Download Unit 1 Review Answer Key 1. Define the following terms: a

Unit 1 Review
Answer Key
1. Define the following terms:
a. Genotype is the genetic makeup of an individual. Usually genes are
represented by letters (e.g. BB=Present, Bb= Present, bb= Absent).
b. Phenotype is the observable characteristics of a person determined by their
genotype. Usually represented by letters (e.g. BB=Brown, Bb=Brow, bb=blue).
c. The dominant allele masks the expression (phenotype) of another allele at the
same locus. It is usually represented with an uppercase letter.
d. The recessive allele is the expression (phenotype) hidden by another allele at
the same locus; the allele phenotype is only seen in a homozygous genotype. It
is usually represented with a lowercase letter.
e. Homozygous means that identical alleles for the gene of interest are present
on both homologous chromosomes.
f. Heterozygous means that two different alleles for the gene of interest are
present on each of the homologous chromosomes.
g. Parental generation is the first generation that is mated.
h. F1 generation is the resulting offspring of the parental generation (F1 = first
filial).
i. Test cross is a test that determines the genotype of an organism for a particular
trait.
j. Punnett square is a diagram that is used to predict the probabilities of the
phenotype and/or genotype of offspring.
k. Monohybrid cross is a cross that examines the genotypes or phenotypes
produced concerning one trait.
l. Dihybrid cross is a cross that examines the genotypes or phenotypes produced
concerning two traits
2. If the male parent had the following genotypes, what allele would his gametes
(sperm) contain?
a. AA: 100% of sperm would contain the allele A.
b. Aa: 50% of sperm would contain the allele A; 50% would contain the allele a.
c. aa: 100% of sperm would contain the allele a.
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3. If the male parent had the following genotypes, what alleles would his gametes
(sperm) contain?
a. AABB: 100% of sperm would contain the alleles AB.
b. AaBb: 25% of sperm would contain the alleles AB; 25% would contain the
alleles Ab; 25% of sperm would contain the allele aB; 25% of sperm would
contain the allele ab.
c. aabb: 100% of sperm would contain the allele ab.
d. AABb: 50% of sperm would contain the allele AB; 50% of sperm would contain
the allele Ab.
4. Determine if the following genotypes are homozygous dominant, homozygous
recessive, or heterozygous.
a. HH: homozygous dominant
b. Aa: heterozygous
c. AA: homozygous dominant
d. hh: homozygous recessive
e. Hh: heterozygous
f. Bb: heterozygous
g. bb: homozygous recessive
h. BB: homozygous dominant
5. If purple (P) is dominant to white flowers (p), then what is the phenotype for the
following individuals?
a. PP: purple
b. Pp: purple
c. pp: white
6. If purple (P) is dominant to white flowers (p) and Smooth (S) petals are dominant to
wrinkly (s) petals, then what is the phenotypes for the following individuals?
a. PPSS: purple, smooth
b. PPSs: purple, smooth
c. PPss: purple, wrinkly
d. PpSS: purple, smooth
e. PpSs: purple, smooth
f. Ppss: purple, wrinkly
g. ppSS: white, smooth
h. ppSs: white, smooth
i. ppss: white, wrinkly
7. Fill in the missing portions (indicated with “?”) of the Punnett square of a cross
between individuals with genotypes AA and AA.
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8. Fill in the missing potions (indicated with “?”) of the Punnett square of a cross
between individuals with genotypes aa and aa.
9. Fill in the missing portions (indicated with “?”) of the Punnett square of a cross
between individuals with genotypes Aa and Aa.
10. Fill in the entire Punnett square of a cross between individuals with genotypes Bb
and BB.
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11.
Use the Punnett square below and the following information: Long (L) is
dominant to short (l). Answer the following questions.
a. What is the predicted genotypic ratio of the offspring, expressed by listing
dominant before recessive? 4:0
b. What is the predicted phenotypic ratio of the offspring, expressed by listing
dominant before recessive? 4:0
c. What is the predicted proportion of offspring that has long hair? 4/0
d. What is the predicted proportion of offspring that has short hair? 0/4
e. What is the predicted percentage of offspring that has long hair? 100%
f. What is the predicted percentage of offspring that has short hair? 0%
12. Use the Punnett square below and the following information: Long (L) is dominant to
short (l). Answer the following questions.
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a. What is the predicted genotypic ratio of the offspring, expressed by listing
homozygous dominant before heterozygous before homozygous recessive?
1:2:1
b. What is the predicted phenotypic ratio of the offspring, expressed by listing
dominant before recessive? 3:1
c. What is the predicted proportion of offspring that has long hair? 3/4
d. What is the predicted proportion of offspring that has short hair? 1/4
e. What is the predicted percentage of offspring that has long hair? 75%
f. What is the predicted percentage of offspring that has short hair? 25%
13. Use the Punnett square below and the following information: Long (L) is dominant to
short (l). Answer the following questions.
a. What is the predicted genotypic ratio of the offspring, expressed by listing
homozygous dominant before heterozygous before homozygous recessive?
