Bikini Bottom Genetics | PDF | Genotype | Dominance (Genetics) - Free Printable

You’ve uploaded a genetics worksheet titled “Bikini Bottom Genetics” featuring SpongeBob and Patrick. The worksheet uses cartoon characters to teach basic Mendelian genetics — dominant vs. recessive alleles, homozygous vs. heterozygous genotypes, Punnett squares, and phenotypic probabilities.

Let’s go through each question and explain the correct answers and reasoning.

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## Question 1: Homozygous (Ho) or Heterozygous (He)?

Genotypes:

- TT → Ho (same alleles)
- Bb → He (different alleles)
- DD → Ho
- Ff → He
- tt → Ho
- dd → Ho
- Dd → He
- ff → Ho
- Tt → He
- bb → Ho
- BB → Ho
- FF → Ho

✔ Correctly labeled in your image.

> Which of the genotypes in #1 would be considered purebred?
→ Purebred = homozygous (identical alleles). So: TT, DD, tt, dd, ff, bb, BB, FF

> Which of the genotypes in #1 would be hybrids?
→ Hybrid = heterozygous (different alleles). So: Bb, Ff, Dd, Tt

✔ Your answers: “All of the homozygous.” and “All of the heterozygous.” — Perfect!

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## Question 2: Phenotype from Genotype (SpongeBob)

Given:
- Yellow body (Y) is dominant over blue (y)
- Square shape (S) is dominant over round (s)

So:

| Genotype | Phenotype |
|----------|---------|
| YY | yellow |
| Yy | yellow |
| yy | blue |
| SS | square |
| Ss | square |
| ss | round |

✔ Your answers are correct!

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## Question 3: Genotypes for Patrick’s Traits

Given:
- Tall head (T) is dominant over short (t)
- Pink body (P) is dominant over yellow (p)

So:

> Tall = can be TT or Tt (since dominant trait shows with at least one dominant allele)
> Short = must be tt (only way recessive trait appears)

> Pink body = PP or Pp
> Yellow body = pp

✔ Your answers are correct!

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## Question 4: SpongeBob & SpongeSusie Cross

> SpongeBob is heterozygous for square shape → genotype = Ss
> SpongeSusie is round → genotype = ss (recessive phenotype = homozygous recessive)

Punnett Square:

```
| S | s
-----|------|-----
s | Ss | ss
s | Ss | ss
```

✔ Your Punnett square is correctly filled.

A. Possible genotypes & phenotypes:

- Genotypes: Ss, ss
- Phenotypes: Square (Ss), Round (ss)

✔ Correct.

B. Chance of square shape?

→ 2 out of 4 = 1/2 or 50%

✔ Correct.

C. Chance of round shape?

→ 2 out of 4 = 1/2 or 50%

✔ Correct.

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## Question 5: Patrick & Patti Cross

> Both are heterozygous for pink body color → genotype = Pp

Punnett Square:

```
| P | p
-----|------|-----
P | PP | Pp
p | Pp | pp
```

✔ Your Punnett square is correct.

A. Possible genotypes & phenotypes:

- Genotypes: PP, Pp, pp
- Phenotypes: Pink (PP, Pp), Yellow (pp)

✔ Correct.

B. Chance of pink body?

→ 3 out of 4 boxes = PP, Pp, Pp → 3/4 or 75%

✔ Correct.

C. Chance of yellow body?

→ 1 out of 4 = pp → 1/4 or 25%

✔ Correct.

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## ✔ Final Summary:

All your answers on this worksheet are correct! You’ve demonstrated a solid understanding of:

- Homozygous vs. heterozygous
- Dominant vs. recessive traits
- How to determine phenotype from genotype
- How to set up and interpret Punnett squares
- Calculating probabilities of offspring traits

This is a great foundational exercise in Mendelian genetics — using fun characters makes it engaging and memorable!

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Tip for future problems: Always double-check which trait is dominant (given in the problem), and remember that recessive traits only show if *both* alleles are recessive.

Keep up the great work! 🧬🐙