Which of the following substances can pass through the placenta from the mother into foetus
Proteins
Viruses of small pox
$WBCs$
$RBCs$
Assertion : Senescence is the time when age associated defects are manifested.
Reason : Certain genes may be undergoing sequential switching on and off during one's life.
Read the following paragraph with two blanks : Each testis has about $A$ compartments called as testicular lobules. Each lobule contains $B$ highly coiled seminiferous tubules in which the sperms are produced. The correct option for the two blanks is
$A$ | $B$ |
The fifth cleavage of the fertilized egg of frog results in the formation of
In a simplest type of placenta the foetal blood is separated from the maternal blood by six barriers. How many barriers are lost in human placenta