NEET2010ZoologyHuman ReproductionActual
Which one of the following statements about morula in humans is correct?
Options
- AIt has almost equal quantity of cytoplasm as an uncleaved zygote but much more DNA
- BIt has far less cytoplasm as well as less DNA than in an uncleaved zygote
- CIt has more or less equal quantity of cytoplasm and DNA as in uncleaved zygote
- DIt has more cytoplasm and more DNA than an uncleaved zygote
Correct answer
A. It has almost equal quantity of cytoplasm as an uncleaved zygote but much more DNA
Step-by-step solution
At about 30 to 36 hours of fertilisation, the zygote moves through the isthmus of oviduct to uterus and divides mitotically by a process called cleavage which results into two smaller cells called blastomeres. A second cleavage occurs which results in the formation of 4 cells. Cleavage continues to occur and results in a solid ball of cells i.e. morula having 16 cells (occasionally 32). Since the divisions are mitotic, therefore the size of morula is same as that of zygote because with each cleavage division, numbe