Ap bio final 1

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1

1. Which of the following compounds has 1°, 2°, 3° and 4° carbon atoms
A) hexane
B) 2-methylhexane
C) 2,2-dimethylhexane
D) 2,2,3-trimethylhexane

D

2
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2. Pick the set of terms that correctly classifies the compound.
A) tertiary amine, primary alkyl chloride, secondary alcohol
B) primary amine, primary alkyl chloride, secondary alcohol
C) primary amine, primary alkyl chloride, tertiary alcohol
D) secondary amine, primary alkyl chloride, secondary alcohol
E) secondary amine, secondary alkyl chloride, secondary alcohol

A

3

3. Chose a correct name for CH3(CH2)5CH3
A) Heptane
B) Pentane
C) Isoheptane
D) Isopentane
E) None of these

A

4

4. What is the chemical reaction mechanism by which cells make polymers from monomers?

A) ionic bonding of monomers
B) phosphodiester linkages
C) hydrolysis
D) dehydration reactions
E) the formation of disulfide bridges between monomers

C

5

5. The molecular formula for glucose is C6H1206. What would be the molecular formula for a molecule made by linking three glucose molecules together by dehydration reactions?

A) C18 H32 016
B) C18 H10 O15
C) C18 H36 018
D)C3 H6 O3
E) C6 H10 O5

B

6

6. On food packages, to what does the term insoluble fiber refer?

A) amylopectin
B) cellulose
C) chitin
D) polypeptides
E) starch

B

7

7. Which of the following is true of cellulose?

A) It is a polymer composed of enantiomers of glucose, it is a storage polysaccharide for energy in plant cells, it is digestible by bacteria in the human gut, and it is a major component of plant cell walls.
B) It is digestible by bacteria in the human gut.
C) It is a major structural component of plant cell walls.
D) It is a storage polysaccharide for energy in plant cells.
E) It is a polymer composed of enantiomers of glucose.

C

8

8. Misfolding of polypeptides is a serious problem in cells. Which of the following diseases are
associated with an accumulation of misfolded polypeptides?

A) diabetes mellitus only
B) Alzheimer's and Parkinson's only
C) Alzheimer's, Parkinson's, and diabetes mellitus
D) Parkinson's only
E) Alzheimer's only

B

9

9. What methods may be used to elucidate the structures of purified proteins?

A) X-ray crystallography
B) both X-ray crystallography and NMR spectroscopy
C) NMR spectroscopy
D) bioinformatics
E) analysis of amino acid sequence of small fragments

D

10

10. Which of the following techniques uses the amino acid sequences of polypeptides to predict a protein's threedimensional structure?

A) bioinformatics
B) analysis of amino acid sequence of small fragments
C) NMR spectroscopy
D) high-speed centrifugation
E) X-ray crystallography

A

11

11. DNAase is an enzyme that catalyzes the hydrolysis of the covalent bonds that join nucleotides together. What would first happen to DNA molecules treated with DNAase?

A) The two strands of the double helix would separate.
B) The phosphodiester bonds between deoxyribose sugars would be broken.
C) The purines would be separated from the deoxyribose sugars.
D) The pyrimidines would be separated from the deoxyribose sugars.
E) All bases would be separated from the deoxyribose sugars.

B

12

12. The difference between the sugar in DNA and the sugar in RNA is that the sugar in DNA

A) is a six-carbon sugar and the sugar in RNA is a five-carbon sugar.
B) can form a double-stranded molecule.
C) is an aldehyde sugar and the sugar in RNA is a keto sugar.
D) is in the α configuration and the sugar in RNA is in the β configuration.
E) contains one less oxygen atom.

E

13

13. If cells are grown in a medium containing radioactive ³²P-labeled phosphate, which of these molecules will be labeled?

A) phospholipids
B) nucleic acids
C) proteins
D) amylose
E) both phospholipids and nucleic acids

E

14
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14. Which of the following molecules contain(s) an aldehyde type of carbonyl functional group?

A) 1
B) 4
C) 8
D) 10
E) 1 and 4

E

15
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15. Which molecule is a saturated fatty acid?

A) 1
B) 5
C) 6
D) 8
E) 9

E

16
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16. Which of the following molecules is an amino acid with a hydrophobic R group or side chain?

A) 3
B) 7
C) 8
D) 12
E) 13

B

17
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17. Which of the following statements is false?

A) Molecules 1 and 4 could be joined together by a glycosidic linkage to form a disaccharide.
B) Molecules 9 and 10 could be joined together by ester bonds to form a triacylglycerol.
C) Molecules 2 and 7 could be joined together to form a short peptide.
D) Molecules 2, 7, and 8 could be joined together to form a short peptide.
E) Molecules 14 and 15 could be joined together to form a polypeptide.

E

18

Approximately 32 different monomeric carbohydrate subunits are found in various natural polysaccharides. Proteins are composed of 20 different amino acids. DNA and RNA are each synthsized from four nucleotides.

