Warm ups:
1. What does homozygous mean?
2. A heterozygous person who is tall has what
genotype?
a. Tt
b. tall
c. Short
d. TT
3. A father is homozygous for blue eyes. (B =
brown, b= blue) What is his genotype?
a. Blue
b. brown
c. bb
d. BB
Bikini Bottom Genetics
Punnett Square Problems #2
One of SpongeBob’s cousin,
SpongeBillyBob, recently met a cute
squarepants gal, SpongeGerdy, at a local
dance and fell in love. Use your
knowledge of genetics to answer the
questions below.
1. If SpongeGerdy’s father is hybrid squarepants and
her mother is a roundpants, what is her genotype?
Complete the punnett square below to show the possible
genotypes that would result to help you determine
Gerdy’s genotype. (S = squarepants, s = roundpants)
G’s father
S
Ss
= _____
ss
G’s mother = ____
Gerdy’s genotype
= ____________
Ss
s
Ss
ss
s
Ss
ss
2. Spongebob BillyBob =
Ss
s
3. Complete the punnett square to show the possibiltiites
that would result if Billy Bob and Gerdy had children. (S
= squarepants, s = roundpants)
S
Ss
Billy Bob = _____
Ss
Gerdy = ____
s
S
SS
Ss
s
Ss
s s
75 % squarepants
_____
25 % roundpants
_____
_____
50 % purebred
50 % hybrid
_____
4. SpongeBob’s aunt and uncle, SpongeWilma and
SpongeWilbur, have the biggest round eyes in the
family. Wilma is believed to be heterozygous for her
round eye shape, while Wilbur’s family brags that they
are a pure line. (R = round eyes r = oval eyes)
R
Rr
Wilma = _____
RR
Wilbur = ____
r
R
RR
Rr
RR
Rr
100 % round eyes
_____
_____
% oval eyes
0
50
_____ % homozygous
50
_____
% heterozygous
R
5. SpongeBob’s aunt is famous around town for her itty, bitty
stubby nose! She recently met a cute squarepants fellow
who also has a stubby noes, which is a recessive trait.
Would it be possible for them to have child with a regular
long nose? Why or why not? Create a punnett square to
help you answer this question.
(L = long nose
l = stubby nose)
llll
Aunt = _____
l
l
Cute guy = ____
l
0
_____
% long nose
100
_____ % stubby nose
100 % homozygous
_____
0
_____
% heterozygous
l
ll
ll
ll
ll
6. SpongeBob’s mother is so proud of her son and his new wife,
SpongeSusie, as they are expecting a little sponge. She
knows that they have a 50% chance of having a little
roundpants, but is also hoping the new arrival will be blue (a
recessive trait) like SpongeSusie and many members of her
family. If SpongeBob is heterozygous for his yellow body
color, what are the chances that the baby sponge will be
blue? (Y = yellow, y = blue)
Yy
Spongebob = ___
yy
Susie = ____
Y
y
_____ % yellow
50
50 % blue
_____
50
_____ % homozygous
50
_____ % heterozygous
y
Yy
yy
Yy
yy
y