Dwarf pea was treated with gibberellic acid. It became as tall pea plants. If these pea plants are crossed with pure tall plants. What will be the phenotype ratio in `F_(2)` generation?

Options

A. All dwarf plants
B. 50 % tall and 50% dwarf plants
C. 75% tall and 25% dwarf plants
D. 100% tall plants

Answer

To solve the question regarding the dwarf pea plants treated with gibberellic acid and their crossing with pure tall plants, we can follow these steps:

### Step 1: Understand the Genetic Makeup
- The dwarf pea plant is represented by the genotype "tt" (homozygous recessive), while the pure tall plant is represented by "TT" (homozygous dominant).

### Step 2: Cross the Dwarf and Tall Plants
- When we cross the dwarf pea plants (tt) with pure tall plants (TT), the resulting offspring (F1 generation) will all be heterozygous tall (Tt). This is because the tall allele (T) is dominant over the dwarf allele (t).

### Step 3: Analyze the F1 Generation
- The F1 generation consists entirely of Tt plants, which will all exhibit the tall phenotype due to the presence of the dominant T allele.

### Step 4: Self-Cross the F1 Generation
- Now, if we self-cross the F1 generation (Tt x Tt), we can use a Punnett square to determine the genotypic and phenotypic ratios of the F2 generation.

### Step 5: Create a Punnett Square
- The Punnett square for Tt x Tt will yield the following combinations:
- TT (homozygous tall)
- Tt (heterozygous tall)
- Tt (heterozygous tall)
- tt (homozygous dwarf)

### Step 6: Determine the Phenotypic Ratio
- From the Punnett square, we can see that:
- 3 out of 4 offspring will be tall (TT or Tt)
- 1 out of 4 offspring will be dwarf (tt)
- Therefore, the phenotypic ratio in the F2 generation will be 3 tall: 1 dwarf.

### Conclusion
- The final phenotype ratio in the F2 generation is 3 tall plants to 1 dwarf plant.