3.
Set up a punnett square using the following information:
• Dominate allele for black fur in guinea pigs = B
• Recessive allele for white fur in guinea pigs =b
• Dominate allele for rough fur in guinea pigs =R
• Recessive allele for smooth fur in guinea pigs = r
• Cross a heterozygous parent (BbRr) with a heterozygous parent (BbRr)
4. Using the Punnett square in question #3:
a. What is the probability of producing guinea pigs with black, rough fur? Possible
genotype(s)?
b. b. What is the probability of producing guinea pigs with black, smooth fur? Possible
genotype(s)?
c. c. What is the probability of producing guinea pigs with white, rough fur? Possible
genotype(s)?
d. d. What is the probability of producing guinea pigs with white, smooth fur? Possible
genotype(s)?
Black fur = B_ BbRr x BbRr
White fur = bb
Rough fur = R_
Smooth fur = rr
BbRr x BbRr Parent R r Parent R r
2 1
2x2=4
B BR Br B BR Br
2x2=4
4x4=16 b bR br b bR br
a. Black rough fur BR bR Br br
Trait B b
B_R_ = 9
BR BBRR BbRR BBRr BbRr 1
BBRR = 1
BbRR = 2 B BB Bb
BBRr = 2 bR BbRR bbRR BbRr bbRr
b Bb bb
BbRr = 4
Br BBRr BbRr BBrr Bbrr
GR: 1:2:1
b. Black smooth fur br BbRr bbRr Bbrr bbrr PR: 3:1
B_rr = 3
BBrr= 1 Trait R r
Bbrr = 2 2
R RR Rr
c. White rough fur d. White smooth fur
bbR_ = 3 bbrr = 1 r Rr rr
bbRR = 1
bbRr = 2 GR: 1:2:1
PR: 3:1
BbRr x BbRr = 16 Allele R r
R r
combination
2 2 2 2 R RR Rr
B BR Br r Rr rr
B b
B BB Bb b bR br
b Bb bb
Traits
BR bR Br br
Combination
BR BBRR BbRR BBRr BbRr
bR BbRR bbRR BbRr bbRr
Br BBRr BbRr BBrr Bbrr
br BbRr bbRr Bbrr bbrr
BBRR =1 1x1=1
a. B_R_ = 9 BbRR = 2 2x1=2 b. B_rr = 3 BBrr = 1 c. bbR_ = 3 bbRR = 1
3x3 Bbrr = 2 bbRr = 2
BBRr = 2 1x2=2
BbRr = 4 2x2=4 d. Bbrr = 1
In rabbits, gray hair is dominant to white hair. Also in rabbits, black eyes are dominant to
red eyes. These letters represent the genotypes of the rabbits:
1. What are the phenotypes (descriptions) of rabbits that have the following
genotypes?
Ggbb _ gray hair red eyes
ggBB _ white hair black eyes
ggbb _ white hair red eyes
GgBb _ gray hair black eyes
2. A male rabbit with the genotype GGbb is crossed with a female rabbit with the
genotype ggBb. Fill it out and determine the phenotypes and proportions in the
offspring.
How many have gray fur and black eyes? ___1___
How many have gray fur and red eyes? ____1____
How many have white fur and black eyes? ___0_____
How many have white fur and red eyes____0____
GGbb x ggBb = 2
b B b
G Gb g gB gb
Gb
gB GgBb Gray hair black eyes
gb Ggbb Gray hair red eyes
2. A male rabbit with the genotype GGbb is crossed with a female rabbit with the
genotype ggBb. Fill it out and determine the phenotypes and proportions in the
offspring.
How many have gray fur and black eyes? ___1_____
How many have gray fur and red eyes? ____1____
How many have white fur and black eyes? ___0_____
How many have white fur and red eyes____0____
GGbb x ggBb = 2
b gB gb
G Gb Gb GgBb Ggbb Gray hair red eyes
Gray hair Black eyes
g
B gB
b gb
1. In man, assume that spotted skin (S) is dominant over non-spotted skin (s) and that
wooly hair (W) is dominant over non-wooly hair (w). Cross a marriage between a
heterozygous spotted, non-wooly man with a heterozygous wooly-haired, non-spotted
woman. Give genotypic and phenotypic ratios of offspring.
Spotted skin = S_ Ssww x ssWw = 4 w s
Non-spotted = ss
S Sw W sW
Wooly hair = W_
Non-wooly hair = ww s sw w sw
sW sw
GR:
SsWw = ¼ Sw SsWw Ssww
ssWw = ¼
Ssww = ¼ sw ssWw ssww
ssww = ¼
Spotted skin wooly hair = ¼ GR: 1:1:1:1
Non-spotted skin wooly hair = ¼ PR: 1:1:1:1
Spotted skin non-wooly hair = ¼
Non-spotted skin non-wooly hair = ¼
1. In man, assume that spotted skin (S) is dominant over non-spotted skin (s) and that
wooly hair (W) is dominant over non-wooly hair (w). Cross a marriage between a
heterozygous spotted, non-wooly man with a heterozygous wooly-haired, non-spotted
woman. Give genotypic and phenotypic ratios of offspring.
Spotted skin (S_) w s
Non-spotted (ss) Ssww x ssWw = 4
S Sw W sW
Wooly Hair (W_) 2x1 = 2
Non wooly hair (ww) 1x2 = 2 s sw w sw
2x2 = 4
sW sw
Sw SsWw Ssww GR: 1:1:1:1
PR: 1:1:1:1
sw ssWw ssww
SsWw = Spotted skin wooly hair
ssWw = nonspotted skin wooly hair
Ssww = spotted skin non wooly hair
Ssww = non spotted skin non wooly hair
3. In summer squash, white fruit color (W) is dominant over yellow fruit color (w)
and diskshaped fruit (D) is dominant over sphere-shaped fruit (d).. If a squash plant
true-breeding for white, disk-shaped fruit is crossed with a plant true-breeding for
yellow, sphere-shaped fruit,
White fruit color = W_ D d
WWDD x wwdd = 1
Yellow fruit color = ww
1x1=1
Diskshape = D_ W WD w wd
1x1=1
Sphere shape = dd
1x1=1
wd
WD WwDd
White fruit color Diskshape
3. In summer squash, white fruit color (W) is dominant over yellow fruit color (w)
and diskshaped fruit (D) is dominant over sphere-shaped fruit (d).. If a squash plant
true-breeding for white, disk-shaped fruit is crossed with a plant true-breeding for
yellow, sphere-shaped fruit,
D d
White fruit color = W_
Yellow fruit color = ww
Diskshape fruit = D_ W WD w wd
Sphere-shape = dd
wd
WWDD x wwdd = 1
WD WwDd
Offspring = WwDd = White fruit color diskshape fruit
1 A a 2 A
AaBbCCDDEe x AABbCCDdee
A AA Aa A AA
2x2x1x1x2 = 8
1x2x1x2x1 = 4 a Aa aa a Aa
8x4 = 32 GR: 1:2:1 GR: 1:1
PR: 3:1 PR: 2
Determine the probability of the
following offspring
3 e 4 a
1. AABBCCDdee = 1x1x1x1x1 = 1 E Ee A Aa
2. AabbCCDDEe = 1x1x1x1x1= 1
3. AABbCCDDEe = e ee
4. AaBbCCDdEe
5. AaBBCCDDEe GR: 1:1 GR: 1
6. AabbCCDDEE = 0 PR: 1:1 PR: 1
5 A
A AA
GR: 1
PR: 1
