Biology- Exam IV

30. A normal XY male has a son with the karyotype XYY. The likely explanation is: A) dosage compensation. B) translocation. C) second-division nondisjunction. D) first-division nondisjunction. E) copy-number variation.

C) second-division nondisjunction.

46. All of these events happen during M phase except: A) formation of the spindle. B) condensation of the chromosomes. C) synthesis of DNA. D) separation of sister chromatids.

C) synthesis of DNA.

23. The incidence of Down syndrome is positively correlated with: A) copy-number variation. B) the father's age. C) the mother's age. D) inversion. E) None of the other answer options is correct.

C) the mother's age.

73.Which of the options is circled in this electron micrograph? A) one double-stranded DNA molecule B) one single strand of a DNA molecule C) two double-stranded DNA molecules

C) two double-stranded DNA molecules

79. The epithelial cells in the skin of an animal have 24 chromosomes. How many chromosomes are present in the gametes of this animal? A) 12 B) 24 C) 48 D) 96

A) 12

80. Consider a diploid organism with a haploid complement of 4 chromosomes in its gametes. At meiotic prophase I, how many total chromosomes copies will be present in a cell? A) 16; 4 pairs of homologous chromosomes and 2 sister chromatids per chromosome B) 8; 4 pairs of homologous chromosomes C) 12; 4 pairs of homologous chromosomes and their haploid complement D) 4; 1 complete set of chromosomes

A) 16; 4 pairs of homologous chromosomes and 2 sister chromatids per chromosome

28. Diploid somatic cells of elephants have 56 chromosomes. If nondisjunction of one of an elephant's chromosomes occurs in meiosis I, the resulting sperm are expected to have the chromosome complement: A) 29, 29, 27, 27. B) 28, 28, 29, 27. C) 28, 28, 28, 28. D) 29, 29, 28, 28. E) 56, 56, 57, 55.

A) 29, 29, 27, 27.

31. How many chromosomes are there in a human cell that is tetraploid? A) 92 B) 46 C) 69 D) 23

A) 92

38. The M cyclin-CDK complex: A) All of these choices are correct. B) initiates many events of mitosis. C) triggers phosphorylation of certain nuclear proteins, resulting in breakdown of the nuclear envelope during prophase. D) phosphorylates proteins that promote formation of the mitotic spindle. E) controls passage of the G1 checkpoint.

A) All of these choices are correct.

Studies of rapidly dividing embryonic animal cells revealed: A) All of these choices are correct. B) a periodic activation of protein kinases in sync with the cell cycle. C) that increased levels of cyclin proteins are correlated with activation of cyclin-dependent kinase (CDK) enzymes. D) that inhibition of protein synthesis blocks mitosis. E) increased synthesis of certain proteins in sync with the cell cycle.

A) All of these choices are correct.

88. Which of the statements concerning cyclin-dependent kinases (CDKs) is true? A) All of these choices are true. B) CDKs are enzymes that attach phosphate groups to other proteins. C) CDKs are active, or "turned on," when complexed with cyclins. D) CDKs are present throughout the cell cycle. E) CDKs are inactive, or "turned off," in the presence of cyclins.

A) All of these choices are true.

72. The correct sequence of steps in the eukaryotic cell cycle is: A) G1 → S phase → G2 → mitosis → cytokinesis. B) G0 → S phase → G1 → S phase → G2 → mitosis → cytokinesis. C) G0 → S phase → G1 → G2 → cytokinesis → mitosis. D) G0 → S phase → G1 → S phase → G2 → cytokinesis → mitosis. E) G1 → S phase → G2 → cytokinesis → mitosis.

A) G1 → S phase → G2 → mitosis → cytokinesis.

