Question
In a 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 in the gene for seed color follow the law of independent adornment and are non sex-linked. in a cross between two RrYy parents predict the fraction of offspring with round yellow seeds.
A. 1/2
B.3/4
C. 9/16
D. 15/16
A. 1/2
B.3/4
C. 9/16
D. 15/16
Answers
GPT-4o mini
To determine the fraction of offspring with round yellow seeds from a cross between two RrYy parents, we can use a Punnett square.
1. **Identify the Alleles**:
- Seed Shape: Round (R) is dominant to Wrinkled (r)
- Seed Color: Yellow (Y) is dominant to Green (y)
Thus, the alleles for the two parents are RrYy.
2. **Gamete Formation**:
Each parent can produce four types of gametes due to independent assortment:
- RY
- Ry
- rY
- ry
3. **Punnett Square**:
We create a 4x4 Punnett square to determine the genotypes of the offspring.
\[
\begin{array}{c|c|c|c|c}
& RY & Ry & rY & ry \\
\hline
RY & RRYY & RRYy & RrYY & RrYy \\
\hline
Ry & RRYy & RRyy & RrYy & Rryy \\
\hline
rY & RrYY & RrYy & rrYY & rrYy \\
\hline
ry & RrYy & Rryy & rrYy & rryy \\
\end{array}
\]
4. **Count the Desired Phenotypes**:
We are looking for offspring with round yellow seeds. Round seeds can be either RY (homozygous dominant) or Rr (heterozygous), and yellow seeds can be either YY or Yy. Thus, we need to count the offspring that have at least one R (R or r) and at least one Y (Y or y):
The combinations for round yellow seeds are:
- RRYY
- RRYy
- RrYY
- RrYy
- RRYy (already counted)
- RrYy (already counted)
- RrYY (already counted)
Totaling the count gives:
- RRYY: 1
- RRYy: 2
- RrYY: 2
- RrYy: 4
Thus, the total number of round yellow offspring is:
\(1 + 2 + 2 + 4 = 9\)
5. **Total Offspring**:
Since there are a total of 16 possibilities in the Punnett square (because \(4 x 4 = 16\)), the fraction of round yellow seeds will be:
\[
\text{Fraction} = \frac{9}{16}
\]
Thus, the fraction of offspring with round yellow seeds is \( \frac{9}{16} \).
**Final Answer: C. 9/16**
1. **Identify the Alleles**:
- Seed Shape: Round (R) is dominant to Wrinkled (r)
- Seed Color: Yellow (Y) is dominant to Green (y)
Thus, the alleles for the two parents are RrYy.
2. **Gamete Formation**:
Each parent can produce four types of gametes due to independent assortment:
- RY
- Ry
- rY
- ry
3. **Punnett Square**:
We create a 4x4 Punnett square to determine the genotypes of the offspring.
\[
\begin{array}{c|c|c|c|c}
& RY & Ry & rY & ry \\
\hline
RY & RRYY & RRYy & RrYY & RrYy \\
\hline
Ry & RRYy & RRyy & RrYy & Rryy \\
\hline
rY & RrYY & RrYy & rrYY & rrYy \\
\hline
ry & RrYy & Rryy & rrYy & rryy \\
\end{array}
\]
4. **Count the Desired Phenotypes**:
We are looking for offspring with round yellow seeds. Round seeds can be either RY (homozygous dominant) or Rr (heterozygous), and yellow seeds can be either YY or Yy. Thus, we need to count the offspring that have at least one R (R or r) and at least one Y (Y or y):
The combinations for round yellow seeds are:
- RRYY
- RRYy
- RrYY
- RrYy
- RRYy (already counted)
- RrYy (already counted)
- RrYY (already counted)
Totaling the count gives:
- RRYY: 1
- RRYy: 2
- RrYY: 2
- RrYy: 4
Thus, the total number of round yellow offspring is:
\(1 + 2 + 2 + 4 = 9\)
5. **Total Offspring**:
Since there are a total of 16 possibilities in the Punnett square (because \(4 x 4 = 16\)), the fraction of round yellow seeds will be:
\[
\text{Fraction} = \frac{9}{16}
\]
Thus, the fraction of offspring with round yellow seeds is \( \frac{9}{16} \).
**Final Answer: C. 9/16**