In a plant gene 'A' is reponsible 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 (aaBa). What is the percentage of dwart white flowered offspring of above cross :-

Options

A. `50%`
B. `6.25%`
C. `12.5%`
D. `50%`

Answer

To solve the problem, we need to analyze the genetic cross between two plants with specified genotypes and determine the percentage of dwarf white-flowered offspring produced from this cross.

### Step-by-Step Solution:

1. **Identify the Genotypes of the Parents:**
- The first parent is a tall red-flowered plant with the genotype **AaBb** (where A = tall, a = dwarf, B = red, b = white).
- The second parent is a dwarf red-flowered plant with the genotype **aaBb** (where aa = dwarf, B = red, b = white).

2. **Determine the Gametes Produced by Each Parent:**
- The first parent (AaBb) can produce the following gametes:
- AB
- Ab
- aB
- ab
- The second parent (aaBb) can produce the following gametes:
- aB
- ab

3. **Set Up a Punnett Square:**
- Create a Punnett square to combine the gametes from both parents. The rows will represent the gametes from the first parent (AaBb) and the columns will represent the gametes from the second parent (aaBb).

| | aB | ab |
|-------|------|------|
| AB | AaBb | Aabb |
| Ab | Aabb | Aabb |
| aB | aaBb | aabb |
| ab | aabb | aabb |

4. **List the Offspring Genotypes:**
- From the Punnett square, we can identify the genotypes of the offspring:
- AaBb (tall, red)
- Aabb (tall, white)
- aaBb (dwarf, red)
- aabb (dwarf, white)

5. **Count the Offspring Genotypes:**
- Total offspring: 8 (from the combinations in the Punnett square)
- Dwarf white-flowered offspring (genotype aabb): 1 (from the combinations)

6. **Calculate the Percentage of Dwarf White Flowered Offspring:**
- The percentage of dwarf white-flowered offspring is calculated as:
\[ \text{Percentage} = \left( \frac{\text{Number of dwarf white offspring}}{\text{Total offspring}} \right) \times 100 \]
\[ \text{Percentage} = \left( \frac{1}{8} \right) \times 100 = 12.5\% \]

### Final Answer:
The percentage of dwarf white-flowered offspring from the cross is **12.5%**.