Zoology XII+ - Human Reproduction 12

Question : 1

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Biologically a woman is said to be pregnant after

Options:

	Coitus
	Fertilization
	Implantation
	After formation of basic structures of developing embryo

Solution :

(3)

 

Only successful implantation makes the female pregnant.

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Question : 2

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During cleavage there is

Options:

	Appreciable increase in mass of protoplasm
	Increase in size of cells
	Marked increase in the DNA containing chromosomal material
	Increase in protoplasm and DNA

Solution :

(3)

 

Each cleavage results in formation of small blastomeres so protoplasmic

content decreases but DNA content increases.

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Question : 3

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If trophoblast layer failed to form a part of mammalian embryo, which of the following structure would not develop?

Options:

	Embryo proper
	Foetal part of placenta
	Uterine part of placenta
	Blastocoel

Solution :

(2)

 

Trophoblast makes foetal part of placenta and extra embryonic membrane.

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Question : 4

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The type of blastula present in mammals is

Options:

	Coeloblastula
	Amphiblastula
	Stereoblastula
	Discoblastula

Solution :

(1)

 

Stereoblastula is solid blastula, characteristic of coelenterates; Amphiblastula is larva of sponges; Discoblastula is a character of birds; Coeloblastula exists in mammals having blastocoels.

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Question : 5

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If zona pellucida is digested during morula stage in fallopian tube then which of the following condition is likely to happen?

Options:

	Mobility is affected
	Cleavage is affected
	Corona radiata behaves like zona pellucida
	It leads to ectopic pregnancy

Solution :

(4)

 

If zona pellucida is digested in fallopian tube, the cells of Rauber will expose and get attached to the surface.

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Question : 6

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Identify the human development stage shown below as well as the related right place of its occurrence in a normal pregnant female.

             

                                    

           Developmental                             Site of stage occurrence

 

(1)      Early morula                 –         Ampula of fallopian tube

(2)      Late morula                  –         End part of fallopian tube

(3)      Blastula                         –         Isthmus of fallopian tube

(4)      Blastocyst                     –         Uterine wall

Options:

	1
	2
	3
	4

Solution :

(4)

 

Blastocyst is identified by the presence of blastocoel and is implanted in uterine wall.

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Question : 7

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Which is the correct sequence of cleavage in human zygote after fertilization?

 

               1^st                      2^nd                   3^rd

 

(1)     Meridional         Meridional      Equatorial

(2)     Meridional         Equatorial      Vertical

(3)     Equatorial         Meridional      Equatorial

(4)     Meridional         Horizontal      Meridional

Options:

	1
	2
	3
	4

Solution :

(1)

 

1^st and 2^nd cleavage are meridional and 3^rd is equatorial in human zygote.

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Question : 8

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Implantation of blastocyst takes place

Options:

	16 hours after fertilisation
	36 hours after fertilisation
	Just after fertilisation
	One week after fertilization

Solution :

(4)

 

Implantation occurs on 7^th day after fertilization.

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Question : 9

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Find the incorrect statement

Options:

	Morula is a solid ball of cells showing resemblance to a mulberry
	The embryo proper develops from the inner cell mass in course of development
	Cleavage continues till blastocyst formation
	First cleavage in humans starts after 60 hours of fertilization

Solution :

(4)

 

First cleavage in humans starts after 30 hours of fertilization.

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Question : 10

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Which of the following provides nutrition to the embryo?

Options:

	Zona pellucida
	Corona radiata
	Trophoectoderm
	Amniotic fluid

Solution :

(3)

 

Trophoectoderm/Trophoblast makes placenta that provides nourishment to developing embryo.