0:4:0
b. What is the predicted phenotypic ratio of the offspring, expressed by listing
dominant before recessive? 4:0
c. What is the predicted proportion of offspring that has long hair? 4/4
d. What is the predicted proportion of offspring that has short hair? 0/4
e. What is the predicted percentage of offspring that has long hair? 100%
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f. What is the predicted percentage of offspring that has short hair? 0%
14. Fill in the missing portions (indicated with “?”) of the Punnett square of a cross
between individuals with genotypes GGHH and GGHH.
15. Fill in the missing portions (indicated with “?”) of the Punnett square of a cross
between individuals with genotypes GgHh and GgHh.
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16. Fill in the missing portions (indicated with “?”) of the Punnett square of a cross
between individuals with genotypes GGHH and gghh.
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17. Fill in the entire Punnett square of a cross between individuals with genotypes Gghh
and GgHh.
18. Use the Punnett square below and the following information: Brown (B) is dominant
to green (b) and Hairy (H) is dominant to bald (h). Answer the following questions.
a. What are the genotypes of the parents? BbHh x BbHH
b. What are the phenotypes of the parents? Brown/Hairy x Brown/Hairy
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c. What are the genotypes of the F1 generation? BBHH(2), BbHH (2), BBHh (2),
BbHH (2), BbHh (2), bbHh (2), bbHH (2), BbHh (2)
d. What are the phenotypes of the F1 generation? Brown/Hairy and Green/Hairy
BBHH = Brown /hairy
BbHH = Brown /hairy
BBHh = Brown /hairy
BbHH = Brown /hairy
BbHh = Brown /hairy
bbHH = green/hairy
bbHh = green/hairy
19. Which of the following is an example of a “testcross?”
A. An unknown against a homozygous dominant
B. An unknown against an unknown
C. An unknown against a homozygous recessive
D. None of the above
20. If you were conducting a testcross with an unknown individual for one allele and you
found the offspring to be 50% one phenotype and 50% the other, then what was the
genotype of the unknown?
A. Homozygous dominant
B. Heterozygous
C. Homozygous recessive
D. Unknown based on this information
21. If you crossed two pea plants that were heterozygous for pea shape [smooth (S)
dominant to wrinkled (s)] and flower color [purple (P) dominant to white (p)], what
genotypic ratio would you expect?
A. 9:3:3:1
B. 1:1:1:1
C. 1:2:2:4:1:2:1:2:1
D. None of the above
22. Backcrossing can be used to do which of the following?
A. To create an individual that is genetically more like one of its parents
B. To create a completely unique individual
C. To save an endangered species
D. Both A and C
23. If you were to cross a purple flowered individual with the genotype Pp (purple is
dominant to white) with another purple flowered individual with the genotype PP, then
what phenotype ratio would you expect?
A. 100% of the offspring will be purple flowered (1:0).
B. 50% will be purple flowered, and 50% will be white flowered.
C. 100% of the offspring will be white flowered (0:1).
D. None of the above
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24. If you conducted a dihybrid cross for pea color [Green (G) is dominant to yellow (g)]
and plant height [Tall (T) is dominant to short (t)], then what phenotypic ratio would you
expect?
A. 9:3:3:1
B. 1:1:1:1
C. 1:2:2:2:2:1:2:2:1:1
D. None of the above
25. If you cross two ladybugs that have spots and stripes (two codominant traits), then
what would the phenotypic and genotypic ratios be in the offspring (in that order)?
A. 1:2:1 and 3:1
B. 3:1 and 1:2:1
C. 3:1 and 3:1
D. 1:2:1 and 1:2:1
26. If you conduct a testcross with an individual with an unknown genotype that has
green peas and purple flowers (Green-G is dominant to yellow-g and purple-P is
dominant to white-p), then what phenotypic ratio would you expect in your offspring if
your unknown was heterozygous for green and homozygous for purple?
A. 1/2 would be green purple, and 1/2 would be yellow purple.
B. 1/2 would be green purple, and 1/2 would be green white.
C. 1/2 would be green white, and 1/2 would be yellow white.
D. none of the above
27. The Punnett Square was created by Reginald Punnett and will show you which of
the following?
A. The probability of different phenotypes in the next generation
B. The phenotypes of the next generation
C. The genotypes of the next generation
D. All of the above
28. The Principle of Independent Assortment indicates which of the following?
A. When gametes are formed, all traits will be inherited independently.
B. When gametes are formed, unlinked alleles will assort independently.
C. Gametes will contain one copy of each chromosome.
D. Gametes will contain chromosomes that have undergone.
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