The first definite proof of mutagenic action of $X$-rays was given by

A recessive gene is one which

Which one of the following is a dominant trait

If in a child of $10$ years ages of the intelligence is of $14$ years child, the $I.Q.$ of this child would be

Improvement of human race through hereditary qualities is called

When closely placed genes on the same chromosome are inherited together the phenomenon is known as