In a cross between white-flowered parents, $F_1$ progeny was uniformly purple-flowered. The $F_2$ progeny showed a phenotypic ratio $9 : 7$ between purple-flowered and white-flowered plants. The above result indicates that the flower colour is controlled by
Two alleles
One allele
Three alleles
Four alleles
Coupling and repulsion are the two faces of
Experimental verification of the chromosomal theory of inheritance was given by
Mental retardation in man, associated with sex chromosomal abnormality is usually due to
The "cri-du-chat" syndrome is caused by change in chromosome structure involving
Which of the following is an inherited trait in man