Heterozygous round and yellow seeded pea plants were selfed and total 800 seeds are collected. What is the total number of seeds with first dominant and second recessive traits ?

Options

A. 950
B. 300
C. 200
D. 150

Answer

To solve the problem, we need to determine the number of seeds that exhibit the dominant trait for seed shape (round) and the recessive trait for seed color (green) from a self-cross of heterozygous round and yellow seeded pea plants.

### Step-by-Step Solution:

1. **Identify the Genotypes**:
- Round seeds are represented by the dominant allele (R), and green seeds are represented by the recessive allele (r).
- Yellow seeds are represented by the dominant allele (Y), and green seeds are represented by the recessive allele (y).
- The heterozygous round and yellow seeded plants have the genotype RrYy.

2. **Determine Gametes**:
- When selfing RrYy plants, the possible gametes produced are: RY, Ry, rY, and ry.

3. **Set Up the Punnett Square**:
- Create a 4x4 Punnett square to determine the genotypes of the offspring from the cross RrYy x RrYy.

4. **Fill in the Punnett Square**:
- The combinations of gametes will give us the following genotypes:
- RRYY
- RRYy
- RrYY
- RrYy
- Rryy
- rrYY
- rrYy
- rryy
- The phenotypic ratio from this cross will be 9:3:3:1.

5. **Identify the Desired Phenotype**:
- We are looking for seeds that are round (dominant trait) and green (recessive trait).
- This corresponds to the genotype Rryy.

6. **Calculate the Ratio**:
- From the phenotypic ratio, we know:
- 9 Round Yellow (R_Y_)
- 3 Round Green (R_yy)
- 3 Wrinkled Yellow (rrY_)
- 1 Wrinkled Green (rryy)
- The round and green seeds (Rryy) represent 3 out of a total of 16 phenotypes.

7. **Calculate the Total Number of Round Green Seeds**:
- If there are 800 seeds in total, we can calculate the number of round green seeds:
\[ \text{Number of Round Green Seeds} = \left(\frac{3}{16}\right) \times 800 = 150 \]

### Final Answer:
The total number of seeds with the first dominant trait (round) and the second recessive trait (green) is **150**.