Gen Bio 115 Exam 2 '21

1. A cell that is in the M phase of the cell cycle is exposed to a toxin that prevents the separation of identical DNA molecules. Hypothesize which of the following will be the most immediate outcome.

a. the nuclear envelope will not break down.
b. the chromosomes will not line up.
c. the microtubules will not depolymerize.
d. the sister chromatids will not move to opposite poles.

d. the sister chromatids will not move to opposite poles.

2. A cell in G1 is diploid and has 34 chromosomes. What is the ploidy of the daughter cells after this cell goes through mitosis?

a. 2n = 17
b. n = 34
c. 2n = 68
d. 2n = 34
d. 2n = 34

d. 2n = 34

3. Correctly sequence the following events in the cell cycle starting with the start of S phase.

I. DNA is replicated
II. Nuclear envelope reforms
III. Chromosomes condense.
IV. Mitotic spindle fiber attach to the kinetochores.
V. Sister chromatids move to opposite sides of the cell

a. I -> III -> IV -> V -> II
b. I -> IV -> III -> II -> V
c. III -> IV -> I -> II -> V
d. III -> I -> V -> IV -> II

a. I -> III -> IV -> V -> II

4. White-tailed deer have 70 chromosomes in each of their kidney cells. During the cell cycle of a deer kidney cell, there are ____ chromosomes in the cell during interphase and ____chromosomes in the cell during the mitotic phase.

a. 35;35
b. 35;70
c. 70;35
d. 70;70

d. 70;70

5. A scientist is studying the cell cycle. She lyses several cells and runs an assay for cell components. Her sample shows high levels of helicase and SSBP (single-stranded binding proteins.) In which stage of the cell cycle are her sample cells currently?

a. Prophase
b. Metaphase
c. Anaphase
d. Interphase

d. Interphase

6. In the following image Y is a ___ and Z is a _____.

a. sister chromatid, centromere
b. chromosome, sister chromatid
c. kinetochore handles, chromosome
d. chromosome, centromere

b. chromosome, sister chromatid

7. Identify chromosome number. In the following image, cell A has _____ chromosomes and cell B has ______ chromosomes.

a. 6, 3
b. 3, 6
c. 12 ,6
d. 6, 6

d. 6, 6

8. Sequence mitosis and meiosis. During which stage[s] of mitosis and meiosis do sister chromatids separate?

I. Anaphase
II. Anaphase I
III. Anaphase II

A. I and III
B. I and II
C. II only
D. I, II, and III

A. I and III

9. Aedes augypti (mosquitos) have 6 chromosomes in their somatic cells. In males, specialized cells undergo meiosis to produce sperm. Those cells that are undergoing meiosis contain ____ chromosomes during prophase I and ___ chromosomes during prophase II.

a. 3; 12
b. 3; 6
c. 6; 6
d. 6; 3

d. 6; 3

10. Identify which of the following is a benefit of asexual reproduction.

a. Genetic variation
b. Need to find a mate
c. Only a single parent
d. Mutations take a toll

c. Only a single parent

11. Identify the stage of meiosis where the cell(s) is/are haploid.

a. S phase of interphase
b. Interkinesis
c. Metaphase I
d. Prophase I

b. Interkinesis

12. Compare and contrast stages of meiosis. Which of the following images depicts a cell in Metaphase II?

a. I
b. II
c. III
d. IV

c. III

13. Sequence the process of meiosis. You have found a plant cell that has a ploidy of 20n and 2000 chromosomes. A cell from this plant in metaphase II has a ploidy of _____ and the number of chromosomes is ______.

a. 10n , 1000
b. 20n , 2000
c. 10n, 500
d. 20n, 1000

a. 10n , 1000

14. Compare and contrast life cycles. Which of the following occur in the lifecycle of BOTH a fungus and an animal?

I. fertilization
II. mitosis
III. meiosis
IV. 2n cells
V. haploid cells

a. I, III, and IV
b. I, II, and V
c. III, IV and IV
d. I, II, III, IV and V

d. I, II, III, IV and V

15. Sequence meiosis. During which phase of meiosis is ploidy reduced?

a. S phase of interphase
b. Second meiotic division
c. Interkinesis
d. First meiotic division

