What is the genotypic and phenotypic ratio of monohybrid test cross :-

Options

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

Answer

To determine the genotypic and phenotypic ratios of a monohybrid test cross, we can follow these steps:

### Step 1: Understand the Basics of Monohybrid Crosses
A monohybrid cross involves a single trait with two alleles. In this case, we will use:
- Dominant allele: T (tall)
- Recessive allele: t (short)

### Step 2: Determine the F1 Generation
When we perform a monohybrid cross between two homozygous parents (TT x tt), the F1 generation will all be heterozygous (Tt).

### Step 3: Set Up the Test Cross
A test cross is performed by crossing the F1 individual (Tt) with a homozygous recessive individual (tt). The cross can be represented as:
- Tt (F1) x tt (test cross)

### Step 4: Determine Gametes
From the F1 individual (Tt), the possible gametes are:
- T (dominant)
- t (recessive)

From the homozygous recessive individual (tt), the only possible gamete is:
- t (recessive)

### Step 5: Create a Punnett Square
We can set up a Punnett square to visualize the offspring from the test cross:

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

### Step 6: Analyze the Offspring
From the Punnett square, we can see the possible genotypes of the offspring:
- Tt (tall) - 2 offspring
- tt (short) - 2 offspring

### Step 7: Calculate Genotypic Ratio
The genotypic ratio is:
- 2 Tt : 2 tt, which simplifies to 1 : 1

### Step 8: Calculate Phenotypic Ratio
The phenotypic ratio is:
- 2 tall (Tt) : 2 short (tt), which also simplifies to 1 : 1

### Final Answer
Thus, the genotypic ratio of the monohybrid test cross is 1:1, and the phenotypic ratio is also 1:1.

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