Question
In pea plants, round seeds (R) are dominant to wrinkled seeds (r), and yellow seed color (Y) is dominant to green seed color (y) . The gene for seed shape and the gene for seed color follow the law of independent assortment and are not sex-linked. In a cross between two RrYy parents, predict the fraction of offspring with round, yellow seeds. Responses A 1/21/2 B 3/43/4 C 9/169/16 D 15/16
Answers
GPT-4o mini
To solve this problem, we first need to analyze the genetics of the pea plant traits for seed shape and seed color.
1. **Traits and Alleles**:
- Seed shape: Round (R) is dominant to wrinkled (r)
- Seed color: Yellow (Y) is dominant to green (y)
2. **Parental Genotype**:
- The parents are both RrYy, which means they are heterozygous for both traits.
3. **Gamete Formation**:
- Each parent can produce four types of gametes based on the combinations of alleles:
- RY (Round, Yellow)
- Ry (Round, Green)
- rY (Wrinkled, Yellow)
- ry (Wrinkled, Green)
4. **Punnett Square Setup**:
- We can use a Punnett square to determine the offspring from the two RrYy parents. The combinations will fill a 4x4 grid since each parent can produce 4 types of gametes.
5. **Punnett Square Results**:
- The resulting genotypes and phenotypes are:
- RY x RY → Round, Yellow
- RY x Ry → Round, Yellow
- RY x rY → Round, Yellow
- RY x ry → Round, Green
- Ry x RY → Round, Yellow
- Ry x Ry → Round, Green
- Ry x rY → Wrinkled, Yellow
- Ry x ry → Wrinkled, Green
- rY x RY → Round, Yellow
- rY x Ry → Wrinkled, Yellow
- rY x rY → Wrinkled, Yellow
- rY x ry → Wrinkled, Green
- ry x RY → Round, Green
- ry x Ry → Wrinkled, Green
- ry x rY → Wrinkled, Yellow
- ry x ry → Wrinkled, Green
6. **Count the Phenotypes**:
Based on the combinations filled in, we get:
- Round, Yellow: 9 (RY and Ry combinations)
- Round, Green: 3 (Ry and ry combinations)
- Wrinkled, Yellow: 3 (rY and Ry combinations)
- Wrinkled, Green: 1 (ry and ry combination)
7. **Fraction of Round, Yellow Seeds**:
- There are a total of 16 combinations (4 from each parent giving 4x4 = 16).
- The number of Round, Yellow offspring = 9.
Thus, the fraction of offspring with round, yellow seeds will be \( \frac{9}{16} \).
The correct answer is **C 9/16**.
1. **Traits and Alleles**:
- Seed shape: Round (R) is dominant to wrinkled (r)
- Seed color: Yellow (Y) is dominant to green (y)
2. **Parental Genotype**:
- The parents are both RrYy, which means they are heterozygous for both traits.
3. **Gamete Formation**:
- Each parent can produce four types of gametes based on the combinations of alleles:
- RY (Round, Yellow)
- Ry (Round, Green)
- rY (Wrinkled, Yellow)
- ry (Wrinkled, Green)
4. **Punnett Square Setup**:
- We can use a Punnett square to determine the offspring from the two RrYy parents. The combinations will fill a 4x4 grid since each parent can produce 4 types of gametes.
5. **Punnett Square Results**:
- The resulting genotypes and phenotypes are:
- RY x RY → Round, Yellow
- RY x Ry → Round, Yellow
- RY x rY → Round, Yellow
- RY x ry → Round, Green
- Ry x RY → Round, Yellow
- Ry x Ry → Round, Green
- Ry x rY → Wrinkled, Yellow
- Ry x ry → Wrinkled, Green
- rY x RY → Round, Yellow
- rY x Ry → Wrinkled, Yellow
- rY x rY → Wrinkled, Yellow
- rY x ry → Wrinkled, Green
- ry x RY → Round, Green
- ry x Ry → Wrinkled, Green
- ry x rY → Wrinkled, Yellow
- ry x ry → Wrinkled, Green
6. **Count the Phenotypes**:
Based on the combinations filled in, we get:
- Round, Yellow: 9 (RY and Ry combinations)
- Round, Green: 3 (Ry and ry combinations)
- Wrinkled, Yellow: 3 (rY and Ry combinations)
- Wrinkled, Green: 1 (ry and ry combination)
7. **Fraction of Round, Yellow Seeds**:
- There are a total of 16 combinations (4 from each parent giving 4x4 = 16).
- The number of Round, Yellow offspring = 9.
Thus, the fraction of offspring with round, yellow seeds will be \( \frac{9}{16} \).
The correct answer is **C 9/16**.