Zoology XII+ - Human Reproduction 13

Question : 1

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After implantation, inner cell mass get differentiated into three germ layers that give rise to all the tissues/organs in adult. Find the incorrect combination of organ/s and germ layer involved in its formation.

 

      Organs/System                      Germ layer
(1)  Skeleton, muscles                   Mesoderm
(2)  Notochord, nerve cord               Ectoderm
(3)  Liver, pancreas                         Endoderm
(4)  Pineal gland, hypothalamus      Ectoderm

Options:

	1
	2
	3
	4

Solution :

(2)

Notochord is mesodermal in origin.

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Question : 2

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Which of the following embryonic germinal layer is formed from trophoblast?

Options:

	Ectoderm
	Mesoderm
	Endoderm
	None of these

Solution :

(4)

 

Trophoblast makes placenta and extra embryonic membranes.

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Question : 3

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Gastrulation is basically a morphogenetic movement of blastomeres. Termination of gastrulation is indicated by

Options:

	Obliteration of archenteron
	Obliteration of blastocoel
	Closure of blastopore
	Closure of neural tube

Solution :

(2)

 

Gastrulation process is considered to be complete when blastocoels obliterates and new cavity archenteron is formed.

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Question : 4

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If gastrulation involve migration and spreading of micromeres over the embryo, the type of morphogenetic movement is

Options:

	Epiboly
	Invagination
	Involution
	Ingression

Solution :

(1)

 

Invagination results in formation of a slit that later on gives rise to blastopore. Involution is curling in of mesoderm cells towards anterior side along the roof of blastocoels; Ingression is the migration of individual vegetal cells to the interior of the embryo.

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Question : 5

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In human embryonic development which of the following events takes place by the end of the second month of pregnancy?

Options:

	Most of the major organ systems are formed
	Limbs and digits are formed
	Eyelids separate and eyelashes are formed
	First movement of baby is observed

Solution :

(2)

 

All major organs are formed by the end of 1^st trimester; 1^st movement is

observed during fifth month; eyelids open and eyelashes are formed by the

end of 2^nd trimester.

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Question : 6

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The first sign of growing foetus appear after listening heart sound carefully through the stethoscope. This sound can be noticed by the

Options:

	End of first month
	End of first trimester
	End of second month
	End of second trimester

Solution :

(1)

 

Heart is formed by the end of 4^th week of pregnancy.

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Question : 7

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Blastopore is formed in

Options:

	Gastrula – opening of archenteron
	Blastula – opening of blastocoel
	Blastula – opening of archenteron
	Gastrula – opening of blastocoel

Solution :

(1)

 

Blastopore is formed in gastrula stage and is an opening of archenteron.

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Question : 8

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The earliest haemopoietic site of a developing foetus is

Options:

	Liver
	Spleen
	Yolk sac
	Allantois

Solution :

(3)

 

Yolk sac synthesise blood for early 2-3 weeks of development.

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Question : 9

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Following is the diagrammatic representation of foetus surrounded by different extra embryonic membranes. Find the exact marking of these membranes along with the appropriate function performed by it.

 

                                  

Options:

	A – Amnion – Prevent sticking of embryo to uterine wall B – Yolk sac – Provide nourishment to developing embryo
	A – Chorion – Surrounds the whole embryonic system of embryo B – Allantois – Act as embryonic urinary bladder
	C – Yolk sac – Synthesis of blood and blood vessels D – Amnion – Protect embryo from mechanical shock
	C – Allantois – Formation of blood vessels D – Chorion – Make chorionic villi for placenta formation

Solution :

(2)

 

A – Chorion

B – Allantois

C – Yolk sac

D – Amnion

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Question : 10

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Gestation period in humans is ________ when counted from day of conception to delivery.

Options:

	266 days
	280 days
	38 weeks
	Both (1) & (3)

Solution :

(4)

 

Gestation period is 280 days when counted from last menstrual cycle to delivery.