The recessive genes located on $X$-chromosome in humans are always
Lethal
Sub-lethal
Expressed in males
Expressed in females
Polyploidy can be induced by the application of
Gynaecomastia condition can develop due to
Which pair of chromosomes is concerned with Down's syndrome
Dominant lethal gene is one which
$9 : 3 : 3 : 1$ ratio is modified to $9 : 7$ ratio due to