d. First meiotic division

16. Identify which of the following terms describes an individual who has 2 different alleles for a gene.

a. Homozygous recessive
b. Homozygous dominant
c. Heterozygous
d. Hemizygous

c. Heterozygous

17. Which of the following observations made by Mendel invalidated the hypothesis of blending inheritance?

I. F1 and F2 individuals were identical to parental generation
II. F1 was comprised entirely of a single parental phenotype
III. F2 contained parental phenotypes that were absent in F1
IV. One parental phenotype was permanently lost

a. II and IV
b. I and IV
c. I and II
d. II and III

d. II and III

18. Golden retreiver dogs can carry a recessive trait for deafness (h). A dog breeder wants to test if their dogs are carying deafness, so they conduct a test cross with a dog that is a carrier for deafness?

a. Hh x hh
b. hh x hh
c. HH x hh
d. Hh x Hh

a. Hh x hh

19. Based on this Punnett square, which of the following statements are TRUE?

I. This is a monohybrid cross
II. This is a test cross
III. Both parents are heterozygous
IV. The parent are homozygous individuals
V. All of the offspring express the dominant trait

a. I and III
b. II and IV
c. I, II, and III
d. II, IV and V

a. I and III

20. Identify which of the following is true of dominant and recessive alleles?

a. Dominant and recessive alleles are never found in the same individual.
b. Dominant alleles will mask the presence of recessive alleles.
c. Only dominant alleles can determine phenotype.
d. When both are present, the resulting phenotype is a combination of the two.

b. Dominant alleles will mask the presence of recessive alleles.

21. Which of the following statements are TRUE regarding alleles? They are:

I. sequences of DNA
II. segregated into different gametes
III. only found in diploid organisms
IV. versions of a gene

a. I and IV
b. I, II, and III
c. III and IV
d. I, II, and IV

d. I, II, and IV

22. Apply probability rules. Identify in which of the following situations is it appropriate to use the addition rule.

I. Determining the combined probability of mutually exclusive events
II. Determining the combined probability of independent events
III. Determining the combined probability of events that cannot occur simultaneously

a. I only
b. II only
c. III only
d. I and III

d. I and III

23. The combined probability of two independent events is:

a. also described as the probability of independent events
b. determined by multiplying their separate probabilities
c. the probability of two events that are mutually exclusive
d. described as "the probability of one event OE the probability of the other event"

b. determined by multiplying their separate probabilities

24. Identify which of the following is not a reason that fruit flies made a good test organism.

a. many distinct characteristics
b. short generation time
c. many chromosomes
d. easy to control breeding

c. many chromosomes

25. A female carrying a recessive X-linked trait mates with a male who does not have the trait. Calculate the probability that the first offspring is a male who does not have the trait.

a. 1
b. 0.75
c. 0.5
d. 0.25

d. 0.25

26. Barr bodies:

a. occur in autosomal chromosomes in females
b. occur when one X is randomly deactivated
c. involve the Y chromosome
d. can only occur in females

b. occur when one X is randomly deactivated

27. An animal with the sex chromosomes XY is hemizygous for certain characters. What does this mean?

a. Every allele in the nucleus is expressed
b. On the X chromosome, recessive alleles mask dominant alleles
c. Every allele on the X chromosome is expressed
d. All of the recessive alleles on the somatic chromosomes are expressed

c. Every allele on the X chromosome is expressed

28. You are studying gene expression in humans. The trait that you are interested in has the following pattern: Neither parent expresses the trait. One quarter of the daughters and one quarter of the sons express the trait.

Hypothesize what type of inheritance this pattern COULD be:

I. Mendelian
II. Sex-linked on the X chromosome
III. Sex-linked on the Y chromosome.

a. I only
b. II only
c. III only
d. I or II

a. I only

29. Diagnose sex linkage. A man inherits a X-linked disorder. Hypothesize which of the following ancestors could be the source of his disorder.

I. paternal grandmother (his father's mother)
II. maternal grandmother (his mother's mother)
III. paternal grandfather (his father's father)
IV. maternal grandfather (his mother's father)

a. III or IV
b. I or III
c. II or IV
d. I or II

c. II or IV

30. Male cockatiels have the sex chromosome pair ZZ while the female cockatiels have the sex chromosome pair ZW. Identify which of the following statements are TRUE.

