$A$ doctor's son:

$A$ male human is heterozygous for autosomal genes $A$ and $B$ and is also hemizygous for the hemophilic gene $h$. What proportion of his sperms will be $abh$?

Which of the following statements is correct?

Interspecific crosses are rare in nature and intergeneric crosses are almost unknown. Why?

Read all the given statements carefully and determine the number of correct statements.
$(1)$ Mutations are not hereditary.
$(2)$ Male $Drosophila$ flies do not show crossing over.
$(3)$ In honeybees,the male bee is diploid.
$(4)$ In a frame-shift mutation,one nitrogen base is replaced by another nitrogen base at a specific position.
$(5)$ Genes are responsible for inheritance.

Select the incorrect statement from the following.