BIO 121 Exam #1 - Sample
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46 (10 pts.) Place answer below.
Exam 1
Multiple Choice
Identify the letter of the choice that best completes the statement or answers the question.
____ 1. Why is color-blindness more common in males than in females?
a. Because females would have to receive two copies of the recessive color blindness gene to actually express the trait.
b. Because a male only needs to receive the recessive gene from his mother to be color-blind.
c. Because color-blindness is an X-linked trait.
d. All of the above
e. None of the above
____ 2. The offspring of two heterozygous gray-bodied, normal-winged flies should be 50% gray-bodied/normal wings (BbRr) and 50% black-bodied/vestigal wings (bbrr) because these alleles are linked. If a small number, say 15%, of the offspring are instead black-bodied with normal wings, this is most likely the result of:
a. crossing-over.
b. incomplete dominance.
c. codominance.
d. an error in meiosis.
e. mutation.
____ 3. Which of the following represents the possible genotype(s) resulting from a cross between two individuals that are heterozygous (Bb)?
a. BB and Bb
b. BB, Bb, and bb
c. BB only
d. Bb only
e. bb only
____ 4. Two Martians fall in love and marry. One Martian is homozygous for red eyes and the other is heterozygous. The recessive eye color is purple. What are the chances that the alien couple will have a child with red eyes?
a. 1
b. 1/2
c. 1/4
d. 3/4
e. 0
____ 5. Two Martians fall in love and marry. One Martian is homozygous for red eyes and the other is heterozygous. The recessive eye color is purple. What is the probability that they will have a child with purple eyes?
a. 1/1
b. 1/2
c. 1/4
d. 3/4
e. 0
____ 6. The height of F1 pea plants from a cross between parent plants heterozygous for height would be:
a. all short.
b. all tall.
c. 1 tall: 3 short.
d. 2 short: 2 tall.
e. 3 tall: 1 short.
____ 7. Two Martians fall in love and marry. One Martian is homozygous for red eyes and the other is heterozygous. The recessive eye color is purple. What is the probability that the alien couple will have a child that is heterozygous for eye color?
a. 1
b. 1/2
c. 1/4
d. 3/4
e. 0
____ 8. A diploid individual has a maximum of ____________ different alleles for a particular locus.
a. one
b. two
c. four
d. more than four
e. less than one
____ 9. What is the probability that two lizards that are heterozygous for stripes on their tails (Ss) will produce an offspring that is homozygous for no stripes (ss)?
a. 1
b. 1/2
c. 1/4
d. 1/8
e. zero
____ 10. ________________________ refers to multiple independent pairs of genes having similar and additive effects on the same characteristic.
a. Codominance
b. Epistasis
c. Polygenic inheritance
d. Complete dominance
e. Additive dominance
____ 11. Genes that tend to be inherited together are said to be:
a. associated.
b. related.
c. similar.
d. linked.
e. alleles.
____ 12. The principle of independent assortment is violated by:
a. incomplete dominance.
b. mutations.
c. heterozygotes.
d. homozygotes.
e. X-linked genes.
____ 13. What are the predicted phenotypes of the children from the union of a woman who is heterozygous for hemophilia and a man who is normal blood clotting characteristics? (Use the Punnett square to verify your answer.)
a. All normal.
b. 1/2 normal: 1/2 hemophilia
c. 1/4 hemophilia: 3/4 normal
d. 3/4 hemophilia: 1/4 normal
e. All hemophiliacs
____ 14. In a two-point test cross, 36 of the offspring were recombinant types. The remaining 64 offspring were parental types. How many map units separate the two loci?
a. 32
b. 36
c. 64
d. 78
e. 100
____ 15. ____________ are alternative genes that govern the same feature, such as eye color, and occupy corresponding positions on homologous chromosomes.
a. Alleles
b. Loci
c. Homozygotes
d. Coupled traits
e. None of the above
____ 16. The genotype for a pea plant that is homozygous recessive for both height and pea color would be:
a. tt.
b. YY.
c. TtYy.
d. ttyy.
e. TTYY.
____ 17. Mendel's principle of segregation states that:
a. alleles from one parent mask the expression of alleles from the other parent.
b. alleles separate from each other before gametes form.
c. hybrids will express a phenotype intermediate between the two parental phenotypes.
d. true-breeding parents produce offspring of the same phenotype.
e. different loci separate from each other.
