4) Meiosis-I

Solution

An ovum is released after the secondary oocyte stage and its maturation is completed after fertilisation.

Q12. Morula is a developmental stage:

• 1) Between the blastocyst and gastrula
• 2) After the implantation
• 3) Between implantation and parturition
• 4) Between the zygote and blastocyst

Solution

Morula is a developmental stage between the zygote and blastocyst. It consists of 16-32 cells.

Q13. How many sperms will be produced from 10 primary spermatocytes and how many eggs will be produced from 10 primary oocytes?

Solution

10 primary spermatocytes will produce 40 sperms and 10 primary oocytes will produce 10 eggs. 

Q14. A human female reaches menopause around the age of:

• 1) 25 years
• 2) 70 years
• 3) 50 years
• 4) 15 years

Solution

Woman stops producing mature eggs and ceases her menstrual cycle in her late 40s or early 50s.

Q15. A fluid-filled cavity present within blastula is called:

• 1) Blastocoel
• 2) Blastoderm
• 3) Archenteron
• 4) Blastopore

Solution

The fluid absorbed by the trophoblast layer of the blastula collects in a cavity, the blastocoel or blastocyst cavity that separates the trophoblast from the inner cell mass.

Q16. At the end of pregnancy, the hormone relaxin is secreted by

• 1) Uterus
• 2) Corpus albicans
• 3) Corpus luteum
• 4) Vagina

Solution

The corpus luteum secretes two hormones—progesterone during pregnancy and relaxin at the end of pregnancy.

Q17. Uterine contractions during parturition are stimulated by

• 1) Oestrogen
• 2) Oxytocin
• 3) Progesterone
• 4) Relaxin

Solution

During parturition, the posterior pituitary releases oxytocin which stimulates the contraction of the uterine walls.

Q18. Which of the following components is found in a higher concentration in human milk as compared to cow’s milk?

• 1) Phosphorus
• 2) Lactose
• 3) Calcium
• 4) Casein

Solution

Human milk contains a higher concentration of lactose (7 g/100 ml) as compared to cow’s milk (4.8 g/100 ml).

Q19. What is parturition? Which hormones are involved in it?

Solution

Parturition is the act of expelling the fully developed young one (foetus) from the mother's uterus at the end of gestation period. Oxytocin and relaxin hormones are involved in parturition.

Q20. The inability of a male to achieve or hold onto an erection for complete copulation is known as

• 1) Prostatomegaly
• 2) Impotence
• 3) Sterility
• 4) Prostatic hypertrophy

Solution

The inability of a male to achieve or hold onto an erection for complete copulation is known as impotence. Sterility is the inability of the male sperm to fertilise the ovum. Prostatic hypertrophy or prostatomegaly is the enlargement of the prostate gland.

Q21. What is the amount of milk produced by a lactating mother per day?

• 1) 2-4 litres
• 2) 1-2 litres
• 3) 0.5-1 litre
• 4) 1-5 litres

Solution

A lactating mother produces about 1-2 litres of milk per day.

Q22. Spermiation is the process of the release of sperms from:

• 1) Epididymis
• 2) Seminiferous tubules
• 3) Prostate gland
• 4) Vas deferens

Solution

The process of release of spermatozoa or sperms from Sertoli cells into the cavity of seminiferous tubules is called spermiation.

Q23. The complete development of a sperm in the male reproductive system takes how much time?

• 1) 2 months
• 2) 5 months
• 3) 1 month
• 4) 10 days

Solution

The complete development of a sperm in the male reproductive system takes about 2 months.

Q24. Cervix is a part:

• 1) Of fallopian tube
• 2) Between uterus and vagina
• 3) Of kidney
• 4) Of epididymis

Solution

The cervix communicates above with the body of the uterus by an aperture, the internal os and with the vagina below by an opening, the external os.

Q25. Which stage of the cell cycle is skipped during cleavage of the zygote?

• 1) Only G1
• 2) S
• 3) Both G1 and G2
• 4) M

Solution

During cleavage of the zygote during embryonic development, the cells of the developing embryo undergo mitotic divisions and undergo only the M and S phases of the cell cycle. The cells entirely skip the G1 and G2 phases of the cell cycle.

Q26. The septa of the testis is formed by the inward growth of

• 1) Tunica vasculosa
• 2) Spermatic cords
• 3) Tunica vaginalis
• 4) Tunica albuginea

Solution

The tunica albuginea shows inward growth in the testis, called septa, which divides each testis into 200 to 300 lobules.

Q27. Give the function of: (a) Corpus luteum (b) Endometrium

Solution

(a) Corpus luteum: It secretes progesterone which prepares endometrium of the uterus for implantation and normal development of the foetus. (b) Endometrium: It undergoes cyclic changes during menstrual cycle and prepares itself for implantation of the blastocyst.

