Which one of the following statements with regard to embryonic development in humans is correct?
Cleavage divisions bring about considerable increase in the mass of protoplasm
In the second cleavage division, one of the two blastomeres usually divides a little sooner than the second
With more cleavage divisions, the resultant blastomeres become larger and larger
Cleavage division results in a hollow ball of cells called morula
During the development of embryo which of the following occur first
$A$ : Placenta is connected to the embryo through an umbilical cord which helps in the transport of substance to and from the embryo
$R$ : Placenta acts as an endocrine tissue
Which one of the following is not the function of placenta?
By the end of about .......... weeks, the body is covered with fine hair.
Hormones secreted by the placenta to maintain pregnancy are