OBJECTIVE LIFE SCIENCE
DEVELOPMENTAL BIOLOGY
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Question
[CLICK ON ANY CHOICE TO KNOW THE RIGHT ANSWER]
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In chick the cleavage divisions are restricted to ____
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Blastocentre
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Blastula
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Blastodisc
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Blastoderm
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Explanation:
Detailed explanation-1: –Cleavage in chicks are mostly meroblastic and also known as discoidal as it is restricted to the blastodisc, which is a small circular structure present on the yolk of the egg which restricts the division to a small part of the nucleus and cytoplasm of the egg.
Detailed explanation-2: -Meroblastic cleavage occurs in macrolecithal eggs. It is an incomplete cleavage. Due to the abundant yolk present in the egg, unequal mitotic division occurs.
Detailed explanation-3: -Yolk exerts an intense preventing influence on the process of cleavage and the mechanics of moving the germ layers in their final positions. It delayed the process of mitosis, and even deters it from extending into the over dense regions.
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