21. The most common form of hemophilia is a defect in blood clotting factor VIII, which is caused by a mutant form of a gene on the X chromosome. Boys who inherit that mutation from their mother suffer from uncontrolled bleeding. Girls carrying one copy of this mutation have near normal blood clotting. Uncommonly, a girl is born with hemophilia even though both parents have normal phenotypes. Which of the statements might explain hemophilia in a girl born to parents with normal blood clotting phenotypes? A) Nondisjunction during sperm formation resulted in her receiving no sex chromosome from her father and an X chromosome from her mother; she is XO. B) Nondisjunction during egg formation resulted in her receiving no X chromosome from her mother but an X from her father; she is XO. C) A nondisjunction event in sperm production resulted in her receiving X and Y chromosomes from her father and an X from her mother; she is XXY. D) Nondisjunction during egg formation resulted in her receiving two X chromosomes from her mother and an X chromosome from her father; she is XXX.

A) Nondisjunction during sperm formation resulted in her receiving no sex chromosome from her father and an X chromosome from her mother; she is XO.

47. Paramecium is a single-cell eukaryotic organism that can reproduce by mitotic cell division. Prior to the M phase of the cell cycle, which of the events must occur? A) The cell must replicate its chromosomes. B) The cell must first be fertilized. C) The nucleus must divide. D) Sister chromatids must be separated. E) The nuclear envelope must disintegrate.

A) The cell must replicate its chromosomes.

76. Taxol is an anti-cancer drug that prevents uncontrolled cell proliferation by blocking the lengthening and shortening of microtubules, which causes arrest of the cell cycle. If dividing cells are treated with Taxol, what will occur? A) The cells will be unable to form a mitotic spindle. B) The cells will be unable to replicate their chromosomes. C) The cells will be unable to divide the cytoplasm in cytokinesis. D) The cells will be unable to increase cyclin levels required to pass the G1 checkpoint.

A) The cells will be unable to form a mitotic spindle.

96. In a normal cell, tumor suppressors are responsible for: A) allowing the cell to correct replication errors. B) increasing the rate of cell division. C) signaling that cells should pass a cell cycle checkpoint. D) signaling that DNA replication should begin.

A) allowing the cell to correct replication errors.

Which of the cells most likely came from a culture treated with emetine or aphidicolin? A) cell A B) cell B C) cell C

A) cell A

Which of these compounds would be most likely to arrest cells in prophase? A) colchicine: an inhibitor of microtubule formation B) cytochalasin: an inhibitor of actin microfilament assembly C) aphidicolin: an inhibitor of DNA polymerase activity D) emetine: an inhibitor of ribosome activity (and therefore protein synthesis)

A) colchicine: an inhibitor of microtubule formation

55. At the end of mitosis, the daughter cells are _____, whereas at the end of meiosis the daughter cells are _____. A) diploid; haploid B) haploid; diploid C) diploid; polyploid D) polyploid; haploid

A) diploid; haploid

Which of these compounds would most likely to prevent cells from passing the G1 checkpoint? A) emetine: an inhibitor of ribosome activity (and therefore protein synthesis) B) colchicine: an inhibitor of microtubule formation C) aphidicolin: an inhibitor of DNA polymerase activity D) cytochalasin: an inhibitor of actin microfilament assembly

A) emetine: an inhibitor of ribosome activity (and therefore protein synthesis)

In which of the intervals would the addition of an inhibitor of DNA polymerase affect the progression of the cells through the cell cycle? A) interval 1 B) interval 2 C) interval 3 D) interval 4 E) interval 5

A) interval 1

In which of the intervals do the cells have twice as many chromosomes as the cells in interval 5? A) intervals 1, 2, and 3 B) interval 2 C) intervals 1 and 2 D) intervals 2 and 3 E) interval 1

A) intervals 1, 2, and 3

In which of the intervals is the amount of DNA reduced by one-half? A) intervals 3 and 4 B) interval 3 C) interval 4 D) interval 1 E) intervals 1 and 5

A) intervals 3 and 4

20. Nondisjunction in _____ results in offspring inheriting a change in the number of chromosomes. A) meiosis B) mitosis

A) meiosis

95. During meiosis, genetic variability is introduced during which phase? A) metaphase I B) anaphase II C) prophase II D) telophase I

A) metaphase I

52. The correct sequence of steps in the M phase of the cell cycle is: A) prophase, prometaphase, metaphase, anaphase, telophase, cytokinesis. B) prophase, prometaphase, metaphase, anaphase, telophase, nuclear division. C) prophase, metaphase, prometaphase, anaphase, nuclear division, telophase. D) prophase, metaphase, anaphase, telophase, cytokinesis, nuclear division.

