Question

Which of the following statement is correct about human embryonic development?

• A. Cleavage divisions bring about considerable increase in mass of protoplasm
• B. In the second division, one of the two blastomeres usually divides a little sooner than the second
• C. With more cleavage divisions the resultant blastomeres become larger and larger
• D. Cleavage divisions result in hollow ball of cells called morula

Answer 1

Answer: (B)

In the second division, one of the two blastomeres usually divides a little sooner than the second

After fertilization, the zygote is formed which is a single cell structure. This zygote undergoes rapid mitotic division to form 8-16 cell structure which is known as the morula.

In the zygote, the first cleavage forms two cells known as the blastomeres. They are slightly unequal in size and so on the second and third cleavage also takes place forming 4 and then 8 blastomeres.

So, the correct option is ' In the second division, one of the two blastomeres usually divides a little sooner than the second.'