Down’s syndrome is associated with

A. Trisomy of 21st chromosome

B. Mental retardation

C. Furrowed tongue

D. Congenital heart disease

Choose correct option:

The following family tree traces the occurrence of a rare genetic disease. The filled symbols signify the individuals with the disease, whereas the open symbols signify healthy individuals.

Based on this information, the disease is most likely to be:

The law based on the fact that the alleles do not show blending also proposes that:

(a) A gamete receives only one of the two factors.

(b) Both the characters are recovered as such in ${\mathrm{F}}_2$-generation.