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Explore popular questions from Reproduction for NEET. This collection covers Reproduction previous year NEET questions hand picked by experienced teachers.

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Chemistry

Physics

Biology

Reproduction

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Q 1. The middle piece of the sperm contains

A

proteins

mitochondria

C

centriole

D

nucleus.

Explanation

The sperm consists, of head, neck, middlepiece and tail. The middle piece of human spermcontains the mitochondria coiled around the axialfilament called mitochondrial spiral. They provideenergy for the movement of the sperm.

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Q 2. In the human female, menstruation can be deferred by the administration of

A

combination of {tex} \mathrm { FSH } {/tex} and {tex} \mathrm { LH } {/tex}

combination of estrogen and progesterone

C

FSH only

D

LH only

Explanation

{tex} ( b ) {/tex}

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Q 3. Grey crescent is the area

A

at the point of entry of sperm into ovum

just opposite to the site of entry of sperminto ovum

C

at the animal pole

D

at the vegetal pole.

Explanation

Grey crescent is the area just opposite tothe site of entry of sperm into ovum. It marks thefuture dorsal side of the embryo.

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Q 4. The anthesis is a phenomenon, which refers to

A

development of anthers

opening of flower bud

C

stigma receptórs

D

all of these.

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Q 5. Blastopore is

A

opening of neural tube

opening of gastrocoel

C

future anterior end of embryo

D

found in blastula.

Explanation

Blastopore is the opening by which the cavity of the gastrula (gastrocoel), communicates with the exterior. It is formed as a result of invagination of endoderm during embryonic development. During maturation of some animals it evolves into the anus or the mouth; in others it is covered over and contributesto the canal joining the primitive gut with the cavity ofthe neural tube.

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Q 6. In the 28 day human ovarian cycle, the ovulation takes place typically on

day 14 of the cycle

B

day 28 of the cycle

C

day 1 of the cycle

D

day 5 of the cycle.

Explanation

: Ovulation is the releasing of egg by ruptured graafian follicle. The wall of graafian follicle is ruptured by sudden increase in the level of luteinising hormone. The length of menstruation cycle is 28 days (average) from the start of one menstruation period to the start of the next. At about 14 th day of the cycle, the distended follicle ruptures and the ovum is extruded into the Fallopian tube.

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Q 7. What is true for cleavage?

A

Size of embryo increases.

Size of cells decreases.

C

Size of cells increases.

D

Size of embryo decreases.

Explanation

During cleavage, the zygote divides repeatedly to convert the large cytoplasmic mass intoa large number of small blastomeres. It involves cell division without growth in size because cells continueto be retained within the zona pellucida. However,cell size decreases during cleavage.

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Q 8. Vasa efferentia are the ductules leading from

A

testicular lobules to rete testis

rete testis to vas deferens

C

vas deferens to epididymis

D

epididymis to urethra.

Explanation

The seminiferous tubules are closed at one end but on the other side they join to a network the rete testis from where fine ciliated ductules, the vasa efferentia arise. Cilia help in conducting sperms. The rete testis is a network of tubules conducting sperm from the seminiferous tubules of the testis to the vasa efferentia.

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Q 9. Which one of the following is not the functionof placenta?

A

Facilitates removal of carbon dioxide andwaste material from embryo

Secretes oxytocin during parturition

C

Facilitates supply of oxygen and nutrientsto embryo

D

Secretes estrogen

Explanation

Parturition is induced by a complexneuroendocrine mechanism. The signals forparturition originate from the fully developed foetusand the placenta which induce mild uterinecontractions called foetal ejection reflex. This triggersrelease of oxytocin from the maternal pituitary.
Oxytocin acts on the uterine muscle and causesstronger uterine contractions, which in turn stimulatesfurther secretion of oxytocin. The stimulatory reflexbetween the uterine contraction and oxytocinsecretion continues resulting in stronger and strongercontractions. This lead to expulsion of the baby outof the uterus through the birth canal.

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Q 10. Fertilisation in humans is practically feasibleonly if

A

the ovum and sperms are transported simultaneously to ampullary-isthmic junction of the cervix

B

the sperms are transported into cervixwithin 48 hrs of release of ovum in uterus

C

the sperms are transported into vagina just after the release of ovum in Fallopian tube

the ovum and sperms are transported simultaneously to ampullary-isthmic junction of the Fallopian tube.

Explanation

The fusion of a haploid male gamete (sperm)and a haploid female gamete (ovum) to form a diploidzygote is called fertilisation. In human beings, it takesplace in the ampullary isthmic junction of the oviduct(Fallopian tube).

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Q 11. The figure shows a section of human ovary.Select the option which gives the correctidentification of either A or B with function/characteristic.