____ 18. Using standard conventions for naming alleles, which of the following pairs is correct?
a. Tt - recessive phenotype
b. TT - heterozygous
c. tt - homozygous
d. tt - dominant phenotype
e. All of the above
____ 19. Mating an individual expressing a dominant phenotype, but whose genotype is unknown, with an individual expressing the corresponding recessive phenotype is an example of:
a. a heterozygous cross.
b. an F1 cross.
c. an F2 cross.
d. a parental cross.
e. a test cross.
____ 20. In humans, brown eyes are dominant and blue eyes are recessive. If two brown-eyed individuals have a child with blue eyes, that means:
a. both parents are homozygous for brown eyes.
b. both parents are heterozygous for eye color.
c. there is a 1/4 chance that their second child will have brown eyes.
d. there is a 50/50 chance that their second child will have blue eyes.
e. None of the above
____ 21. A ___________________________ is used to demonstrate the linkage of two genes.
a. monohybrid cross
b. dihybrid cross
c. monohybrid test cross
d. two-allele test cross
e. two-point test cross
____ 22. Which of the following represents the possible genotype(s) resulting from a cross between an individual homozygous for black hair (BB) and a heterozygous (Bb) individual?
a. BB and Bb
b. BB, Bb, and bb
c. BB only
d. Bb only
e. bb only
____ 23. What are the possible phenotypes of the children if the mother has Type A blood and the father has type AB blood? (Use the Punnett square to verify your answer.)
a. all AB
b. 1/2 A: 1/2 B
c. 1/2 A: 1/2 AB
d. 1/2 A: 1/4 B: 1/4 AB
e. Insufficient information is available
____ 24. A brown-eyed couple already has a child with blue eyes. What is the probability that their next child will have blue eyes?
a. 0
b. 1/4
c. 1/2
d. 3/4
e. 1
____ 25. The term dominant" means that:
a. the dominant phenotype shows up at least 50% of the time in the first generation.
b. all members of the F2 generation of a hybrid cross exhibit the dominant phenotype.
c. one allele can mask the expression of another in a hybrid.
d. the dominant phenotype shows up in 100% of the offspring in all generations.
e. the dominant phenotype is more beneficial than the recessive phenotype.
____ 26. When pink-flowered plants were crossed they produced offspring with red, pink, and white flowers in a ratio of 1:2:1. This is an example of:
a. variegation.
b. hybrid vigor.
c. incomplete dominance.
d. epistasis.
e. a polygenic trait.
____ 27. A Barr body in a mammalian female cell represents:
a. an inactivated oocyte.
b. a polar body.
c. a degenerate nucleus.
d. an inactivated X chromosome.
e. an inactivated Y chromosome.
____ 28. Mendel established true-breeding pea plants for certain traits before undertaking his experiments. The term "true-breeding" refers to:
a. genetically pure lines.
b. organisms that have a high rate of reproduction.
c. organisms that will produce identical copies of themselves upon reproduction.
d. organisms that are heterozygous for a given trait.
e. organisms that are homozygous for all possible traits.
____ 29. Why is pattern baldness more common in men than in women?
a. Because the expression of the allele for baldness is influenced by male hormones.
b. Because of epistasis by genes on the Y chromosome.
c. Because females must be heterozygous to express pattern baldness.
d. Because female sex hormones inhibit expression of pattern baldness genes.
e. Because male behavior and lifestyle enhance expression of the pattern baldness gene.
____ 30. Which of the following phenomena is an exception to Mendel's principles?
a. independent assortment of genes
b. random segregation
c. allelic dominance
d. polygenic inheritance
e. None of the above
____ 31. Which of the following represents the possible genotype(s) resulting from a cross between an individual homozygous for black hair (BB) and an individual homozygous for blonde hair (bb)?
a. BB and Bb
b. BB, Bb, and bb
c. BB only
d. Bb only
e. bb only
____ 32. What are the predicted phenotypes of the children from the union of a woman who is heterozygous for hemophilia and a man who is normal blood clotting characteristics? (Use the Punnett square to verify your answer.)
The genotype of a female child from the question would be:
a. XHXH or XHXh.
b. XHXh.
c. XHYH.
d. Hh.
e. HH.
____ 33. A particular gene that controls seed coat color in peas also determines the susceptibility of these peas to a particular disease. This situation is referred to as:
a. variegation.
b. additive dominance.
c. codominance.
d. pleiotropy.
e. incomplete dominance.