I. Z-linked diseases are more commonly expressed in female cockatiels
II. One Z chromosome in male cockatiels is condensed into a Barr body
III. male cockatiels can be heterozygous for sex-linked traits
IV. female cockatiels are heterogametic

a. I and II
b. I, II, and III
c. I and III
d. I, II, III, and IV

d. I, II, III, and IV

31. Identify which of the following is central finding of Thomas Morgan that was different from what Mendel concluded?

a. Alleles segregate during gamete formation
b. Homozygous recessive individuals exhibit recessive phenotypes
c. Dominant alleles mask recessive alleles
d. Genes move on chromosomes, not as individual units

d. Genes move on chromosomes, not as individual units

32. A sequence of one DNA strand is:

3' A A T G G C T A C 5'
Identify the correct sequence of the complementary DNA strand.

a. 5' T T A C C G A T G 3'
b. 5' A A T G G C T A C 3'
c. 5' U U A C C G A U G 3'
d. 3' C A T C G G T A A 5'

a. 5' T T A C C G A T G 3'

33. Identify which of the following are components of a cytosine nucleotide.

I. a purine
II. a pyrimidine
III. a five-carbon sugar
IV. a phosphate group

a. I and III
b. II and III
c. I, III, and IV
d. II, III, and IV

d. II, III, and IV

34. Correctly sequence the following proteins in the order in which they participate in DNA replication, starting with the breaking of hydrogen bonds.

I. DNA polymerase
II. Primase
III. Helicase
IV. Single-strand binding proteins

a. I -> III -> II -> IV
b. II -> I -> IV -> III
c. III -> I -> II -> IV
d. III -> IV -> II -> I

d. III -> IV -> II -> I

35. Referring to the following image, which of the following statement(s) is/are TRUE?

I. 5' end of the molecule
II. 5' end of the molecule
III. Elongation only occurs here

a. I and III
b. II only
c. I only
d. III only

c. I only

36. This structure represents a nucleotide. Based on this information, which statements are TRUE?

I. This will pair with a pyrimidine
II. It is either adenine or guanine
III. The hydroxyl group is attached to the 5' carbon
IV. It is found in prokaryotes and eukaryotes
V. It is found in chromosomes, but not in chromatids

a. I, II and IV
b. III, IV and V
c. I, III, and IV
d. II, IV and V

a. I, II and IV

37. Hypothesize where a reaction which breaks hydrogen bonds would affect a DNA molecule. Between a pyrimidine and:

a. the 3' hydroxyl group
b. a phosphate group
c. the 5' carbon of deoxyribose
d. a purine

d. a purine

38. Hypothesize the result of a mutation that prevented RNA primase from functioning. How would DNA replication be affected?

a. Replication would not be bidirectional from the origin of replication
b. Okazaki fragments on the lagging strand would not be joined
c. DNA replication would be unaffected
d. DNA polymerase would be unable to place the first DNA nucleotide

d. DNA polymerase would be unable to place the first DNA nucleotide

39. Identify which of the following correctly describes the operation of DNA polymerase.

I. Adds new nucleotides to the 5' side of the new DNA strand
II. Catalyzes the formation of phosphodiester bonds
III. Synthesizes a complementary daughter to the parent strand

a. I only
b. II only
c. III only
d. II and III

d. II and III

40. Identify which of the following statements best describes transcription

a. mRNA used to generate specific polypeptide
b. DNA used as template to generate specific mRNA
c. mRNA converted into polypeptide
d. Polypeptide used to generate specific mRNA

b. DNA used as template to generate specific mRNA

41. Identify which of the following occurs ONLY in eukaryotes.

a. translation
b. formation of peptides bonds
c. placement of a 5' cap on pre-mRNA
d. mRNA binding to ribosome

c. placement of a 5' cap on pre-mRNA

42. Correctly sequence the following events in eukaryotic gene expression

I. RNA polymerase attaches to promotor
II. mRNA molecule receives poly A tail
III. mRNA leaves the nucleus
IV. Start codon triggers translation initiation
V. Transcript is elongated

a. I -> II -> III -> IV -> V
b. I -> V -> II -> III -> IV
c. II -> III -> IV -> I -> V
d. IV -> II -> V -> III -> I

b. I -> V -> II -> III -> IV

43. Identify the function of aminoacyl-tRNA synthetase.

a. Catalyze peptide bond formation between amino acids
b. Terminate translation
c. Covalently link an amino acid to a tRNA
d. Translocate the ribosome by binding to a tRNA

c. Covalently link an amino acid to a tRNA

44. Compare and contrast DNA and RNA. Which statement(s) describe(s) BOTH DNA and RNA?

I. It is a polymer of nucleotides
II. It has a sugar linked to a phosphate group
III. It can be found in the nucleus
IV. It is normally double stranded in cells

a. I only
b. II and III
c. I, II, and III
d. I, II, III and IV

c. I, II, and III

45. Compare and contrast DNA replication, transcription and translation. Which of the following processes are dependent on complementary base pairing?

