Name:_______________________________________________________ Date:___________
Bikini Bottom Genetics
Use the information for SpongeBob’s traits below to complete the genetics problems.
Trait 
Mode of Inheritance 
Possible Phenotypes 

Body Shape 
Sexlinked 
Squarepants (X^{S}) 
Roundpants (X^{s}) 

Body Color 
Incomplete Dominance 
Blue (B) 
Green 
Yellow (B’) 
Eye Shape 
Multiple Alleles 
Round (I^{R}) 
Oval (I^{O)} 
Square (i) 
Nose Style 
Incomplete Dominance 
Long (L) 
Medium 
Stubby (L’) 
Hole Size 
Codominance 
Big holes (B) 
Duel holes 
Small holes (S)

Note: Round and oval are codominant. A sponge with an I^{R} allele and an I^{O} allele have one round eye and one oval eye and are referred to a mixed eyed. Square is recessive to both round and oval.
1. One of SpongeBob’s cousins, SpongeBillyBob, recently met a cute squarepants gal, SpongeGerty at a local dance and fell in love. SpongeGerty’s father is a squarepants and her mother is a roundpants. Use your knowledge of genetics to answer the questions below.
a. What is SpongeGerty’s father’s genotype? ________________
b. What is SpongeGerty’s mother’s genotype? _______________
c. Complete the Punnett square.




Phenotypic Ratio:
Genotypic Ratio:
d. What is SpongeGerty’s genotype? __________________
2. SpongeBillyBob is a squarepants shape.
a. What is SpongeBillyBob’s genotype? _________________
b. Complete the Punnett square to show the possibilities that would results if SpongeBillyBob and SpongeGerty had children.




Phenotypic Ratio:
Genotypic Ratio:
c. What is the probability (percentage) that they will have a daughter with squarepants? _______
d. What is the probability (percentage) that they will have a daughter with roundpants? _______
e. What is the probability (percentage) that they will have a son with squarepants? ___________
3. SpongeBob’s mother is so proud of her son and his new wife, SpongeSusie, as they are expecting a little sponge. She is hoping the new arrival will be blue like SpongeSusie and many members of her family.
a. Complete the Punnett square to show the probability that the baby sponge will be blue.




Phenotypic Ratio:
Genotypic Ratio:
b. What is the probability that the new baby sponge will be blue? ____________
c. What color will the new baby sponge be? ____________________
4. SpongeBob’s aunt is famous around town for her itty, bitty stubby nose! She recently met a cute squarepants fellow with a medium nose. Would it be possible for them to have a child with a regular long nose?
a. Complete the Punnett square to show the probability that they can have a child with a long nose.




Phenotypic Ratio:
Genotypic Ratio:
b. What is the probability (percentage) that they will have a child with a long nose? _______
c. What is the probability (percentage) that they will have a child with a medium nose? _______
d. What is the probability (percentage) that they will have a child with an itty, bitty stubby nose? ___________
5. SpongeBob’s aunt, SpongeWilma, has the biggest round eyes in the family. Wilma is believed to be heterozygous for her round eye shape. SpongeBob’s uncle, SpongeWilbur, has oval eyes and he is heterozygous as well.
a. Complete the Punnett square to show the possibilities that would result if SpongeWilma and SpongeWilbur had children.




Phenotypic Ratio:
Genotypic Ratio:
b. What is the probability (percentage) that they will have a child with round eyes? _______
c. What is the probability (percentage) that they will have a child with oval eyes? __________
d. What is the probability (percentage) that they will have a child with square eyes? _________
e. What is the probability (percentage) that they will have a child with mixed eyes? _________
6. SpongeBob’s sister, SpongeBetty, only big holes and SpongeBob’s brother, SpongeBurt, only has small holes. SpongeBob has duel holes (both big and small holes).
a. Complete the Punnett square to show the genotypes of SpongeBob’s parents.




Phenotypic Ratio:
Genotypic Ratio:
b. What is SpongeBob’s mom’s genotype? __________________
c. What is SpongeBob’s mom’s phenotype? _________________
d. What is SpongeBob’s dad’s genotype? __________________
e. What is SpongeBob’s dad’s phenotype? _________________
7. Roundpants is a recessive sexlinked trait. Label the following pedigree for SpongeBob’s family.