Genetics practice worksheet using SpongeBob SquarePants characters to teach Punnett squares and inheritance patterns.

Problem Analysis and Solution

The worksheet involves genetics problems using Punnett squares to determine the probabilities of different genotypes and phenotypes for offspring. Let's solve each problem step by step.

---

Problem 6: Squidward and His Bride

#### Given Information:
- Squidward has light blue skin, which is the dominant trait (`B`).
- His bride has light green skin, which is the recessive trait (`b`).
- Squidward is "purebred," meaning he is homozygous dominant (`BB`).
- His bride is homozygous recessive (`bb`).

#### Task:
1. Create a Punnett square.
2. List possible genotypes and phenotypes for their children.
3. Calculate the chances of a child with light blue skin.
4. Calculate the chances of a child with light green skin.
5. Determine if Squidward's children would still be considered "purebred."

#### Solution:

##### Step 1: Create the Punnett Square
Squidward's genotype: `BB`
Bride's genotype: `bb`

| | b | b |
|-----|-----|-----|
| B | Bb | Bb |
| B | Bb | Bb |

##### Step 2: List Possible Genotypes and Phenotypes
- Genotypes: All offspring will have the genotype `Bb`.
- Phenotypes: Since `B` (light blue) is dominant over `b` (light green), all offspring will have light blue skin.

##### Step 3: Calculate Chances
- Light Blue Skin: 100% (all offspring are `Bb`, which expresses the dominant phenotype).
- Light Green Skin: 0% (no offspring are `bb`).

##### Step 4: Are the Children Purebred?
- No, the children are not purebred. They are heterozygous (`Bb`), meaning they carry one dominant allele (`B`) and one recessive allele (`b`).

#### Final Answers for Problem 6:
A. Genotypes: `Bb`, Phenotypes: Light blue skin
B. Chances of light blue skin: 100%
C. Chances of light green skin: 0%
D. No, the children would not be considered purebred because they are heterozygous (`Bb`).

---

Problem 7: Squidward's Son and His Wife

#### Given Information:
- Squidward's son is heterozygous for light blue skin (`Bb`).
- His wife is also heterozygous for light blue skin (`Bb`).

#### Task:
1. Create a Punnett square.
2. List possible genotypes and phenotypes for their children.
3. Calculate the chances of a child with light blue skin.
4. Calculate the chances of a child with light green skin.

#### Solution:

##### Step 1: Create the Punnett Square
Son's genotype: `Bb`
Wife's genotype: `Bb`

| | B | b |
|-----|-----|-----|
| B | BB | Bb |
| b | Bb | bb |

##### Step 2: List Possible Genotypes and Phenotypes
- Genotypes: `BB`, `Bb`, `Bb`, `bb`
- Phenotypes:
- `BB` and `Bb`: Light blue skin (dominant phenotype)
- `bb`: Light green skin (recessive phenotype)

##### Step 3: Calculate Chances
- Light Blue Skin:
- Genotypes: `BB` and `Bb` (3 out of 4 squares)
- Probability: \( \frac{3}{4} = 75\% \)
- Light Green Skin:
- Genotype: `bb` (1 out of 4 squares)
- Probability: \( \frac{1}{4} = 25\% \)

#### Final Answers for Problem 7:
A. Genotypes: `BB`, `Bb`, `Bb`, `bb`; Phenotypes: Light blue skin (BB, Bb), Light green skin (bb)
B. Chances of light blue skin: 75%
C. Chances of light green skin: 25%

---

Problem 8: Mr. Krabs and His Wife

#### Given Information:
- Mr. Krabs is homozygous dominant for tall eyeballs (`TT`).
- Mrs. Krabs is heterozygous for tall eyeballs (`Tt`).
- Tall eyeballs (`T`) are dominant over short eyeballs (`t`).

#### Task:
1. Create a Punnett square.
2. List possible genotypes and phenotypes for their children.
3. Determine if the hospital made a mistake by mixing up the baby.

#### Solution:

##### Step 1: Create the Punnett Square
Mr. Krabs' genotype: `TT`
Mrs. Krabs' genotype: `Tt`

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

##### Step 2: List Possible Genotypes and Phenotypes
- Genotypes: `TT`, `Tt`, `TT`, `Tt`
- Phenotypes:
- `TT` and `Tt`: Tall eyeballs (dominant phenotype)
- No `tt` (short eyeballs) because neither parent carries two recessive alleles.

##### Step 3: Did the Hospital Make a Mistake?
- All possible offspring of Mr. Krabs and Mrs. Krabs will have at least one dominant allele (`T`), resulting in tall eyeballs.
- Since the baby has short eyeballs (`tt`), it is impossible for this baby to be theirs genetically.
- Therefore, the hospital likely made a mistake by mixing up the baby.

#### Final Answers for Problem 8:
A. Genotypes: `TT`, `Tt`, `TT`, `Tt`; Phenotypes: Tall eyeballs (TT, Tt)
B. Yes, the hospital made a mistake because it is genetically impossible for Mr. Krabs and Mrs. Krabs to have a baby with short eyeballs.

---

Final Answer Summary:

1. Problem 6:
- A. Genotypes: `Bb`, Phenotypes: Light blue skin
- B. 100%
- C. 0%
- D. No, the children are heterozygous (`Bb`).

2. Problem 7:
- A. Genotypes: `BB`, `Bb`, `Bb`, `bb`; Phenotypes: Light blue skin (BB, Bb), Light green skin (bb)
- B. 75%
- C. 25%

3. Problem 8:
- A. Genotypes: `TT`, `Tt`, `TT`, `Tt`; Phenotypes: Tall eyeballs (TT, Tt)
- B. Yes, the hospital made a mistake.

Final Boxed Answers:
\[
\boxed{
\begin{array}{l}
\text{Problem 6: B. 100%, C. 0%, D. No} \\
\text{Problem 7: B. 75%, C. 25%} \\
\text{Problem 8: B. Yes}
\end{array}
}
\]