Download Name Bikini Bottom Genetics Worksheet #3 Dihybrid Crosses Use

Name ___________________________
Bikini Bottom Genetics
Worksheet #3
Dihybrid Crosses
Use the chart to identify the genotypes of the following
traits:
1. Heterozygous round eyes, blue body
________
2. Hybrid eye shape, purebred roundpants
________
Trait
Body Shape
Body Color
Eye Shape
Nose Style
Dominant Allele
Squarepants (S)
Yellow (Y)
Round (R)
Long (L)
Recessive Allele
Roundpants (s)
Blue (y)
Oval (r)
Stubby (l)
3. Purebred roundpants, heterozygous long nose ________
4. SpongeBob’s aunt, who is a roundpants, has a cute stubby nose. She has finally found the sponge of her
dreams and is ready to settle down. Her fiancé always comments on how adorable her nose is (he says it
reminds him of his mother’s – aww, how sweet!). They wonder what the chances are of that trait being
passed on. Her fiancé is a purebred squarepants and is a hybrid for his long nose.
A. Identify the genotypes of the aunt and her fiancé.
Aunt = Roundpants, Stubby Nose = ________ Fiancé = Purebred Squarepants, Long Nose = ________
B. What are the possible gamete combinations for each person?
Aunt = ______________________________ Fiancé = ______________________________
C. What are the possible genotypes for their children? ______________________________________
5. As we know, SpongeBob is heterozygous for his yellow body color and his squarepants, while his wife
SpongeSusie is blue and has roundpants. Use this information to answer the following questions.
A. Give the genotypes for each.
SpongeBob = __________________ SpongeSusie = _______________
B. What are the possible gamete combinations for each person?
SpongeBob = __________________ SpongeSusie = __________________
C. Complete the Punnett square below based on the information provided in #5.
_____________ _____________ _____________ _____________
_____________
_____________
_____________
_____________
D. Answer the questions based on your Punnett square. Express your answer as a reduced fraction.
What is the chance of a blue baby?
What is the chance of a baby with blue roundpants?
What is the chance of a baby with squarepants?
What is the chance of a baby that has both recessive traits?
_____
_____
_____
_____
6. In starfish, pink body color (P) is dominant to orange (p), and thick eyebrows (T) are dominant over thin
(t) ones. Patrick, who is heterozygous for body color but purebred for thick eyebrows, has met Patti,
who is recessive for both traits.
A. What is Patti’s phenotype? _______________________________
B. Is it possible for the new couple to have offspring that resemble their mother? Explain.
C. Before Patrick commits to this relationship, he would like to guarantee that his offspring would have his
thick eyebrows as he thinks they make him smarter! You need to provide evidence for or against the
marriage with regards to eyebrows ONLY.
Incomplete Dominance
SpongeBob loves growing flowers for his pal Sandy! Her favorite flowers, Poofkins, are found in red (PR), blue
(PB), and purple. Use the information provided and your knowledge of incomplete dominance to complete
each section below.
7. What would happen if SpongeBob crossed a Poofkin with red flowers with a Poofkin with blue flowers?
Complete the Punnett square to determine the chances of each flower color.
A. Give the genotypes and phenotypes for the offspring.
B. What percentage of the plants would have red flowers?
_____%
C. What percentage of the plants would have purple flowers?
_____ %
D. What percentage of the plants would have blue flowers?
_____ %
8. What would happen if SpongeBob crossed two Poofkins with purple flowers? Complete the Punnett
square to show the probability for each flower color.
A. Give the genotypes and phenotypes for the offspring.
B. What percentage of the plants would have red flowers?
_____%
C. What percentage of the plants would have purple flowers?
_____ %
D. What percentage of the plants would have blue flowers?
_____ %
9. What would happen if SpongeBob crossed a Poofkin with purple flowers with a Poofkin with blue flowers?
Complete the Punnett square to show the probability for plants with each flower color.
A. Give the genotypes and phenotypes for the offspring.
B. If SpongeBob planted 100 seeds from this cross, how many should he expect
to have of each color?
Purple flowers - ______ Blue flowers - ______ Red flowers - ______
Blood Types – Codominance and Multiple Alleles
10. Tell whether the following blood genotypes are homozygous (Ho) or heterozygous (He).
IAIA ____
ii ____
IBi ____
IBIB ____
IAIB ____
IAi____
11. Determine the blood type phenotype for each genotype:
IAIA ____
ii ____
IBi ____
IBIB ____
IAIB ____
IAi____
12. For each blood type phenotype, give the genotypes possible:
Type A: __________
Type B __________
Type O __________
Type AB __________
13. Sandy Squirrel met Stewart Squirrel at the water chestnut festival. They fell in love. Sandy is blood type
AB & Stewart is blood type O.
Sandy Squirrel’s genotype:
________
Stewart Squirrel’s genotype ________
Complete the Punnett square to show the possible
blood genotypes of their children.
What is the possibility of a baby squirrel with blood type O?
____ %
What is the possibility of a baby squirrel with blood type AB?
____ %
What is the possibility of a baby squirrel with blood type A?
____ %
What is the possibility of a baby squirrel with blood type B?
____ %
Explain why none of the offspring are expected to have the same blood type as either parent.
14. Pearl the whale had a horrible accident at cheerleading practice and needed a blood transfusion. So she
needed to find out her possible blood type. Her dad, Mr. Krabbs is homozygous for blood type A and her
mom is heterozygous for blood type B.
Mr. Krabbs’s genotype: ____
Mrs. Krabbs’s genotype: ____
Complete the Punnett square to show Pearl’s possible blood type(s).
What is the possibility of Pearl having blood type O?
____ %
What is the possibility of Pearl having blood type AB?
____ %
What is the possibility of Pearl having blood type A?
____ %
What is the possibility of Pearl having blood type B?
____ %
Sex Linked Traits
15. Tell whether or not the following carry or show the sex-linked recessive krabby-blindness trait. Also tell
whether the individuals are male or female.
(Remember that since most sex-linked traits are recessive, the person who shows the trait can have no X’s
with big superscripted letters. So, if a male carries the trait, he must also show the trait.)
XKXk
XkXk
XKY
XKXK
XkY
Carrier? (Y or N)
Has Trait? (Y or N)
Male or Female? (M or F)
16. Why are there more males than females with the krabby-blindness trait?
17. How can a female inherit a sex-linked trait? Give an example to support your explanation.
18. Fathers do not pass sex-linked traits to their sons. Why not?
19. A krabby-blind whale has married Pearl who has normal vision. One of their two sons is also colorblind.
What are the genotypes of the parents? How do you know?
Before you begin the following problem, remember that you set up the problems with the mom & dad sex
chromosomes, and then give them the appropriate superscripts, depending on their genotypes.
20. In sponges, there exists a sex-linked recessive disorder that causes a sponge to have tiny pores. (XP =
normal pores, Xp = recessive small pores). SpongeBob & his true love SpongeSusie are planning to have
baby sponges. SpongeBob has the disorder & Susie is a carrier.
SpongeBob’s genotype:
_______
SpongeSusie’s genotype:
_______
X
X
Make a Punnett square to show the possible genotypes of their children.
What percentage of their sons will have the disorder?
____
What percentage of their sons will be normal?
____
What percentage of their daughters will have the disorder?
____
What percentage of their daughters will be normal but carriers? ____
What percentage of their daughters will be normal non-carriers? ____
Y
X