EXAM 3: KEY
Instructions:
• PRINT your Name and Exam version Number on your Scantron Example: PAULA SMITH, EXAM 2 VERSION 1
• Write your name CLEARLY at the top of every page of the exam.
• You will be given 2 hours to take the exam.
• For each question on the exam, select the best answer. There is only one best answer for each question.
• When you are done, you must hand in the paper exam, all scratch paper,
and your Scantron. Please them in the correct pile for your exam’s version
number. Exams placed in the wrong pile will be graded with the wrong
Scantron key!
1. Homologs separate from one another during a mitosis
b. meiosis I c. meiosis II d. interphase e. pachytene
2. Puzzle is a male calico cat. Which of the following would explain his phenotype?
a. XY
b. XXY
c. X
d. XYY
e. None of the above
3. In guinea pigs, if a pure-breeding male with a solid brown coat is mated to a pure-breeding female with a solid white coat, all the offspring have grey coats. This is an example of
a. overdominance b. incomplete dominance c. codominance
d. X-inactivation e. None of the above
4. In mammals, oogenesis gives rise to.
a. 4 haploid eggs
b. 2 haploid eggs and one polar body c. 3 haploid eggs and one polar body d. 1 haploid egg and 2 polar bodies e. 1 haploid egg and 3 polar bodies
5. If a pure-breeding Australian Shepard with gold eyes is crossed with a pure-breeding partner with blue eyes, all of the offspring have gold eyes. When these offspring are crossed to one another, some have gold eyes, some have blue eyes, and some have green eyes. This is an example of
a. sex-influence
b. incomplete dominance c. codominance
d. epistasis
e. incomplete penetrance
6. In tomato, Y = yellow flowers, y = white flowers; D = dark leaves, d = pale leaves. A dihybrid tomato plant is test crossed with the following results: 456 yellow flowers, pale leaves; 462 white flowers, dark leaves;
38 yellow flowers, dark leaves; 40 white flowers, pale leaves. These data indicate:
a. Flower color is under the control of two genes.
b. One of the dihybrid’s parents had yellow flowers and pale leaves.
c. The genes for flower color and leaf color assort independently.
d. Gene linkage, with a map distance > 50 cM.
e. None of the above
7. Which of the following characters was NOT studied by Mendel?
a. Leaf shape b. Flower position c Flower color d. Seed shape e. Seed color
For questions 8-9 refer to the following:
Grant has inherited a tulip farm from his uncle. Almost all the tulips are pale yellow but he notices that a few have gorgeous golden flowers. Grant crosses two of the golden-flowered plants to each other and gets 89 golden and 30 pale yellow.
8. Grant’s data suggest that
a. flower color is under the control of many genes and the environment b. flower color is inherited according to Mendel’s First Law
c. Grant will never be able to isolate a pure-breeding line of golden flowers d. flower color is controlled by two genes with redundant activity
e. the allele for golden flowers is recessive 9. Grant’s data also suggest that
a. the allele for golden flowers is lethal in homozygotes b. all golden-flowered plants are heterozygous
c. all plants with pale yellow flowers are heterozygous
d. the offspring of a cross between two plants with pale yellow flowers will also have pale yellow flowers
e. plants with golden flowers are rare because they can’t make seeds
10. In honey bees, A = antenna, a = no antenna. A queen with antennae is crossed with a male that lacks antennae. All the offspring are females and they all have antennae. What’s going on?
a. Sex-linkage b. Sex-influence c. Sex-limited d. X-inactivation e. Males are haploid
11. One of Mendel’s great discoveries was that a. genes are located on chromosomes b. mutations can be induced with X-rays
c. some genes don’t assort independently from one another d. genes interact more like cans of paint than like ping pong balls e. None of the above
12. Which of the following would eliminate X-linkage as a possible mode of inheritance?
a. An affected female has an affected mother.
b. An affected female does NOT have an affected mother.
c. An affected female has an affected father.
d. An affected female does NOT have an affected father.
e. None of the above
13. Mary is shocked when she learns that she has testicular cancer! What genetic phenomenon can explain this?
a. Haploidy b. X-inactivation
c. Androgen insensitivity d. Sex reversal mutant e. X-linkage
For questions 14-15, refer to the following paragraph:
In kangaroos, P = wide pouch, p = narrow pouch; E = big ears, e = little ears. A dihybrid kangaroo is test-crossed.
For each of the data sets, indicate the correct explanation.
14. 12 wide pouch, big ears; 8 narrow pouch, big ears; 9 wide pouch, little ears; 13 narrow pouch, little ears.
(p = 0.45).
a. Independent assortment
b. Linked genes located approximately 60 cM apart c. Linked genes located approximately 40 cM apart d. Narrow pouch is semi-lethal
e. Little ears is semi-lethal
15. 36 wide pouch, big ears; 49 narrow pouch, big ears; 52 wide pouch, little ears; 34 narrow pouch, little ears. (p = 0.039).
a. Independent assortment
b. Linked genes located approximately 60 cM apart c. Linked genes located approximately 40 cM apart d. Narrow pouch is semi-lethal
e. Little ears is semi-lethal
16. Male Idaho Hummingbirds have bright, iridescent red wings. Females have dull-colored wings. Which of the following could cause this sexual dimorphism?
a. Z-linkage b. W-linkage
c. The allele for red wings is dominant in males and recessive in females.
d. The allele for red wings is only expressed in males.
