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A change in the amount of yolk and its distribution in the egg will affect
A
Fertilization
B
Formation of zygote
C
Pattern of cleavage
D
Number of blastomeres produced
Detailed Solution
Yolk is inert, stored food; it slows down or even prevents the division of the cytoplasm in the region where it is concentrated.
Eggs with little, evenly distributed yolk (as in mammals) divide completely: holoblastic, nearly equal cleavage.
Eggs with a moderate amount of yolk concentrated at one pole (as in frogs) show holoblastic but unequal cleavage.
Eggs with a very large amount of yolk (as in birds and reptiles) show meroblastic cleavage, in which only a small disc of cytoplasm divides.
So the amount and distribution of yolk decide the pattern of cleavage; fertilisation and zygote formation are not affected.
Hence it will affect the pattern of cleavage.
Eggs with little, evenly distributed yolk (as in mammals) divide completely: holoblastic, nearly equal cleavage.
Eggs with a moderate amount of yolk concentrated at one pole (as in frogs) show holoblastic but unequal cleavage.
Eggs with a very large amount of yolk (as in birds and reptiles) show meroblastic cleavage, in which only a small disc of cytoplasm divides.
So the amount and distribution of yolk decide the pattern of cleavage; fertilisation and zygote formation are not affected.
Hence it will affect the pattern of cleavage.