When a heterozygous tall pea plant was selfed total 128 seeds were obtained in `F_(2)` generation. Find out the number of seeds with genotype tt ?

Options

A. 128
B. 64
C. 32
D. 96

Answer

To solve the problem of finding the number of seeds with the genotype tt from a selfed heterozygous tall pea plant (Tt), we can follow these steps:

### Step-by-Step Solution:

1. **Identify the Genotypes of the Parents**:
The heterozygous tall pea plant has the genotype Tt (where T = tall and t = short). Since it is selfed, it will be crossed with another Tt plant.

2. **Determine the Gametes**:
Each parent can produce two types of gametes: T and t. Therefore, the gametes from both parents are:
- Parent 1: T, t
- Parent 2: T, t

3. **Set Up a Punnett Square**:
Create a Punnett square to visualize the possible offspring genotypes. The Punnett square will look like this:

```
T t
----------------
T | TT | Tt |
----------------
t | Tt | tt |
----------------
```

4. **Analyze the Offspring Genotypes**:
From the Punnett square, we can see the possible genotypes of the offspring:
- TT (homozygous tall)
- Tt (heterozygous tall)
- Tt (heterozygous tall)
- tt (homozygous short)

The ratio of genotypes is:
- TT: 1
- Tt: 2
- tt: 1

5. **Calculate the Ratio of tt**:
The ratio of tt (short) to the total offspring is 1 out of 4. Therefore, the fraction of tt is 1/4.

6. **Calculate the Total Number of Seeds**:
Given that a total of 128 seeds were obtained, we can calculate the number of seeds with the genotype tt:
\[ \text{Number of seeds with genotype tt} = \frac{1}{4} \times 128 = 32 \]

7. **Conclusion**:
The number of seeds with the genotype tt is 32.

### Final Answer:
The number of seeds with genotype tt is **32**.