The defect sickle-cell anaemia is caused by the ______ of glutamic acid by valine at the $6^{th}$ position of the ______ globin chain of the haemoglobin molecule.
Substitution, $\beta$
Deletion, $\alpha$
Duplication, $\beta$
Translocation, $\alpha$
Sometimes the separation of twins is incomplete and these are borne attached are remain so even after. Such twins are known as
Experimental verification of the chromosomal theory of inheritance was given by
Sex linked traits are the traits determined by
The traits controlled by the genes located on $X$ chromosome of human beings are said to be
Haemophilia is also called