B- Corpus luteum {tex} - {/tex} Secretes progesterone

B

A- Tertiary follicle - Forms Graafian follicle

C

B- Corpus luteum - Secretes estrogen

D

A- Primary oocyte {tex} - {/tex} It is in the prophase Iof the meiotic division

Explanation

The zona granulosa and theca cells ofGraafian follicle remaining in the ovary afterovulation and some surrounding capillaries andconnective tissue evolve into the corpus luteum (atemporary endocrine gland). The corpus luteumproduces progesterone and, in the event offertilization, provides the required progesterone untilthe placenta is formed. In the absence of fertilization,the life span of the corpus luteum is 14 days. It thendegenerates into a corpus albicans, which is mainly ascar tissue.

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Q 12. Blastopore is the pore of

archenteron

B

blastocoel

C

coelom

D

alimentary canal.

Explanation

Archenteron is known as the primitive gut that forms during gastrulation in the developing blastula. It develops into the digestive tract of an animal. The open end of the archenteron is called blastopore.

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Q 13. The shared terminal duct of the reproductive and urinary system in the human male is

urethra

B

ureter

C

vas deferens

D

vasa efferentia.

Explanation

Urethra is the urinary duct which originates from the neck of urinary bladder and opens to the exterior at the tip of penis in males. It is a common pathway for passage of urine and semen.

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Q 14. The secretory phase in the human menstrualcycle is also called

A

luteal phase and lasts for about 6 days

B

follicular phase and lasts for about 6 days

Luteal phase and lasts for about 13 days

D

follicular phase and lasts for about 13days.

Explanation

After ovulation which occurs in the middleof menstrual cycle, enypty Graafian follicle continuesgrowth under the influence of LH. The follicular cellsare converted into lutein cells by deposition ofyellowish lipid inclusions. The phenomenon is calledluteinization. The ruptured Graafian follicle is nowcalled corpus luteum. It secretes hormones, mainlyprogesterone and small quantity of estrogen. Both LHand progesterone help in further growth and
thickening of endometrium. The major change is thatthe endometrial glands become secretory. The uterinewall becomes ready for nourishing and anchoringblastocyst if fertilization takes place. Hence, thisphase of menstrual cycle is called luteal or secretoryphase. The phase lasts for about 13 days {tex} i . e .15 - 28 {/tex}days of 28 days menstrual cycle.

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Q 15. Which one of the following statements aboutmorula in humans is correct?

It has almost equal quantity of cytoplasmas an uncleaved zygote but much moreDNA.

B

It has far less cytoplasm as well as lessDNA than in an uncleaved zygote.

C

It has more or less equal quantity ofcytoplasm and DNA as in uncleavedzygote.

D

it has more cytoplasm and more DNA thanan uncleaved zygote.

Explanation

A morula is an embryo at an early stage of embryonic development, consisting of cells (calledblastomeres) in a solid ball contained within the zonapellucida. The morula is produced by embryonic cleavage, the rapid division of the zygote. The increase in number of cells does not change the size of the original mass. The divisions are rapid because there
is no net growth of the embryo-the cell cycle alternates between DNA replication and mitosis. In the absence of growth, the cell number in the embryo increases while the cell size decreases. Thus, it has almost equal quantity of cytoplasm as an uncleaved zygote but much more DNA.

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Q 16. Which one of the following statements is false in respect of viability of mammalian sperm?

Sperm is viable for only up to 24 hours

B

Survival of sperm depends on the pH of the medium and is more active in alkaline medium.

C

Viability of sperm is determined by its motility.

D

Sperms must be concentrated in a thick suspension.

Explanation

Sperms remain viable for 48 hours to 72 hours.

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Q 17. Cells become variable in morphology andfunction in different regions of the embryo.The process is

differentiation

B

metamorphosis

C

organisation

D

rearrangement.

Explanation

Differentiation are the changes from simpleto more complex forms undergone by developing tissues and organs so that they become specializedfor particular functions. Differentiation occurs during embryonic development and regeneration.

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Q 18. Identify the human developmental stage shown below as well as the related right place ofits occurrence in a normal pregnant woman, and select the right option for the two,together.


A

Developmental stage - Late morula
Site of occurrence - Middle part of fallopian tube

B

Developmental stage - Blastula
Site of occurrence - End part of Fallopian tube

Developmental stage - Blastocyst
Site of occurrence - Uterine wall

D

Developmental stage - 8 -celled morula
Site of occurrence - Starting point of Fallopian tube

Explanation

After fertilization, zygote undergoes rapid mitotic divisions, called cleavage, which is characterized by absence of growth of daughter cells. This leads to the conversion of single celled zygote into a multicellular structure called blastocyst or blastula. Implantation or embedding of zygote into endometrium of uterus occurs in blastocyst stage. The various stages in the journey of a fertilized egg from fertilization in the Fallopian tube to the implantation site in the uterus is illustrated in the given figure.

