Which is mismatched

Options

A. `Tt xx Tt-3:1`
B. `Tt xx t t -2:1`
C. `Tt Yy xx t t y y-1:1:1:1:1`
D. `TtYy xx Tt Yy-9:3:3:1`

Answer

To determine which option is mismatched, we will analyze each provided genetic cross step by step.

### Step 1: Analyze the first option
- **Cross:** Small t (tt) x Capital T (TT)
- **Expected Ratio:**
- The offspring will be 50% Tt (tall) and 50% tt (dwarf).
- This results in a ratio of 1 tall : 1 dwarf.
- **Conclusion:** This option is correctly matched.

### Step 2: Analyze the second option
- **Cross:** Capital T (Tt) x Small t (tt)
- **Expected Ratio:**
- The offspring will be 50% Tt (tall) and 50% tt (dwarf).
- This results in a ratio of 1 tall : 1 dwarf.
- **Conclusion:** The expected ratio is 1:1, not 2:1 as stated. Therefore, this option is mismatched.

### Step 3: Analyze the third option
- **Cross:** Dihybrid cross (e.g., AaBb x AaBb)
- **Expected Ratio:**
- The expected phenotypic ratio for a dihybrid cross is 9:3:3:1.
- **Conclusion:** This option is correctly matched.

### Step 4: Analyze the fourth option
- **Cross:** Test cross with a homozygous recessive (e.g., Aa x aa)
- **Expected Ratio:**
- The expected ratio for a test cross is 1:1 for dominant to recessive traits.
- **Conclusion:** This option is correctly matched.

### Final Conclusion
After analyzing all the options, the mismatched option is the second one, where the expected ratio is incorrectly stated as 2:1 instead of the correct 1:1.

### Summary of the Answer:
The mismatched option is the second one, which states a ratio of 2:1 instead of the correct 1:1.

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