A) prophase, prometaphase, metaphase, anaphase, telophase, cytokinesis.

63. Which of the choices would be most likely to lead to the development of cancer? A) the activation of an oncogene and the inactivation of a tumor suppressor gene B) the activation of a proto-oncogene C) the activation of a tumor suppressor gene D) the activation of an oncogene and the activation of a tumor suppressor gene

A) the activation of an oncogene and the inactivation of a tumor suppressor gene

83. A homologous chromosome pair is best described as 2 chromosomes that have: A) the same genes in the same order but possibly with different alleles of some of the genes. B) the same alleles of the same genes in the same order. C) different genes arranged in a different order with potentially different alleles of some of the genes. D) different alleles of the same genes arranged in a different order. E) identical sequences of nucleotides.

A) the same genes in the same order but possibly with different alleles of some of the genes.

36. Which of these events includes a checkpoint in the cell cycle? A) the transition from G1 to S phase B) the transition from anaphase to telophase C) the transition from S phase and the completion of DNA synthesis to G2 phase D) All of these events include a checkpoint in the cell cycle.

A) the transition from G1 to S phase

117. There are three phases of interphase called: G1 phase, S phase and G2 phase. A) true B) false

A) true

118. Cells that have fully differentiated and no longer divide are said to be in G0 phase. A) true B) false

A) true

42. The genetic information of daughter cells is the same as the genetic information of the parent in binary fission. A) true B) false

A) true

43. A mutation acquired by a bacterium will very likely be inherited by both daughter cells. A) true B) false

A) true

98. There are two stages to the cell cycle: M phase and interphase. A) true B) false

A) true

61. P53 is an example of a(n): A) tumor suppressor. B) proto-oncogene. C) oncogene. D) cyclin-dependent kinase.

A) tumor suppressor.

91. The first oncogene to be discovered: A) was discovered in a Rous sarcoma virus that causes cancer. B) is a gene that contributes to uncontrolled cell division or cancer. C) is a protein kinase that acts to promote cell division. D) has a less-active normal counterpart called a proto-oncogene. E) All of these choices are correct.

A) was discovered in a Rous sarcoma virus that causes cancer.

71. Prokaryotic cells and eukaryotic cells reproduce by cell division. Regardless of the type of cell, all cells must _____ before they divide. A) complete mitosis B) separate sister chromatids from one another C) make a copy of their genetic information D) reconstruct their nuclear envelope

C) make a copy of their genetic information

74. How many copies of each gene are present in human skin cells at G1 of interphase? A) 4 B) 2 C) 8 D) 1

B) 2

29. Diploid somatic cells of elephants have 56 chromosomes. If nondisjunction of one of an elephant's chromosomes occurs in meiosis II, the resulting sperm are expected to have the chromosome complement: A) 28, 28, 28, 28. B) 28, 28, 29, 27. C) 29, 29, 27, 27. D) 29, 29, 28, 28. E) 56, 56, 57, 55.

B) 28, 28, 29, 27.

81. The FoxP2 gene is thought to be involved in language in humans. At prophase I, how many copies of the FoxP2 gene are present in a cell? Keep in mind that humans are diploid. A) 2 copies; 1 on each homologous chromosome B) 4 copies; 1 on each sister chromatid in a pair of homologous chromosomes C) 8 copies; 1 on each sister chromatid in a pair of homologous chromosomes D) 8 copies; 1 on each strand of each chromatid per homologous pair

B) 4 copies; 1 on each sister chromatid in a pair of homologous chromosomes

51. Actin microfilaments and tubulin-based microtubules are important components of the cytoskeleton that function during mitosis. Which process of cell division would be most affected if actin function was blocked? A) The mitotic spindle would not form. B) Cytokinesis would not occur to divide the cytoplasm. C) The sister chromatids would not separate. D) The chromosomes would not replicate.