I. Transcription
II. Translation
III. DNA replication

a. I and III
b. III only
c. I, II and III
d. I and II

c. I, II and III

46. Correctly sequence translation.

I. Large ribosomal submit joins the initiation complex
II. Small ribosomal subunit binds with mRNA
III. Peptide bond formation
IV. Release factors bind to codon in A site
V. Initiator tRNA base-pairs with start codon

a. II -> V -> I -> III -> IV
b. V -> I -> II -> III -> IV
c. II -> I -> III -> V -> IV
d. V -> II -> I -> IV -> III

a. II -> V -> I -> III -> IV

47. Cycloheximide is a chemical that interferes with translocation and thereby inhibits protein synthesis in eukaryotes. Hypothesize the effects when a cell is treated with cycloheximide.

I. Translation elongation will not occur normally
II. The translation initiation complex will not form
III. No mRNA will be produced
IV. RNA polymerase will not function normally
V. Peptide bond formation by will be inhibited

a. I and II
b. I and V
c. II, III, and IV
d. II, IV and V

b. I and V

48. On a prokaryotic operon, where does the repressor protein bind?

a. Inducer
b. Start codon
c. Promoter
d. Operator

d. Operator

49. Hypothesize the effect on operon expression if a mutation prevents the inducer from binding to the repressor.

a. Operon would never be expressed
b. Only low levels of expression possible
c. Operon always expressed at low levels
d. Operon always expressed at high levels

a. Operon would never be expressed

50. A rise in active catabolite activator protein (CAP) in an E. Coli cell indicates that:

a. very little glucose is available and cAMP levels are rising
b. the cell has equal amounts of glucose and lactose available for metabolism
c. the lac operon promoter's affinity for RNA polymerase will decrease
d. allolactose will bind efficiently to the operator

a. very little glucose is available and cAMP levels are rising

51. Hypothesize which of the following would be TRUE for an E. Coli cell living in a medium of high glucose and high lactose?

I. High levels of activated CAP (Catabolite Activator Protein)
II. Low cAMP levels
III. High levels of LAC transcription
IV. Operator on LAC operon is blocked by a repressor
V. Low level of LAC transcription

a. I and III
b. IV only
c. II and III
d. II and V

d. II and V

52. Which of the following is an example of positive regulation of an operon?

a. levels of translation are adjusted based on cellular changes
b. several genes are transcribed simultaneously
c. CAP helps RNA polymerase attach to the promoter
d. the operator of an operon is blocked by a repressor

c. CAP helps RNA polymerase attach to the promoter

53. Compare and contrast prokaryotic and eukaryotic DNA and gene regulation. Which of the following processes occur in BOTH?

I. Translation
II. Replication
III. Regulation by operons
IV. Histone modification
V. Transcription

a. I and III
b. III and IV
c. I, II and IV
d. I, II and V

d. I, II and V

54. Sequence gene regulation in eukaryotes

I. Adding a 5' cap to pre-mRNA
II. DNA packaging
III. Regulation of translation
IV. Protein processing and folding

a. II -> I -> III -> IV
b. I -> II -> III -> IV
c. I -> III -> IV -> II
d. II -> III -> I -> IV

a. II -> I -> III -> IV

55. A mutation occurs in your pet rabbit that prevents DNA methylation in a specific gene. Hypothesize the effect of this mutation on that gene.

a. more frequent transcription
b. translation cannot occur
c. this mutation does not have any effects
d. transcription is inhibited

a. more frequent transcription

56. Which of the following are REQUIRED for DNA replication, transcription, PCR and dideoxy chain termination sequencing?

