Percentage of pure breeding `F_(2)` individual of a monohybrid cross would be

Options

A. 0.75
B. 0.5
C. 0.25
D. 0.125

Answer

To determine the percentage of pure breeding F2 individuals in a monohybrid cross, we can follow these steps:

### Step 1: Understand the Monohybrid Cross
A monohybrid cross involves two individuals that differ in a single trait. For example, if we consider a trait controlled by a single gene with two alleles (dominant and recessive), we can denote the dominant allele as "T" and the recessive allele as "t".

### Step 2: Determine the Genotypes of the F1 Generation
When two pure breeding parents (TT and tt) are crossed, all the offspring in the F1 generation will be heterozygous (Tt). This is because each parent contributes one allele, resulting in Tt.

### Step 3: Perform the F2 Generation Cross
When the F1 individuals (Tt) are crossed with each other (Tt x Tt), we can use a Punnett square to determine the genotypes of the F2 generation. The possible combinations are:
- TT (homozygous dominant)
- Tt (heterozygous)
- Tt (heterozygous)
- tt (homozygous recessive)

### Step 4: Count the Genotypes
From the Punnett square, we find:
- 1 TT (homozygous dominant)
- 2 Tt (heterozygous)
- 1 tt (homozygous recessive)

This gives us a total of 4 offspring in the F2 generation.

### Step 5: Identify Pure Breeding Individuals
Pure breeding individuals are those that are homozygous, which includes both TT and tt. In our case, there are:
- 1 TT (homozygous dominant)
- 1 tt (homozygous recessive)

This means there are 2 pure breeding individuals out of a total of 4.

### Step 6: Calculate the Percentage
To find the percentage of pure breeding individuals, we use the formula:
\[ \text{Percentage of pure breeding individuals} = \left( \frac{\text{Number of pure breeding individuals}}{\text{Total number of individuals}} \right) \times 100 \]
Substituting the values:
\[ \text{Percentage} = \left( \frac{2}{4} \right) \times 100 = 50\% \]

### Conclusion
Thus, the percentage of pure breeding F2 individuals in a monohybrid cross is **50%** or **0.5**.

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