A cross between yellow flowered and round fruit ( both dominant ) bearing plant and white flowered elongated fruit ( both recessive ) bearing plant yielded 20 plants in `F_(1)` progeny which formed 960 plants in `F_(2)` generation. The number of plants with yellow flowered and round fruits in `F_(1)` and `F_(2)` generations would be

Options

A. 20960
B. 20540
C. 10180
D. 10,60

Answer

To solve the problem, we need to analyze the genetic cross between the two plants and determine the number of plants with yellow flowers and round fruits in both the F1 and F2 generations.

### Step-by-Step Solution:

1. **Identify the Genotypes of the Parent Plants:**
- The plant with yellow flowers and round fruits is homozygous dominant for both traits: YYRR.
- The plant with white flowers and elongated fruits is homozygous recessive for both traits: yyrr.

2. **Determine the Genotype of the F1 Generation:**
- When these two plants are crossed (YYRR x yyrr), all F1 progeny will inherit one allele from each parent. Thus, the genotype of the F1 generation will be:
- YyRr (heterozygous for both traits).
- Since yellow flowers (Y) and round fruits (R) are dominant traits, all F1 plants will exhibit these dominant phenotypes.

3. **Count the Number of F1 Plants:**
- According to the problem, the F1 generation yielded 20 plants, all of which have yellow flowers and round fruits.

4. **Self-Cross the F1 Generation to Produce F2 Generation:**
- The F1 plants (YyRr) will be self-pollinated. The gametes produced will be:
- YR, Yr, yR, yr.
- The resulting F2 generation can be determined using a Punnett square or by applying the dihybrid ratio.

5. **Determine the Phenotypic Ratio in F2 Generation:**
- The phenotypic ratio for a dihybrid cross (YyRr x YyRr) is 9:3:3:1.
- This means:
- 9 will have yellow flowers and round fruits (dominant traits),
- 3 will have yellow flowers and elongated fruits,
- 3 will have white flowers and round fruits,
- 1 will have white flowers and elongated fruits.

6. **Calculate the Total Number of F2 Plants:**
- The problem states that there are 960 plants in the F2 generation.

7. **Calculate the Number of Plants with Yellow Flowers and Round Fruits in F2:**
- Using the phenotypic ratio:
- (9/16) of the total plants will have yellow flowers and round fruits.
- Therefore, the number of plants with yellow flowers and round fruits in F2 = (9/16) * 960 = 540.

### Final Answer:
- The number of plants with yellow flowers and round fruits in the F1 generation is **20**.
- The number of plants with yellow flowers and round fruits in the F2 generation is **540**.