I. Complementary base pairing
II. DNA primers
III. DNA polymerase
IV. RNA nucleotides

a. III only
b. I only
c. I and IV
d. II and III

b. I only

57. Dr. Patel is running a thermocycler in her lab to PCR a small sample of DNA. She places the sample in the machine and leaves for the night. Later that night, the machine breaks, and the temperature remains at a high 75 degree C for the entire process. What is the result of this malfunction.

a. Excess DNA is sequenced
b. DNA strands do not separate
c. Taq polymerase cannot extend from primer
d. RNA polymerase does not bind to the promoter

b. DNA strands do not separate

58. During the annealing step in PCR, the:

a. primer binds to the target
b. backbone of the DNA denatures
c. hydrogen bonds between bases break.
d. DNA molecules are synthesized

b. backbone of the DNA denatures

59. Correctly sequence the steps of DNA dideoxy sequencing.

I. DNA fragment is denatured into single strands
II. Load single strands onto gel
III. Detector senses fluorescent tag
IV. Begin incubation with primer, polymerase, dNTPs, and ddNTPs
V. Strand elongation

a. I -> IV -> V -> II -> III
b. I -> V -> II -> IV -> III
c. I -> II -> IV -> III -> V
d. I -> IV -> II -> V -> III

a. I -> IV -> V -> II -> III

60. Identify which of the following nucleotides would allow the elongation of a new strand of DNA?
(picture here)

a. I and II
b. II and III
c. I only
d. III only

b. II and III

61. Identify which of the following is TRUE regarding gel electrophoresis.

a. Large DNA molecules migrate faster than small DNA molecules.
b. It involves several cycles of DNA synthesis.
c. Heat is used to move DNA molecules.
d. DNA migration is due to its negative charge.

d. DNA migration is due to its negative charge.

62. Compare and contrast DNA replication and PCR. Which of the following occurs in DNA replication in a eukaryotic cel, but NOT during PCR?

a. Synthesis of DNA in the 3' to 5' direction
b. Unwinding of the DNA helix by helicase
c. Binding of a DNA primer to the template
d. Hydrogen bonding between complementary nucleotides

b. Unwinding of the DNA helix by helicase

63. Compare and contrast DNA replication, transcription and PCR. Which of the following are TRUE?

I. All involve a leading and lagging strand
II. All involve DNA polymerase
III. All require a template strand
IV. Only DNA replication requires RNA primers

a. I and IV
b. I and II
c. III and IV
d. II and III

c. III and IV

64. For an individual to express an autosomal recessive trait, what must be true?

a. They must receive a recessive allele from just one parent
b. They must have two recessive alleles
c. They must have a parent who expresses the recessive trait
d. Both parents must express the recessive trait

b. They must have two recessive alleles

65. For an individual to express an X-linked recessive trait, what must be true?

a. They must have two X chromosomes
b. They must have at least one dominant allele
c. XY individuals can express the trait with just one recessive allele
d. At least one parent must express the recessive trait

c. XY individuals can express the trait with just one recessive allele

66. Identify the types of human genetic disorders that can be caused by nondisjunction.

I. Monosomy
II. Aneuploidy
III. Autosomal recessive
IV. X-linked recessive

a. II and III
b. I, III, and IV
c. II and IV
d. I and II

d. I and II

67. Use the following pedigree to answer the following question.

This chart represents the expression of an autosomal recessive disease. Affected individuals are represented by filled in shapes. Males are represented as squares and females are represented by circles.


If individual II-2 is cross-bred with individual IV-4. What present of their children will be carriers for the disease?

a. 25%
b. 50%
c. 75%
d. 100%

b. 50%

68. Cystic fibrosis is an autosomal recessive genetic disease where a person must inherit two recessive alleles to express the disease. Which of the following represent possible parents of a child with cystic fibrosis?

a. X^F X^f (&) X^F y
b. Ff (&) FF
c. X^f X^f (&) X^f y
d. Ff (&) Ff

d. Ff (&) Ff

69. Identify which of the following indicates a trisomy in humans.

a. a gamete with 22 autosomes + Y
b. a somatic cell with 44 autosomes + XX
c. a somatic cell with 46 chromosomes + Y
d. a 3n somatic cell

c. a somatic cell with 46 chromosomes + Y

70. Which of the following is a mechanism that could preserve harmful recessive traits in a population?

a. Natural selection
b. Heterozygote advantage
c. Dominant lethality
d. Aneuploidy

b. Heterozygote advantage