Chromosome theory of sex determination was propounded by
Bridges
Balbiani
Goldschmidt
None of the above
Sexual reproducation leads to
Both sickle cell anaemia and Huntington’s chorea are
$A$ : Myotonic dystrophy is caused by recessive mutant pleiotropic gene.
$R$ : Gene mutation leads to more synthesis of fibrillin proteins.
$9 : 3 : 3 : 1$ ratio is modified to $9 : 7$ ratio due to
Which of the following phenomena leads to variation in $DNA$?