Frequency of Down’s syndrome increases when the maternal age is

Jumping genes in maize were discovered by

When a diploid female plant is crossed with a tetraploid male, the ploidy of endosperm cells in the resulting seed is

A hereditary disease which is never passed on from father to son is

In man, four phenotypes of blood groups are due to the presence of antigen-$A$ and antigen-$B$ on the $RBC.$ The chromosome that has the gene to control these antigens is

Animal which remains male initially, then changes to female $(Tapeworm\, proglottides)$ is called