1. No category

Name: ______________________________
Date: _____________________
Independent Practice: Punnett Squares
For each of the diagrams below, label the type of dominance that is being demonstrated
(complete dominance, co-dominance, or incomplete dominance).
1. In cocker spaniels the allele for a black coat color (B) is dominant over the
allele for a brown coat color (b). If a brown cocker spaniel is crossed with a
heterozygous black cocker spaniel, which of the following genotypic ratios
can be expected?
A 0 BB: 2 Bb: 2 bb
C 2 BB: 0 Bb: 2 bb
B 1 BB: 2 Bb: 1 bb
D 2 BB: 1 Bb: 0 bb
2. A species of flowers exhibits incomplete dominance between the allele
for red flowers (R) and the allele for white flowers (r) resulting in pink
heterozygotes. If two pink flowers are crossed, what percentage of the
offspring will have pink flowers?
A 100%
B 75%
C 50%
D 25%
3. Tomato plants usually have hairy stems. Hairless stems are present in tomato
plants that are homozygous recessive for this trait. If the stem characteristics are
determined by a single gene, what is the expected outcome of crossing two tomato
plants that are heterozygous for hairy stems?
A 75% hairy stems: 25% hairless stems
C 100% hairless stems
B 100% hairy stems
D 50% hairy stems: 50% hairless stems
4. Humans exhibit co-dominance between the alleles for A and B blood
types (IA and IB respectively). Type O blood (i) is a recessive allele.
A man with type A blood (IA i) is crossed with a woman with type B
blood (IBIB). What is the probability their child will have AB blood?
A⅛
B¼
C½
D¾
5. Humans can have attached earlobes (e) or unattached earlobes (E).
What would be the ratio of phenotypes from a cross between two
people that were heterozygotes for this allele?
A 1 attached : 0 unattached
C 2 attached : 1 unattached
B 1 attached : 3 unattached
D 3 attached : 1 unattached
6. In humans, the allele for dimples (D) is dominant. The allele for not
having dimples (d) is recessive. A woman (DD) and a man (Dd) have
four children. Which of these is the predicted ratio of the children with
dimples to the children without dimples?
A1:0
B1:1
C1:3
D3:1
7. In Analusian chickens, feather color is inherited by incomplete dominance.
If one parent with black feathers (BB) is crossed with a white-feathered parent
(WW), all of the offspring will have blue feathers (BW).What is the percent
chance of producing blue-feathered offspring when crossing a blue-feathered
hen with a white feathered rooster?
A 25%
B 50%
C 75%
D 100%
8. In fruit flies, the gene for red eyes (R) is dominant and the gene for sepia
eyes (r) is recessive. What are the possible combinations of genes in the
offspring of two red-eyed heterozygous flies (Rr)?
A RR only
C rr only
B Rr and rr only
D RR, Rr, and rr only
9. In pigeons, the allele for normal feathers (F) is dominant to the allele for
frizzy feathers (f).
If a purebred, normal-feathered bird (FF) is crossed with a frizzy-feathered
bird (ff), how many different feather phenotypes are possible in the offspring?
A1
B2
C3
D4
10. In humans, the ability to taste PTC (T) is dominant to the allele for
non-tasters (t). If a man that can taste PTC (Tt) has children with a
non-tasting female, what will be the ratio of phenotypes in the offspring?
A 50% tasters and 50% non-tasters
C 100% tasters
B 75% tasters and 25% non-tasters
D 100% non-tasters
11. The table lists the traits for fruit color that exhibits incomplete dominance.
What percentage of offspring are expected to have an orange phenotype
if the parent plants are orange (Rr) and yellow (rr)?
A 25%
C 75%
B 50%
D 100%
For each dihybrid cross shown below, fill in the Punnett squares correctly.
WwRr × wwRr
EeBb × EEbb
NnTt × NnTt
Determine the product of each pair of percentages or fractions.
50% × 50% = ___________
¾ × ¾ = ___________
¼ × ½ = ___________
75% × 50% = ___________
25% × 50% = ___________
25% × 25% = ___________
½ × ½ = ___________
¾ × ½ = ___________
12. Two fruit flies, heterozygous for red eye color (Rr) and yellow body color (Yy), are crossed.
What is the probability the offspring will be homozygous recessive for eye and body color?
A 8 / 16
B 4 / 16
C 1 / 16
D 0 / 16
13. In tomatoes, red fruit (R) is dominant to yellow fruit (r), and tall plants (T) are dominant to
short plants (t). What percentage of offspring from a RRTT x rrtt cross are expected to be RrTt?
A 0%
B 50%
C 75%
D 100%
14. In the 1860s Gregor Mendel performed numerous dihybrid crosses between pea plants.
Dihybrid crosses involve the study of the inheritance patterns related to two different traits. In
guinea pigs the allele for black fur (B) is dominant over the allele for brown fur (b), and the
allele for short fur (F) is dominant over the allele for long fur (f). What percentage of the
offspring from a BbFf x bbff cross would be expected to be heterozygous for both traits?
A 0%
B 25%
C 50%
D 100%
15. In fruit flies the presence of wings (W) is dominant to the absence of wings (w), and red
eyes (R) are dominant to brown eyes (r). A wingless fly that is heterozygous for eye color is
crossed with a fly that is heterozygous for wings and has brown eyes. What is the probability
that the offspring would be homozygous recessive for wings and eye color?
A 100%
B 75%
C 50%
D 25%
16. If several pea plants with the genotype TTYy are crossed with pea plants with the genotype
Ttyy, what percentage of the offspring will be expected to have the TTYy allele combination?
A 25%
B 40%
C 50%
D 75%
17. Colorblindness in humans is a mutation carried on the X chromosome. A man and a woman
with normal vision have a colorblind son. What are the chances their next child will be a
colorblind daughter?
A 100%
B 75%
C 50%
D 0%
18. A woman who is colorblind (XcXc) can expect A 100% of her female offspring to be colorblind
B 100% of her male offspring to be colorblind
C 50% of her female offspring to be colorblind
D 50% of her male offspring to be colorblind
19. Hemophilia is an X-linked recessive trait. In a family, the father is unaffected and the
mother carries only one recessive allele. Which outcome is expected for their offspring?
A All the male offspring would be affected.
B All the female offspring would be affected.
C Half the male offspring would be affected.
D Half the female offspring would be affected.
20. Muscular dystrophy is an X-linked recessive condition that occurs in approximately one of
every 3500 individuals. A woman who is a carrier of muscular dystrophy marries a man who
does not have muscular dystrophy. Which of the following is an expected outcome regarding
the inheritance of muscular dystrophy by their children?
A Twenty-five percent of the sons would be carriers.
B One hundred percent of the daughters would be carriers.
C Fifty percent of the sons would have muscular dystrophy.
D Seventy-five percent of the daughters would have muscular dystrophy.