Q28. Differentiate between menarche and menopause.

Solution

The beginning of first menstrual cycle at puberty in human females is called menarche. The cessation of menstrual cycle in women around 50 years of age is called menopause.

Q29. The middle portion of the epididymis is known as

• 1) Caput epididymis
• 2) Corpus epididymis
• 3) Cauda epididymis
• 4) Caustic epididymis

Solution

The epididymis is divided into three regions—the upper, wider portion known as the caput epididymis, the middle narrow corpus epididymis and the lower cauda epididymis.

Q30. Crossing over in gamete formation occurs during

• 1) Meiosis-I
• 2) Mitosis
• 3) Meiosis-II
• 4) Cytokinesis

Solution

Meiosis-I is associated with crossing over of homologous chromatids, which introduces variations in the chromosomes and the gametes thus formed.

Q31. The plasma membrane of the ovum is known as

• 1) Ooplasm
• 2) Oolemma
• 3) Alecithal
• 4) Zona pellucida

Solution

The plasma membrane of the ovum is known as the oolemma. The cytoplasm is known as the ooplasm. Alecithal is the condition of lacking a yolk sac in the ovum. Zona pellucida is the inner, transparent, non-cellular egg coat of the ovum.

Q32. The receptors found on the zona pellucida of the ova which recognise and bind to the sperm are

• 1) ZP4
• 2) ZP3
• 3) ZP1
• 4) ZP2

Solution

ZP3 receptors are glycoproteins found on the zona pellucida which recognise and bind the sperms and induce the acrosome to release hydrolytic enzymes.

Q33. Why are menstrual cycles absent during pregnancy?

Solution

When pregnancy occurs, high levels of progesterone and estrogens suppress the gonadotrophin (FSH). The latter is required for the development of new follicles. Thus, new menstrual cycle cannot be initiated as long as FSH secretion is suppressed. So, menstrual cycles are absent during pregnancy

Q34. Draw a labelled section view of seminiferous tubule of a human male.

Solution

Section view of seminiferous tubule of a human male      

Q35. Where are the Leydig cells present? What is their role in reproduction?

Solution

Leydig cells are small groups of large, polygonal cells that lie in the connective tissue present between the seminiferous tubules. They secrete androgens, the male sex hormone (e.g. testosterone) into the blood.

Q36. In which part of sperm, mitochondria are present?

• 1) Head
• 2) Neck
• 3) Tail
• 4) Middle piece

Solution

The middle piece contains many mitochondria tightly coiled round the axial filament. The mitochondria provide energy for the movement for sperm in the female genital tract.

Q37. Where are fimbriae present in human female reproductive system? Give their function.

Solution

The funnel-shaped proximal part of the fallopian tube is called infundibulum. Its margin bears motile, finger-like processes called fimbriae. The fimbriae bear cilia that beat towards the operature (called ostium) to direct the release of egg (from ovary) into the infundibulum.

Q38. 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?

Solution

(a) The figure represents the blastula stage of human embryo (also called blastocyst). (b) The ‘a’ in the figure is trophoblast (trophoectoderm). The trophoblast gives rise to extra-embryonic membranes for protection and nourishment of the embryo. (c) The inner cell mass (after implantation in the uterus) gives rise to three germ layers (ectoderm, mesoderm and endoderm) or simply embryo. (d) Inner cell mass (embryonal knob) represents the stem cells.

Q39. Vasocongestion in the penis leads to

• 1) Erection
• 2) Release of sperms
• 3) Rupture of arterial walls in the penis
• 4) Subsidence of erection

Solution

The filling up of the sinuses of the penis with blood from the arteries is known as vasocongestion. This builds up the hydraulic pressure in the penis leading to the erection of the penis.

Q40. In the ovum, meiosis-II is completed after

• 1) Entry of the sperm
• 2) Binding of the sperm to ZP3
• 3) Copulation
• 4) Release of progesterone by the corpus luteum

Solution

The entry of the sperm in the ovum stimulates the egg to resume and complete its suspended meiosis-II division, thus forming a mature egg cell.

Q41. Draw a labelled diagram of the reproductive system in a human female.

Solution

Reproductive system in a human female    

Q42. Given below is an incomplete flowchart showing the influence of hormone on gametogenesis in males. Observe the flowchart carefully and fill in the blank A, B, C and D.       

Solution

A: Testosterone; B: Spermatogenesis; C: Sertoli cells; D: Spermiogenesis

Q43. Draw a labelled diagram of longitudinal section of a mammalian ovary.

