Solved Worksheet: Dihybrid Crosses Instructions: For each | Chegg.com - Free Printable

Problem Analysis:

The worksheet involves dihybrid crosses, where two traits (height and color) are being considered simultaneously. The goal is to determine the genotypes of offspring and calculate the phenotypic ratios.

#### Key Information:
1. Traits:
- Height:
- Tall (`T`) is dominant over short (`t`).
- Color:
- Green (`G`) is dominant over white (`g`).

2. Genotypes:
- Tall green pea plant: `TTGg`
- Short white pea plant: `ttgg`

3. Phenotypes:
- Tall/Green: `TTGG`, `TTGg`, `TtGG`, `TtGg`
- Tall/White: `TTgg`, `Ttgg`
- Short/Green: `ttGG`, `ttGg`
- Short/White: `ttgg`

---

Problem 1:

A tall green pea plant (`TTGg`) is crossed with a tall green pea plant (`TTGg`).

#### Step 1: Identify the Genotypes
- Parent 1: `TTGg`
- Parent 2: `TTGg`

#### Step 2: Determine Gametes
For each parent, the possible gametes are determined by separating the alleles for height and color:
- Parent 1 (`TTGg`): Possible gametes are `TG` and `Tg`.
- Parent 2 (`TTGg`): Possible gametes are also `TG` and `Tg`.

#### Step 3: Create the Punnett Square
We will create a 4x4 Punnett square to account for all combinations of the gametes:

| | TG | Tg | TG | Tg |
|-------|-------|-------|-------|-------|
| TG| TTGG | TTGg | TTGG | TTGg |
| Tg| TTGg | TTgg | TTGg | TTgg |
| TG| TTGG | TTGg | TTGG | TTGg |
| Tg| TTGg | TTgg | TTGg | TTgg |

#### Step 4: Analyze the Genotypes and Phenotypes
- Tall/Green: `TTGG`, `TTGg`, `TTGg`, `TTGg`, `TTGg`, `TTGg`, `TTGg`, `TTGg` (8 total)
- Tall/White: `TTgg`, `TTgg` (2 total)
- Short/Green: None (since both parents are `TT`, no `tt` can be produced)
- Short/White: None (since both parents are `TT`, no `tt` can be produced)

#### Step 5: Calculate the Ratios
From the Punnett square:
- Tall/Green: 8
- Tall/White: 2
- Short/Green: 0
- Short/White: 0

The phenotypic ratio is:
$$
\text{Tall/Green : Tall/White : Short/Green : Short/White} = 8 : 2 : 0 : 0
$$

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Final Answer for Problem 1:

$$
\boxed{8 \text{ Tall/Green : } 2 \text{ Tall/White : } 0 \text{ Short/Green : } 0 \text{ Short/White}}
$$

---

Problem 2:

A tall green pea plant (`TTGg`) is crossed with a short white pea plant (`ttgg`).

#### Step 1: Identify the Genotypes
- Parent 1: `TTGg`
- Parent 2: `ttgg`

#### Step 2: Determine Gametes
- Parent 1 (`TTGg`): Possible gametes are `TG` and `Tg`.
- Parent 2 (`ttgg`): Possible gametes are `tg`.

#### Step 3: Create the Punnett Square
We will create a 2x2 Punnett square:

| | TG | Tg |
|-------|-------|-------|
| tg| TtGg | Ttgg |
| tg| TtGg | Ttgg |

#### Step 4: Analyze the Genotypes and Phenotypes
- Tall/Green: `TtGg`, `TtGg` (2 total)
- Tall/White: `Ttgg`, `Ttgg` (2 total)
- Short/Green: None (since one parent is `tt`, no `TT` or `Tt` can produce short plants)
- Short/White: None (since one parent is `tt`, no `TT` or `Tt` can produce short plants)

#### Step 5: Calculate the Ratios
From the Punnett square:
- Tall/Green: 2
- Tall/White: 2
- Short/Green: 0
- Short/White: 0

The phenotypic ratio is:
$$
\text{Tall/Green : Tall/White : Short/Green : Short/White} = 2 : 2 : 0 : 0
$$

---

Final Answer for Problem 2:

$$
\boxed{2 \text{ Tall/Green : } 2 \text{ Tall/White : } 0 \text{ Short/Green : } 0 \text{ Short/White}}
$$

---

Summary of Answers:

1. Problem 1:
$$
\boxed{8 \text{ Tall/Green : } 2 \text{ Tall/White : } 0 \text{ Short/Green : } 0 \text{ Short/White}}
$$

2. Problem 2:
$$
\boxed{2 \text{ Tall/Green : } 2 \text{ Tall/White : } 0 \text{ Short/Green : } 0 \text{ Short/White}}
$$