Question

Beginning with a cell that just fertilized ( 1 cell ) how many times must it divide to become a 64 cell blastomere ?

Answer 1

A cell that just fertilized has to divide 6 times to form a 64 cell blastomere.

Explanation:

Human reproduction begins with the fusion of male gamete sperm and female gamete ovum. The fusion of sperm and ovum forms the zygote that is diploid. The zygote then undergoes mitotic division to develop into embryo.  

The zygote first divides into two and the two individual cells divide again to form four individual cells and so on. Thus the number of cells after each division can be represented by the equation $2^n$  where n is the number of divisions.  in the question it is given that the blastomere has 64 cells.

$2^n=64$  

n=6

This means that the fertilized cell has to divide 6 times to develop into 64-celled blastomere.