e. None of the above 17. The “two-hit hypothesis” explains
a. what happens when a trait is influenced by two genes b. why some families have a high incidence of cancer c. why Mendel observed a 9:3:3:1 ratio in his F2s
d. why heterozygotes are the most common genotype in the F2 generation of a monohybrid cross e. independent assortment
18. In Green-bellied snakes, G = green belly, g = brown belly. When a pure-breeding green-bellied snake is crossed to a brown-bellied one, all of the offspring have green and brown stripes. This is an example of a. Codominance
b. Incomplete dominance c. Overdominance d. Complete dominance e. Underdominance
19. The allele for color-blindness is located on the X chromosome. Carissa is color-blind in one eye but not in the other. Which of the following might explain this?
a. Epistasis b. X-inactivation
c. Incomplete penetrance d. Overdominance
e. Dominant semi-lethal allele
20. Mendel performed his famous experiments around the same time a. that James Watson was born (1928)
b. that Thomas Morgan was born (1866) c. as the American Revolution (1775-1783) d. that King Henry VIII of England died (1547) e. that protohumans began to walk upright
21. In Northeastern Finches, “ff” chicks are born without feathers and die of cold soon after hatching. Despite its deleterious phenotype, the “f” allele is very common and about 10% of Northeastern Finches are heterozygous. This high level of heterozygosity can be explained by
a. variable expressivity b. semi-lethal allele c. overdominance d. gene linkage e. Mendel’s First Law
22. How many gametes are produced by an orchid plant with the genotype GgHhTT?
a. 1
b. 2
c. 4
d. 6
e. 8
23. If you cross a trihybrid pea plant with a tester, what fraction of the offspring will be trihybrid?
a. 1/2 b. 1/4 c. 1/8 d. 3/8
e. 9/16
24. Evan is 45 years old and pattern bald. He reads that the castrati were protected against pattern baldness because they didn’t have testicles. Oddly, Evan cares more about his hair than his testicles, so he has his testicles surgically removed. What’s true of Evan now?
a. He has a full head of hair.
b. He has a lovely soprano singing voice.
c. He is extremely hairy all over, not just on his head.
d. He has two X chromosomes.
e. He is a middle-aged pattern-bald man with no testicles.
25. Wild iris comes in three shades of purple: lavender, mauve, and heliotrope. If two pure-breeding plants are crossed, the F1s are mauve. In the F2s, mauve is the most common, followed by heliotrope and then lavender. Which of the following is probably true?
a. Pure-breeding plants are either mauve or lavender.
b. Dihybrids are heliotrope.
c. Testers are heliotrope.
d. One gene controls the trait with two incompletely dominant alleles.
e. None of the above
26. When Mendel died:
a. He was famous.
b. His great-grandchildren tried to steal his pea plants.
c. He left behind meticulous records of his experiments.
d. He was sad because he’d never published his work.
e. None of the above
27. Karina has cystic fibrosis and is hospitalized for lung infections on a regular basis. Her sister, Clara, also has the disease. However, Clara’s symptoms are easily controlled at home (she is rarely hospitalized). What explains the difference in the two girls’ phenotypes?
a. Variable penetrance b. Variable expressivity c. Incomplete penetrance d. Incomplete expressivity e. Overdominance
28. A mouse has the genotype HHTt. Which of the following gametes does it produce?
a. HH
b. Tt
c. HT
d. hT
e. All of the above
29. In humans, homologs differ (on average) about 1 in every ______ base-pairs.
a. 10
b. 100
c. 1,000 d. 10,000 e. 100,000
30. In lobster, Y = yellow, y = wild-type. Two Yy lobsters are crossed with the following results: 155 yellow : 62 wild-type. What explains this outcome?
a. All yellow lobsters are heterozygous.
b. Some of the yellow offspring died before they could be counted.
c. Some of the wild-type offspring died before they could be counted.
d. Yellow is the most common phenotype in the population.
e. None of the above
31. “Let’s Zip Parka During Dance” refers to:
a. Mendel’s First Law b. Mendel’s Second Law c. Mitosis
d. Prophase I e. Prophase II
32. Why are higher eukaryotes (like humans) committed to sexual reproduction?
a. It increases the frequency of beneficial mutations.
b. It selects for mutations that are beneficial.
c. It increases variation to prevent infection and parasitism by microorganisms.
d. It enables individuals to pass 100% of their genes to the next generation.
e. Because it’s fun.
33. The correct order of stages in mitosis is
a. prophase, metaphase, anaphase, telophase b. prophase, anaphase, metaphase, telophase
c. interphase, prophase, metaphase, anaphase, telophase d. telophase, metaphase, prophase, anaphase
e. anaphase, metaphase, telophase, prophase
34. Which of the following is characteristic of a sex-influenced trait?
a. It’s seen much more often in one sex than another.
b. Hormones are affecting its expression.
c. The allele for the trait is dominant in one sex and recessive in the other.
d. A person can inherit the allele from either parent.
e. All of the above
35. Which of the following is characteristic of the inheritance of holandric traits?
a. Affected males always have affected fathers.
b. Affected females always have affected fathers.
c. They are only observed in ants and bees.
d. They are only observed in the birds and the bees.
e. They skip generations.
36. The horn length of unicorns ranges from 45 cm to 102 cm. When the horns of hundreds of unicorns are measured, the distribution forms a bell curve like that shown below. The y axis represents the number of unicorns with each measured horn length.
These data indicate that horn length in unicorns is controlled by a. A single gene with only one allele
b. A single gene with two alternative alleles c. Two genes with redundant functions
c. The same genetic mechanism that controls coat color in Labrador Retrievers d. Many genes
Horn length (cm)