B) Cytokinesis would not occur to divide the cytoplasm.

87. CDKs are important in the regulation of the cell cycle. They carry out their function by: A) removing phosphate groups from target proteins. B) adding phosphate groups to target proteins. C) degrading cyclin proteins. D) preventing the progression of a cell from one stage of the cell cycle to the next.

B) adding phosphate groups to target proteins.

Which of these compounds would be most likely to arrest cells in S Phase? A) cytochalasin: an inhibitor of actin microfilament assembly B) aphidicolin: an inhibitor of DNA polymerase activity C) colchicine: an inhibitor of microtubule formation D) emetine: an inhibitor of ribosome activity (and therefore protein synthesis)

B) aphidicolin: an inhibitor of DNA polymerase activity

44. Mitosis most likely evolved from what process? A) the cell cycle B) binary fission C) cytokinesis D) meiosis

B) binary fission

Which of the cells came from a culture treated with colchicine? A) cell A B) cell C C) cell B

B) cell C

56. Which of the events could produce new combinations of alleles of genes along a chromosome if crossing over happened during prophase I of meiosis? A) crossing over between sister chromatids B) crossing over between non-sister chromatids of homologous chromosomes C) either kind of crossing over could produce new combinations of alleles

B) crossing over between non-sister chromatids of homologous chromosomes

34. The amount of _____ is fairly constant throughout the cell cycle, but the amount of _____ varies. A) DNA; cyclins B) cyclin-dependent kinases; cyclins C) cyclin-dependent kinase; DNA D) cyclins; DNA

B) cyclin-dependent kinases; cyclins

115. The M phase consists of two events: prophase and cytokinesis. A) true B) false

B) false

116. Interphase is typically the shortest of the two stages of the cell cycle. A) true B) false

B) false

22. Autosomal trisomies are associated with the X or Y chromosome. A) true B) false

B) false

58. During meiosis, two rounds of DNA synthesis are required to form four gametes from one parent cell. A) true B) false

B) false

In which of the intervals are most of the cells in meiosis II? A) interval 2 B) interval 4 C) interval 3 D) interval 1 E) interval 5

B) interval 4

62. An enzyme that catalyzes the addition of a phosphate group from ATP to another molecule is called a: A) phosphorylase. B) kinase. C) phosphatase D) cyclase.

B) kinase.

90. Some genes have important functions in cells, but they can sometimes acquire mutations that cause negative effects, including the development of cancer. These genes are called: A) oncogenes. B) proto-oncogenes. C) tumor suppressor genes. D) viral genes.

B) proto-oncogenes.

54. Colchicine is a drug that blocks the assembly of microtubules. If dividing cells are treated with colchicine, at what stage of mitosis would you predict the arrest would occur? A) late anaphase B) metaphase C) prophase D) telophase E) G1 of interphase

C) prophase

50. Which of the choices is reproduced by binary fission? A) chloroplasts B) archaea C) All of these choices are correct. D) mitochondria E) bacteria

C) All of these choices are correct.

59. If a cell underwent mitosis, and its daughter cells were immediately exposed to chemicals that damaged the DNA, at which stage of the cell cycle checkpoint would you predict the cell would arrest? A) M checkpoint B) G2 checkpoint C) G1 checkpoint D) G1, G2, or the M checkpoints

C) G1 checkpoint

86. Which major checkpoint delays the cell cycle when DNA replication is incomplete? A) M checkpoint B) G1 checkpoint C) G2 checkpoint D) G1, G2, and the M checkpoints

C) G2 checkpoint

41. Which of the statements is true when a cell has a mutation in the p53 gene, such that the p53 protein is not able to be phosphorylated? A) The amount of p53 protein in the nucleus would increase in response to DNA damage. B) The cell would arrest, giving time for the DNA damage to be repaired. C) The cell would proceed through the cell cycle even in the presence of DNA damage. D) Nothing would change in the cell cycle, because the p53 protein is normally not able to be phosphorylated.

C) The cell would proceed through the cell cycle even in the presence of DNA damage.