18. Professor Jamey Marth at the University of California, Santa Barbara, identified 70 molecules that are used to build cellular macromolecules and structures. These include at least 34 saccharides, 8 nucleosides, and 20 amino acids. In theory, then, which class of biological polymer has the greatest information-coding capacity?

A) polysaccharides
B) proteins
C) DNA
D) RNA

A

19

Approximately 32 different monomeric carbohydrate subunits are found in various natural polysaccharides. Proteins are composed of 20 different amino acids. DNA and RNA are each synthsized from four nucleotides.

19. The primary function of polysaccharides attached to the glycoproteins and glycolipids of animal cell membranes is

A) to facilitate diffusion of molecules down their concentration gradients.
B) to actively transport molecules against their concentration gradients.
C) to maintain the integrity of a fluid mosaic membrane.
D) to maintain membrane fluidity at low temperatures.
E) to mediate cell-to-cell recognition.

E

20

20. In a paramecium, cell surface integral membrane proteins are synthesized

A) in the cytoplasm by free ribosomes.
B) by ribosomes in the nucleus.
C) by ribosomes bound to the rough endoplasmic reticulum.
D) by ribosomes in the Golgi vesicles.
E) by ribosomes bound to the inner surface of the plasma membrane.

C

21

21. When a plant cell, such as one from a peony stem, is submerged in a very hypotonic solution, what is likely to occur?

A) The cell will burst.
B) The cell membrane will lyse.
C) Plasmolysis will shrink the interior.
D) The cell will become flaccid.
E) The cell will become turgid.

E

22

22. Glucose diffuses slowly through artificial phospholipid bilayers. The cells lining the small intestine, however, rapidly move large quantities of glucose from the glucose-rich food into their glucose-poor cytoplasm. Using this information, which transport mechanism is most probably functioning in the intestinal cells?

A) simple diffusion
B) phagocytosis
C) active transport pumps
D) exocytosis
E) facilitated diffusion

E

23

23. The movement of potassium into an animal cell requires

A) low cellular concentrations of sodium.
B) high cellular concentrations of potassium.
C) an energy source such as ATP.
D) a cotransport protein.
E) a potassium channel protein.

C

24

24. Several epidemic microbial diseases of earlier centuries incurred high death rates because they resulted in severe dehydration due to vomiting and diarrhea. Today they are usually not fatal because we have developed which of the following?

A) antiviral medications that are efficient and work well with all viruses
B) antibiotics against the viruses in question
C) intravenous feeding techniques
D) medication to prevent blood loss
E) hydrating drinks that include high concentrations of salts and glucose

E

25
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The solutions in the two arms of this U-tube are separated by a membrane that is permeable to water and glucose but not to sucrose. Side A is half-filled with a solution of 2 M sucrose and 1 M glucose. Side B is half-filled with 1 M sucrose and 2 M glucose. Initially, the liquid levels on both sides are equal.

25. Initially, in terms of tonicity, the solution in side A with respect to that in side B is
A) hypotonic.
B) plasmolyzed.
C) isotonic.
D) saturated.
E) hypertonic.

C

26

26. In an HIV-infected cell producing HIV virus particles, the viral glycoprotein is expressed on the plasma membrane. How do the viral glycoproteins get to the plasma membrane?

A) They are synthesized on ribosomes on the plasma membrane.
B) They are synthesized by ribosomes in the rough ER, and arrive at the plasma membrane in the membrane of secretory vesicles.
C) They are synthesized on free cytoplasmic ribosomes, and then inserted into the plasma membrane.
D) They are synthesized by ribosomes in the rough ER, secreted from the cell, and inserted into the plasma membrane from the outside.
E) They are synthesized by ribosomes on the HIV viral membrane, which fuses with the plasma membrane from inside the cell.

B

27

27. A patient has had a serious accident and lost a lot of blood. In an attempt to replenish body fluids, distilled water–equal to the volume of blood lost–is transferred directly into one of his veins. What will be the most probable result of this transfusion?

A) It will have no unfavorable effect as long as the water is free of viruses and bacteria.
B) The patient's red blood cells will shrivel up because the blood fluid has become hypotonic compared to the cells.
C) The patient's red blood cells will swell because the blood fluid has become hypotonic compared to the cells.
D) The patient's red blood cells will shrivel up because the blood fluid has become hypertonic compared to the cells.
E) The patient's red blood cells will burst because the blood fluid has become hypertonic compared to the cells.

