Question

The monohybrid genotypic ratio is

• A. 1 : 1
• B. 3 : 1
• C. 1 : 2 : 1
• D. 9 : 3 : 3 : 1

Answer 1

Answer: (C)

1 : 2 : 1

Monohybrid cross refers to inheritance of single contrasting trait by two parents at a time. For example, a cross of tall (T) and dwarf (t) pea plants is a monohybrid cross (TT x tt). A monohybrid cross between two pure breeding varieties obtains all dominant $F_1$ generation which in turn produces $F_2$ generation upon selfing and gives the monohybrid phenotypic ratio of 3 (dominant):1 (recessive). The monohybrid genotypic ratio is 1 homozygous tall: 2 heterozygous tall: 1 homozygous dwarf. The monohybrid $F_1$ produces two types of gametes and random fusion of these gametes produces total 4 combinations; 16 combinations are produced in a dihybrid ratio. Thus, the correct answer is option C.