Solution

Longitudinal section of a mammalian ovary        

Q44. Three of the steps of neuro-endocrine mechanism in respect of parturition are mentioned below. Write the missing steps in proper sequence. (a) Signals originate from fully developed foetus and placenta. (b) _____________. (c) _____________. (d) Oxytocin causes strong uterine contraction. (e) Uterine contraction stimulates further secretion of oxytocin. (f) _____________.  

Solution

(b) Foetal ejection reflex (c) The reflex triggers release of oxytocin (f) Expulsion of the baby out through the birth canal.

Q45. How long do spermatozoa survive in the female reproductive tract? 

• 1) 1-3 days
• 2) 5 days
• 3) 1 day
• 4) 1-2 hours

Solution

Spermatozoa once released into the female reproductive tract can survive for about 1-3 days.

Q46. ICSH is secreted by

• 1) Thyroid
• 2) Hypothalamus
• 3) Anterior pituitary
• 4) Posterior pituitary

Solution

ICSH is secreted by the anterior pituitary.

Q47. Describe the functions of human placenta.

Solution

Functions of human placenta: 1. Nutritive organ: Food materials pass from the mother’s blood into the foetal blood through the placenta. 2. Digestive organ: The trophoblast of the placenta digests proteins before passing them into foetal blood. 3. Respiratory organ: Oxygen diffuses from the maternal blood into foetal blood through the placenta. Carbon dioxide diffuses from the foetal blood into the maternal blood also through the placenta for elimination by the mother’s lungs. 4. Excretory organ: Nitrogenous wastes pass from the foetal blood into the maternal blood through the placenta for elimination by mother’s kidneys. 5. Endocrine organ: Placenta secretes (hCG), estrogen, progesterone and human placental lactogen. 6. Storage organ: The placenta stores glycogen for the foetus before liver is formed. 7. Barrier: Many substances pass from the mother to the foetus via placenta and cause abnormal development in the developing foetus.

Q48. Name the muscular and the glandular layers of human uterus. Which one of these layers undergoes cyclic changes during menstrual cycle? Name the hormone essential for the maintenance of this layer.

Solution

(i) The muscular layer of human uterus is called myometrium and the glandular layer is called endometrium. (ii) Endometrium undergoes cyclic changes during the menstrual cycle. (iii) Progesterone is essential for the maintenance of endometrium.

Q49. Production of sperms requires low temperature. How is it accomplished in the human body? 

Solution

The testis descend below the abdominal cavity at maturity in males. This helps in regulating temperature which is necessary for the production of sperms.

Q50. What is meant by LH surge? Write the role of LH.

Solution

Rapid secretion of LH leading to its maximum level during the mid-cycle is called LH surge. It induces rupture of Graafian follicle and thereby the release of ovum (ovulation).

Q51. Draw a labelled diagram of the microscopic structure of a human sperm.

Solution

Microscopic structure of a human sperm        

Q52. Failure of testes to descend into scrotal sacs leads to sterility. Why?

Solution

High temperature of the abdomen kills the spermatogenic tissue of the testes. Thus, no sperms are formed. Hence, failure of testes to descend into scrotal sacs leads to sterility.

Q53. Study the flow chart given below. Name the hormones involved at each stage and explain their functions.   Hypothalamus   Pituitary   Ovary   Pregnancy  

Solution

Hypothalamus: Hypothalamus releases gonadotrophin releasing hormone (GnRH) which stimulates the anterior pituitary gland to secrete FSH, LH and progesterone.   Pituitary: Anterior pituitary gland secretes FSH to stimulate the growth of Graafian follicle, maturation of ovum and secretion of estrogen by follicle cells. It also secretes LH which stimulates release of ovum, formation of corpus luteum in the empty follicle and secretion of progesterone from the corpus luteum.   Ovary: The follicles in the ovary secrete estrogen which brings about growth and maturation of the reproductive tract and development of accessory sex characters.    Pregnancy: Progesterone suspends ovulation during pregnancy, maintains foetal connection with the uterine wall and controls development of foetus in the uterus. Estrogen and progesterone stimulate the development of mammary glands during pregnancy. 

Q54. Placenta acts as an endocrine tissue. Justify

Solution

Placenta secretes hormones such as human chorionic gonadotrophic (hCG), estrogen, progesterone and human placental lactogen. So, placenta is regarded as an endocrine tissue.

Q55. ‘Each and every coitus does not result in fertilisation and pregnancy’. Justify the statement.

Solution

It is important that the ovum and sperm reach simultaneously to the ampullary-isthmic junction. As most of the sperms and ova fail to do so, each and every coitus does not result in fertilisation and pregnancy.