What is the probability of production of homozygous tall offsprings in a cross between two heterozygous tall pea plants ?

Options

A. Zero
B. `50%`
C. `75%`
D. `100%`

Answer

To determine the probability of producing homozygous tall offspring from a cross between two heterozygous tall pea plants (Tt x Tt), we can follow these steps:

### Step 1: Define the Genotypes
- **T** = dominant allele for tallness
- **t** = recessive allele for dwarfism
- The heterozygous tall pea plants can be represented as Tt.

### Step 2: Set Up the Punnett Square
To find the offspring's genotypes, we can set up a Punnett square for the cross Tt x Tt:

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

### Step 3: Determine the Offspring Genotypes
From the Punnett square, we can see the possible genotypes of the offspring:
- **TT** (homozygous tall)
- **Tt** (heterozygous tall)
- **tt** (homozygous dwarf)

### Step 4: Count the Genotypes
- **TT**: 1
- **Tt**: 2
- **tt**: 1

### Step 5: Calculate the Probability of Homozygous Tall Offspring
The total number of offspring genotypes is 4 (1 TT + 2 Tt + 1 tt). The probability of getting homozygous tall offspring (TT) is:

\[ \text{Probability of TT} = \frac{\text{Number of TT}}{\text{Total Offspring}} = \frac{1}{4} \]

### Step 6: Convert to Percentage
To express this probability as a percentage:

\[ \text{Percentage} = \left( \frac{1}{4} \right) \times 100 = 25\% \]

### Conclusion
The probability of producing homozygous tall offspring (TT) from a cross between two heterozygous tall pea plants (Tt x Tt) is **25%**.

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