Question
Biology Question on human reproduction
In an egg, the type of cleavage is determined by
A
the amount and distribution of yolk
B
the number of egg membranes
C
the shape and size of the sperm
D
the size and location of the nucleus.
Answer
the amount and distribution of yolk
Explanation
Solution
The amount of yolk and how it is distributed determines the type of cleavage. On this basis cleavage is of two types: (a) Holoblastic - where the segmentation line passes through the entire egg. It occurs in alecithal (without yolk), microlecithal (with very little amount of yolk) and mesolecithal (little amount of yolk) egg. (b) Meroblastic - where segmentation line does not pass through the egg and remained confined to a part of the egg. It occurs in megalecithal (large amount of yolk) egg.