A cross between F, hybrid and a recessive parent (Ttx tt) gives a ratio of -

Options

A. `1:1`
B. `2:1`
C. `3:1`
D. `4:1 `

Answer

To solve the question regarding the cross between an F1 hybrid (Tt) and a recessive parent (tt), we will follow these steps:

### Step-by-Step Solution:

1. **Identify the Genotypes**:
- The F1 hybrid has the genotype Tt (heterozygous).
- The recessive parent has the genotype tt (homozygous recessive).

2. **Understand the Cross**:
- We are performing a test cross, which involves crossing the F1 hybrid (Tt) with the recessive parent (tt).

3. **Determine the Gametes**:
- The F1 hybrid (Tt) can produce two types of gametes: T (dominant allele) and t (recessive allele).
- The recessive parent (tt) can only produce one type of gamete: t.

4. **Set Up the Punnett Square**:
- Create a Punnett square to visualize the possible offspring from the cross.
- The rows will represent the gametes from the F1 hybrid (T and t), and the columns will represent the gametes from the recessive parent (t).

| | t | t |
|-------|-----|-----|
| **T** | Tt | Tt |
| **t** | tt | tt |

5. **Analyze the Offspring**:
- From the Punnett square, we can see the possible genotypes of the offspring:
- 2 Tt (tall plants)
- 2 tt (dwarf plants)

6. **Calculate the Ratio**:
- The ratio of the offspring is 2 tall (Tt) to 2 dwarf (tt), which simplifies to a 1:1 ratio.

### Final Answer:
The ratio of offspring from the cross between the F1 hybrid (Tt) and the recessive parent (tt) is **1:1**.

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