Which of the cells came from a culture treated with cytochalasin? A) cell C B) cell A C) cell B

C) cell B

26. The lethality of most monosomies and trisomies in humans shows the: A) advantage of sexual reproduction. B) deleterious effects of a variable number of tandem repeat sequences. C) importance of gene dosage (the number of copies of a gene). D) rarity of variation in the number of copies of each gene in the genome.

C) importance of gene dosage (the number of copies of a gene).

84. The rise in cyclin levels correlate with passage of cell cycle checkpoints. Which event is triggered by high cyclin levels? A) polymerization of DNA B) signal transduction from receptors C) kinase activity to phosphorylate specific proteins D) ATP synthesis

C) kinase activity to phosphorylate specific proteins

75. How many copies of each gene are present in human skin cells at G2 of interphase? A) 8 B) 2 C) 6 D) 4

D) 4

78. The random alignment of maternal and paternal homologous chromosomes during metaphase I is one of the ways genetic variability among gametes comes about. For example, it is possible for an organism with 4 pairs of homologous chromosomes to produce gametes with up to 16 different combinations of maternal and paternal chromosomes (24= 16). In the case of humans with 23 pairs of chromosomes, there are over 8 million possible combinations. How many possible combinations of maternal and paternal chromosomes are possible in the gametes of an organism with 6 chromosomes? A) 512 B) 128 C) 256 D) 64 E) 1024

D) 64

89. Processes that regulate cell division in mammals include: A) rapid degradation of cyclins after CDK activation. B) activated cyclin-CDK complexes triggering cell cycle events. C) different cyclins and CDKs acting at different stages of the cell cycle to promote cell division. D) All of these choices are correct. E) production of cyclin proteins that activate CDK enzymes.

D) All of these choices are correct.

48. Which of the statements is correct about cells in G1 phase in the cell cycle? A) Cells in G1 phase attach copies of their chromosomes to the cell membrane in preparation for binary fission. B) Cells at the end of G1 activate the proteins that make the mitotic spindle. C) Cells in G1 phase have a gap in protein synthesis and suppress the process of translation. D) Cells in G1 phase that do not activate the enzymes associated with DNA synthesis for long periods are said to be in G0 phase.

D) Cells in G1 phase that do not activate the enzymes associated with DNA synthesis for long periods are said to be in G0 phase.

60. Which one of the choices would most likely contribute to uncontrolled cell proliferation (that is, cancer)? A) a mutant DNA synthesis mechanism causing blocked chromosome replication B) a mutant cyclin that cannot bind to its normal CDK binding partner C) a mutant enzyme needed for microtubule synthesis/polymerization D) a mutant CDK that was active in the absence of its cyclin binding partner E) a mutant kinetochore protein that causes reduced microtubule attachment

D) a mutant CDK that was active in the absence of its cyclin binding partner

Which of these compounds would be most likely to arrest cells in telophase/cytokinesis? A) emetine: an inhibitor of ribosome activity (and therefore protein synthesis). B) colchicine: an inhibitor of microtubule formation C) aphidicolin: an inhibitor of DNA polymerase activity D) cytochalasin: an inhibitor of actin microfilament assembly

D) cytochalasin: an inhibitor of actin microfilament assembly

39. Cancer-causing genes found in some viruses are called: A) coat protein genes. B) proto-oncogenes. C) tumor suppressor genes. D) oncogenes.

D) oncogenes.

53. Sister chromatids are best described as two DNA molecules that have: A) different genes in a different order with different alleles. B) the same genes in the same order with different alleles. C) different genes in the same order with different alleles. D) the same genes in the same order with the same alleles.

D) the same genes in the same order with the same alleles.

40. Phosphorylated p53 is a protein that accumulates in the nuclei of cells that have damaged DNA where it functions to block the cell cycle and activate DNA repair. The p53 gene that encodes this protein is an example of a(n): A) protein kinase. B) proto-oncogene. C) oncogene. D) tumor suppressor gene.

D) tumor suppressor gene.