____ 34. The phenotype for a pea plant with the genotype TTyy would be:
a. heterozygous.
b. Ty.
c. short with yellow peas.
d. tall with green peas.
e. tall with yellow peas.
____ 35. The physical location of a particular gene on a chromosome is called:
a. an allele.
b. a locus.
c. a trait.
d. linkage.
e. None of the above
____ 36. Calico cats are never male because:
a. recessive genes are not usually expressed on their only X chromosome.
b. male hormones prevent expression of the calico phenotype.
c. two X chromosomes are needed for the expression of the calico phenotype.
d. two Y chromosomes are needed for the expression of the calico phenotype.
e. one X chromosome and one Y chromosome are needed for the expression of the calico phenotype.
____ 37. Breeding a yellow dog with a brown dog produced puppies with both yellow and brown hairs. This is an example of:
a. variegation.
b. codominance.
c. incomplete dominance.
d. epistasis.
e. a polygenic trait.
____ 38. In genetics, map units express the distance between:
a. chromosomes during metaphase.
b. two loci on a chromosome.
c. alleles.
d. polar bodies.
e. None of the above
____ 39. If a couple is planning on having just two children, what is the probability that both will be male?
a. 0
b. 1/4
c. 1/2
d. 3/4
e. 1
____ 40. Separation of paired alleles takes place during:
a. anaphase of mitosis.
b. cytokinesis of mitosis.
c. anaphase I of meiosis.
d. telophase II of meiosis.
e. cytokinesis of meiosis.
____ 41. The probability that two genes will be separated by crossing over is related to:
a. the phenotype that they control.
b. how far the two genes are from the centromere.
c. the distance between the two genes on the chromosome.
d. whether the two genes are located on a sex chromosome.
e. how far the genes are from the kinetochore.
____ 42. A brown-eyed couple that are heterozygous for eye color are planning on having two children. What is the probability that both children will have blue eyes?
a. 0
b. 1/32
c. 1/16
d. 1/4
e. 1/2
____ 43. What are the possible phenotypes of the children if the mother's genotype is IAiO for blood type and the father is IAIB? (Use the Punnett square to verify your answer.)
a. all AB
b. 1/2 A: 1/2 B
c. 1/2 A: 1/2 AB
d. 1/2 A: 1/4 B: 1/4 AB
e. 1/4 A: 1/4 B: 1/4 AB: 1/4 O
____ 44. A haploid individual has a maximum of ________ different alleles for a particular locus within its genome
a. one d. four
b. two e. number of genes minus one
c. three
____ 45. In the not too distant future you will be working with your own fruitfly cultures. How many pairs of autosomes do fruitflies have?
a. one d. four
b. two e. twenty-two
c. three
Essay
46. 10 pts. During lecture we have been spending a lot of time with Punnett squares. You have learned that we use Punnett squares to predict the genotypes and phenotypes of future generations. Suppose you spent the Labor Day weekend creating and completing a large number of Punnett squares. During that time you were making some very important assumptions. On the answer sheet [front and back if necessary], explain your assumptions regarding meiosis, the principle of segregation, and the principle of independent assortment.
Exam 1
Answer Section
MULTIPLE CHOICE
1. ANS: D
2. ANS: A
3. ANS: B
4. ANS: A
5. ANS: E
6. ANS: E
7. ANS: B
8. ANS: B
9. ANS: C
10. ANS: C
11. ANS: D
12. ANS: E
13. ANS: C
14. ANS: B
15. ANS: A
16. ANS: D
17. ANS: B
18. ANS: C
19. ANS: E
20. ANS: B
21. ANS: E
22. ANS: A
23. ANS: E
24. ANS: B
25. ANS: C
26. ANS: C
27. ANS: D
28. ANS: A
29. ANS: A
30. ANS: D
31. ANS: D
32. ANS: A
33. ANS: D
34. ANS: D
35. ANS: B
36. ANS: C
37. ANS: B
38. ANS: B
39. ANS: B
40. ANS: C
41. ANS: C
42. ANS: C
43. ANS: D
44. ANS: A
45. ANS: C
ESSAY
46. ANS:
You assumed:
1) meiosis is the process that created the gametes you added to the column and row headings,
2) that homologous chromosomes separated during meiosis so that only one homologue exists in each gamete, and
3) that if you were dealing with more than one locus, the different loci assorted independently [not linked].