What proportion of individuals will have the genotype PpQQRrSstt if their parents had genotypes PPQqRRssTt and PpQQrrSSTt ?

Options

A. `1//8`
B. `1//16`
C. `1//256`
D. `1//64`

Answer

To determine the proportion of individuals with the genotype PpQQRrSstt from the parental genotypes PPQqRRssTt and PpQQrrSSTt, we will analyze each gene separately and then multiply the probabilities together.

### Step-by-Step Solution:

1. **Analyze the P gene:**
- Parent 1: PP
- Parent 2: Pp
- Possible gametes from Parent 1: P
- Possible gametes from Parent 2: P, p
- Punnett square results:
- PP (from P and P)
- Pp (from P and p)
- Progeny genotypes: PP, Pp
- Proportion of Pp: 1 out of 2 (Pp and PP) = 1/2

2. **Analyze the Q gene:**
- Parent 1: QQ
- Parent 2: QQ
- Possible gametes from both parents: Q
- Punnett square results:
- QQ (from Q and Q)
- Progeny genotype: QQ
- Proportion of QQ: 2 out of 2 (only QQ) = 1

3. **Analyze the R gene:**
- Parent 1: RR
- Parent 2: rr
- Possible gametes from Parent 1: R
- Possible gametes from Parent 2: r
- Punnett square results:
- Rr (from R and r)
- Progeny genotype: Rr
- Proportion of Rr: 4 out of 4 (only Rr) = 1

4. **Analyze the S gene:**
- Parent 1: ss
- Parent 2: SS
- Possible gametes from Parent 1: s
- Possible gametes from Parent 2: S
- Punnett square results:
- Ss (from S and s)
- Progeny genotype: Ss
- Proportion of Ss: 4 out of 4 (only Ss) = 1

5. **Analyze the T gene:**
- Parent 1: Tt
- Parent 2: Tt
- Possible gametes from both parents: T, t
- Punnett square results:
- TT, Tt, Tt, tt
- Progeny genotypes: TT, Tt, tt
- Proportion of tt: 1 out of 4 (only tt) = 1/4

6. **Calculate the overall proportion:**
- Combine the proportions:
\[ \text{Total Proportion} = \left(\frac{1}{2}\right) \times 1 \times 1 \times 1 \times \left(\frac{1}{4}\right) = \frac{1}{2} \times \frac{1}{4} = \frac{1}{8} \]

### Final Answer:
The proportion of individuals with the genotype PpQQRrSstt is **1/8**.