Human Reproduction Question 83

83. The correct sequence in the process of development of human embryo is

[1998]

(a) fertilisation-zygote-cleavage - morulablastula-gastrula

(b) fertilisation - cleavage - morula-zygoteblastula-gastrula

(c) fertilisation-zygote-blastula - morulacleavage-gastrula

(d) cleavage-zygote-fertilisation-morulablastula-gastrula

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Answer : a

Hints & Solutions

(a) Fusion of male and female gamete produces a zygote. Repeated division of the zygote is called cleavage forming a solid morula. After further division and rearrangement a fluid filled cavity surrounded by blastomeres - blastula is formed. The appearance of germ layers mark the gastrula.