Sponge Bob Genetics Punnett Square Practice worksheet | Live ... - Free Printable

Let’s go step by step through each question. We’ll use basic genetics rules:
- Homozygous (Ho) = two same letters (like TT or tt)
- Heterozygous (He) = two different letters (like Tt)
- Purebred = homozygous (same alleles)
- Hybrid = heterozygous (different alleles)
- Dominant trait shows up if at least one capital letter is present
- Recessive trait only shows up if both letters are lowercase

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Question 1:

Genotypes:
- TT → Ho (homozygous)
- Bb → He (heterozygous)
- DD → Ho
- Ff → He
- tt → Ho
- dd → Ho
- Dd → He
- ff → Ho
- Tt → He
- bb → Ho
- BB → Ho
- FF → Ho

Which are purebred? → All the homozygous ones:
TT, DD, tt, dd, ff, bb, BB, FF

Which are hybrids? → All the heterozygous ones:
Bb, Ff, Dd, Tt

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Question 2:

Yellow body color is dominant to blue → Y = yellow, y = blue
Square shape is dominant to round → S = square, s = round

YY → Yellow body
Yy → Yellow body (because Y is dominant)
yy → Blue body

SS → Square shape
Ss → Square shape (because S is dominant)
ss → Round shape

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Question 3:

Tall head (T) dominant to short (t)
Pink body (P) dominant to yellow (p)

Tall = could be TT or Tt (since T is dominant)
Short = must be tt (only way recessive shows)

Pink body = PP or Pp
Yellow body = pp

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Question 4:

SpongeBob is heterozygous for square shape → genotype = Ss
SpongeSusie is round → round is recessive → genotype = ss

Punnett Square:

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

Possible genotypes: Ss, ss
Possible phenotypes: Square (Ss), Round (ss)

Chances of square shape: 2 out of 4 → 50%
Chances of round shape: 2 out of 4 → 50%

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Question 5:

Patrick and Patti are both heterozygous for pink body → genotype = Pp each

Punnett Square:

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

Possible genotypes: PP, Pp, pp
Possible phenotypes: Pink (PP, Pp), Yellow (pp)

Chances of pink body: 3 out of 4 → 75%
Chances of yellow body: 1 out of 4 → 25%

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Final Answer:

1.
TT – Ho
Bb – He
DD – Ho
Ff – He
tt – Ho
dd – Ho
Dd – He
ff – Ho
Tt – He
bb – Ho
BB – Ho
FF – Ho

Purebred: TT, DD, tt, dd, ff, bb, BB, FF
Hybrids: Bb, Ff, Dd, Tt

2.
YY – Yellow
Yy – Yellow
yy – Blue
SS – Square
Ss – Square
ss – Round

3.
Tall = TT or Tt
Short = tt
Pink body = PP or Pp
Yellow body = pp

4.
A. Genotypes: Ss, ss → Phenotypes: Square, Round
B. Square: 2 out of 4 or 50%
C. Round: 2 out of 4 or 50%

5.
A. Genotypes: PP, Pp, pp → Phenotypes: Pink, Yellow
B. Pink: 3 out of 4 or 75%
C. Yellow: 1 out of 4 or 25%