Blastocyst comes in contact with the endometrium inthe region of embryonal knob or embryonic disc. Itadheres to the same. The surface cells of trophoblastsecrete lytic enzymes which cause corrosion ofendometrial lining. They also give rise to finger-likeoutgrowths called chorionic villi. Chorionic villi anduterine tissue become interdigitated. Villi not onlyhelp in fixation but also absorption of nourishment.

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Q 19. In our society women are blamed for producing female children. Choose the correct answer for the sex-determination in humans.

A

Due to some defect like aspermia in man

Due to the genetic make up of the particular sperm which fertilizes the egg

C

Due to the genetic make up of the egg

D

Due to some defect in the women

Explanation

Establishment of sex through differential development in an individual at an early stage of lifeis called sex determination. It is determined at the time of fertilization and is also called as syngametic sex determination. The female is homomorphic (isomorphic) possessing two similar sex chromosomes, XX and the male is heteromorphic possessing one X chromosome similar to that of female and one shorter and morphologically different Y chromosome. The female is said to be homogametic (produces similar eggs) and the male heterogametic (produces two types of sperms i.e., X or Y). Sex is determined at the time of fertilization by the kind of sperm (X or Y) that fuses with the ovum (X).

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Q 20. Menstrual flow occurs due to lack of

A

oxytocin

B

vasopressin

progesterone

D

FSH.

Explanation

The corpus luteum secretes large amountsof progesterone which is essential for maintenance of the endometrium. Such as endometrium is necessary for implantation of the fertilized ovum and other events of pregnancy. In the absence of fertilization, the corpus luteum degenerates. This  causes disintegration of the endometrium leading to menstruation. The menstrual flow results due to breakdown of endometrial lining of the uterus and its blood vessels which forms liquid that comes out through vagina.

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Q 21. Which set is similar?

Corpus luteum - Graafian follicles

B

Sebum - Sweat

C

Bundle of His - Pace maker

D

Vitamin {tex} B _ { 7 } - {/tex} Niacin

Explanation

A mature ovarian follicle is called Graafianfollicle. It contains follicular cells, an antrum, and anoocyte. After ovulation, the empty Graafian follicleshows deposition of leutin and forms corpus luteumthat ultimately degenerates.

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Q 22. If for some reason, the vasa efferentia in the human reproductive system get blocked, the gametes will not be transported from

testes to epididymis

B

epididymis to vas deferens

C

ovary to uterus

D

vagina to uterus.

Explanation

The male sex accessory ducts include retetestis, vasa efferentia, epididymis and vas deferens.The seminiferous tubules of the testis open into thevasa efferentia through rete testis. The vasa efferentia leave the testis and open into each testis. So if vasa the posterior surface of each testis. So if vasaefferentia gets blocked, the gametes will not be transported from testes to epididymis.

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Q 23. What is true about cleavage in the fertilized egg in humans?

It starts while the egg is in Fallopian tube.

B

It starts when the egg reaches uterus.

C

It is meroblastic.

D

It is identical to the normal mitosis.

Explanation

Cleavage is a series of rapid mitotic divisionsof the zygote which convert the single celled zygote into a multicellular structure called blastula(blastocyst).
About thirty hours after fertilization, the newly formed zygote divides into two cells, the blastomeres, in the upper portion of the Fallopian tube. This is the firstcleavage. The next division occurs within forty hours after fertilization. The third division occurs about three days after fertilization. During these early cleavages, the young embryo is slowly moving down the Fallopian tube towards the uterus. At the end of fourth day, the embryo reaches the uterus. It has thirtytwo cells.

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Q 24. ectoderm

ectoderm

B

mesoderm

C

endoderm

D

ectoderm and mesoderm.

Explanation

Ectoderm, mesoderm and endoderm are thethree germ layers that give rise to the specific tissues,
organs and organ-systems. Ectoderm gives rise toconjunctiva, cornea, lens of eye, muscles of iris,vitreous humour, retina, lacrimal gland along withother parts of the body.

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Q 25. Sertoli cells are regulated by the pituitary hormone known as

A

{tex} \mathrm { LH } {/tex}

FSH

C

GH

D

prolactin.

Explanation

Sertoli cells are present in the germinal epithelium of the seminiferous tubules. These cells nourish the developing sperms. These cells differentiate spermatogonia into sperms. They are under the influence of FSH released by anteriorpituitary gland.