Colour blindness in man is
Due of deficiency of vitamin $A$
Due of absence of visual purple in retina
Due to absence of rods in retina
A sex linked abnormality
Mendelian disorder may be of
Colour blindness is caused by a single
A normal woman, whose father was colour-blind is married to a normal man. The sons would be
A person may have one gene for normal haemoglobin and one gene for sickle cell haemoglobin. This heterozygous condition is called