Question

In a plant, gene ‘A’ is responsible for tallness and its recessive allele ‘a’ for dwarfness and gene ‘B’ is responsible for red coloured flower while its recessive allele ‘b’ for white coloured flower. A tall and red-flowered plant with genotype AaBb is crossed with dwarf and red flower with genotype aaBb. What percentage of their offspring would be dwarf white-flowered?

• A. 50%
• B. 25%
• C. 6.25%
• D. 12.5%

Answer 1

The correct option is D 12.5%

Parents: (AaBb) × (aaBb)

Gametes: For AaBb- AB, Ab, aB, ab
For aaBb- aB, ab, aB, ab

Punnett square:

Phenotype:
Tall and Red flower plants- 6
Tall and white flower plants-2
Dwarf and Red flower plants-6
Dwarf and White flower plants-2

(Dwarf andWhite flowered offspring/Total number of offspring) × 100
= (2/16) × 100
= 12.5%