Human Reproduction Question 77
77. A change in the amount of yolk and its distribution in the egg will affect
[2009]
(a) pattern of cleavage
(b) number of blastomeres produced
(c) fertilization
(d) formation of zygote
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Answer : a
Hints & Solutions
(a) A change in the amount of yolk and its distribution in the egg will affect pattern of cleavage. The pattern of cleavage is influenced by the amount of yolk in the egg. In eggs with less yolk, cleavages are equal, and the resulting blastomeres are of similar size. If the yolk is localized, such as in frog eggs, then cleavages are unequal, the cells derived from the yolky region (the vegetal pole) are larger than those derived from the region without yolk (the animal pole).
