When a tall pea plant (TT) is crossed with a dwarf plant (tt) what will be the `"F"_(2)` generation?

Options

A. All tall plants
B. All dwarf plants
C. Both tall and dwarf plants in 3 : 1 ratio
D. Both tall and dwarf plants in 1 : 1 ratio

Answer

To solve the question, "When a tall pea plant (TT) is crossed with a dwarf plant (tt), what will be the F2 generation?", we can follow these steps:

### Step 1: Identify the Parent Plants
The parent plants are:
- Tall pea plant (homozygous dominant) = TT
- Dwarf pea plant (homozygous recessive) = tt

### Step 2: Determine the F1 Generation
When we cross the two parent plants (TT x tt), we can determine the gametes produced by each parent:
- The tall plant (TT) can only produce T gametes.
- The dwarf plant (tt) can only produce t gametes.

When these gametes combine, all offspring in the F1 generation will be heterozygous (Tt). Thus, the F1 generation will be:
- F1 Generation: Tt (phenotypically tall, since T is dominant over t)

### Step 3: Self-Cross the F1 Generation
Next, we need to find the F2 generation by self-crossing the F1 plants:
- F1 plants (Tt) will be crossed with each other: Tt x Tt.

### Step 4: Create a Punnett Square
To visualize the genetic combinations, we can use a Punnett square:

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

From the Punnett square, we can see the following combinations:
- 1 TT (homozygous tall)
- 2 Tt (heterozygous tall)
- 1 tt (homozygous dwarf)

### Step 5: Determine the Phenotypic and Genotypic Ratios
Now we can determine the ratios:
- **Phenotypic Ratio**:
- Tall (TT and Tt) = 3 (1 TT + 2 Tt)
- Dwarf (tt) = 1
- Therefore, the phenotypic ratio is 3 tall : 1 dwarf.

- **Genotypic Ratio**:
- Homozygous tall (TT) = 1
- Heterozygous tall (Tt) = 2
- Homozygous dwarf (tt) = 1
- Therefore, the genotypic ratio is 1 TT : 2 Tt : 1 tt.

### Step 6: Conclusion
The F2 generation will consist of:
- 3 tall plants (1 TT and 2 Tt)
- 1 dwarf plant (1 tt)

Thus, the F2 generation will have a phenotypic ratio of 3 tall to 1 dwarf.

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