77.In a diploid individual, there are two genes called "A" and "B" on one chromosome. One homolog of that chromosome carries A and B alleles of those genes, and the homologous chromosome carries different forms (alleles) of these same genes, a and b. If there is a single crossover between these two genes involving one pair of non-sister chromatids during metaphase I of meiosis, the resulting four gametes would be: A) Ab, Ab, aB, aB. B) AB, ab, AB, ab. C) AaBb, AaBb, AaBb, AaBb. D) AB, AB, ab, ab. E) AB, Ab, aB, ab.

E) AB, Ab, aB, ab.

37. The S cyclin-CDK complex: A) controls the cell cycle during the S and G2 phases. B) triggers initiation of DNA synthesis during the S phase. C) prevents initiation of DNA synthesis a second time during the S and G2 phases. D) both controls the cell cycle during the S and G2 phases and triggers initiation of DNA synthesis during the S phase. E) All of these choices are correct.

E) All of these choices are correct.

33. Which of the processes is most important for passage through the G1 cell cycle checkpoint? A) inhibition of cyclin proteins B) changes in membrane polarization C) expression of genes encoding cyclin-dependent kinases D) activation of DNA polymerase E) activation of cyclin-dependent kinases

E) activation of cyclin-dependent kinases

85. Which one of the choices is capable of phosphorylating key proteins involved in regulating the cell cycle? A) CDK alone B) cyclin alone C) phosphatases D) p53 protein E) cyclin-CDK complex

E) cyclin-CDK complex

27. The presence of an extra X chromosome is more likely to result in a viable human fetus than an extra copy of an autosome because: A) expression of genes from the X chromosome is restricted to early development of females. B) the X chromosome carries few genes, so gene dosage (the number of copies of a gene) is not a problem. C) the X and the Y chromosomes do not recombine along most of their length. D) the X chromosome is the "female" chromosome. E) female mammals inactivate all but one copy of their X chromosomes, which does not occur for autosomes.

E) female mammals inactivate all but one copy of their X chromosomes, which does not occur for autosomes.

92. Considering Douglas Hanahan and Robert Weinberg's Hallmarks of Cancer, which of the choices could block cancer progression? A) uncontrolled cell division in the absence of growth signals B) resistance to signals that slow cell division or promote cell death C) metastasis, which allows invasion of local tissues D) ability to stimulate growth of blood vessels to provide nutrients to the rapidly growing tumor E) inhibitory signals causing cell cycle arrest at the M checkpoint

E) inhibitory signals causing cell cycle arrest at the M checkpoint

In which of the intervals is the number of chromosomes reduced by one-half? A) interval 5 B) interval 2 C) interval 1 D) interval 4 E) interval 3

E) interval 3

4. Cancers develop stepwise over time because: A) All of these choices are correct. B) tumor cells divide slowly and in a stepwise pattern. C) it takes time for a tumor to dissolve through its encapsulation before it can invade neighboring tissues. D) cells keep leaving tumors and are destroyed in lymph nodes. E) it takes multiple mutations of multiple genes to allow cancer cells to develop.

E) it takes multiple mutations of multiple genes to allow cancer cells to develop.

57. Homologous pairs of chromosomes separate during: A) meiosis II only. B) meiosis I and mitosis. C) meiosis II and mitosis. D) mitosis only. E) meiosis I only

E) meiosis I only

82. Sister chromatids are separated during: A) meiosis II only. B) meiosis I and mitosis. C) mitosis only. D) meiosis I only. E) meiosis II and mitosis.

E) meiosis II and mitosis.

45. A skin cell in G2 of interphase has _____ as much DNA as it had in G1. A) four times B) half C) exactly D) one-fourth E) twice

E) twice

25. During the formation of female gametes, nondisjunction of X chromosomes may occur during meiosis I, resulting in two types of eggs with different compositions of sex chromosomes. If normal X or Y-bearing sperm fertilize these two types of egg, which of the options are possible sex chromosome complements in the resulting fertilized egg? A) XXX and XO or XXY and YO B) XX and XY or XYY and YO

the resulting fertilized egg? A) XXX and XO or XXY and YO