Question

In a plant, gene 'A' is responsible for tallness and its recessive allele 'a' for dwarfness and 'B' is responsible for red flower colour, and it's recessive allele 'b' for white flower colour. A tall and red-flowered plant with genotype AaBb crossed with dwarf and red-flowered (aaBb). What is the percentage of dwarf white-flowered offspring of the above cross?

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

Answer 1

The correct option is C 12.5%

Parent: AaBb × aaBb
Cross:
$\begin{array}{ccccc}& \text{AB}& \text{Ab}& \text{aB}& \text{ab}\\ \text{aB}& \text{AaBB (tall and red)}& \text{AaBb (tall and red)}& \text{aaBB (dwarf and red)}& \text{aaBb (dwarf and red)}\\ \text{ab}& \text{AaBb (tall and red)}& \text{Aabb (tall and white)}& \text{aaBb (dwarf and red)}& \text{aabb (dwarf and white)}\end{array}$

Out of 8 offsprings, 1 offspring has dwarf white-flowered. Hence, the required precentage$=\frac{1}{8}\times 100\%=12.5\%$