C

28

28. When a glucose molecule loses a hydrogen atom as a result of an oxidation-reduction reaction, the molecule becomes

A) hydrolyzed
B) hydrogenated
C) oxidized
D) reduced
E) an oxidizing agent

C

29

29. Which process in eukaryotic cells will proceed normally whether oxygen (O₂) is present or absent?

A) electron transport
B) glycolysis
C) the citric acid cycle
D) oxidative phosphorylation
E) chemiosmosis

B

30

30. An electron loses potential energy when it

A) shifts to a less electronegative atom
B) shifts to a more electronegative atom
C) increases in kinetic energy
D) increases it's activity as an oxidizing agent
E) moves further away from the nucleus of the atom

B

31

31. How many carbon atoms are fed into the citric acid cycle as a result of the oxidation of one molecule of pyruvate?

A) two
B) four
C) six
D) eight
E) ten

A

32

32. What fraction of the carbon dioxide exhaled by animals is generated by the reactions of the citric acid cycle, if glucose is the sole energy source?

A) 1/6
B) 1/3
C) 1/2
D) 2/3
E) 100/100

D

33

33. In chemiosmotic phosphorylation, what is the most direct source of energy that is used to convert ADP + Pi to ATP?

A) energy released as electrons flow through the electron transport system
B) energy released from substrate-level phosphorylation
C) energy released from movement of protons through ATP synthase, against the electrochemical gradient
D) energy released from movement of protons through ATP synthase, down the electrochemical gradient
E) No external source of energy is required because the reaction is exergonic.

D

34

34. Energy released by the electron transport chain is used to pump H⁺ into which location in eukaryotic cells?

A) cytosol
B) mitochondrial outer membrane
C) mitochondrial inner membrane
D) mitochondrial intermembrane space
E) mitochondrial matrix

D

35

35. Chemiosmotic ATP synthesis (oxidative phosphorylation) occurs in

A) all cells, but only in the presence of oxygen.
B) only eukaryotic cells, in the presence of oxygen.
C) only in mitochondria, using either oxygen or other electron acceptors.
D) all respiring cells, both prokaryotic and eukaryotic, using either oxygen or other electron acceptors.
E) all cells, in the absence of respiration.

D

36

36. In a mitochondrion, if the matrix ATP concentration is high, and the intermembrane space proton concentration is too low to generate sufficient proton-motive force, then

A) ATP synthase will increase the rate of ATP synthesis.
B) ATP synthase will stop working.
C) ATP synthase will hydrolyze ATP and pump protons into the intermembrane space.
D) ATP synthase will hydrolyze ATP and pump protons into the matrix.

C

37

37. Which of the following normally occurs regardless of whether or not oxygen (O₂) is present?

A) glycolysis
B) fermentation
C) oxidation of pyruvate to acetyl CoA
D) citric acid cycle
E) oxidative phosphorylation (chemiosmosis)

A

38

38. In alcohol fermentation, NAD⁺ is regenerated from NADH by

A) reduction of acetaldehyde to ethanol (ethyl alcohol).
B) oxidation of pyruvate to acetyl CoA.
C) reduction of pyruvate to form lactate.
D) oxidation of ethanol to acetyl CoA.
E) reduction of ethanol to pyruvate.

A

39

39. What carbon sources can yeast cells metabolize to make ATP from ADP under anaerobic conditions?

A) glucose
B) ethanol
C) pyruvate
D) lactic acid
E) either ethanol or lactic acid

A

40
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40. Which portion of the pathway in Figure 9.1 involves an endergonic reaction?

A) A
B) B
C) C
D) D
E) E

A

41

41. If photosynthesizing green algae are provided with CO2 synthesized with heavy oxygen (18O), later analysis will show that all but one of the following compounds produced by the algae contain the 18O label. That one is

A) 3-phosphoglycerate
B) glyceraldehyde 3-phosphate (G3P)
C) glucose
D) ribulose biphosphate (RuBP)
E) O2

E

42

42. Which of the following are products of the light reactions of photosynthesis that are utilized in the Calvin cycle?

A) CO₂ and glucose
B) H₂O and O₂
C) ADP, Pi, and NADP⁺
D) electrons and H⁺
E) ATP and NADPH

E

43

43. Which of the events listed below occurs in the light reactions of photosynthesis?

A) NADP is produced.
B) NADPH is reduced to NADP⁺.
C) Carbon dioxide is incorporated into PGA.
D) ATP is phosphorylated to yield ADP.
E) Light is absorbed and funneled to reaction-center chlorophyll a.

E

44

44. As a research scientist, you measure the amount of ATP and NADPH consumed by the Calvin cycle in 1 hour. You find 30,000 molecules of ATP consumed, but only 20,000 molecules of NADPH. Where did the extra ATP molecules come from?

A) photosystem II
B) photosystem I
C) cyclic electron flow
D) linear electron flow
E) chlorophyll

C

45

45. In a plant cell, where are the ATP synthase complexes located?

A) thylakoid membrane only
B) plasma membrane only
C) inner mitochondrial membrane only
D) thylakoid membrane and inner mitochondrial membrane
E) thylakoid m

D

46

46. Which of the following statements best describes the relationship between photosynthesis and respiration?

A) Respiration runs the biochemical pathways of photosynthesis in reverse.
B) Photosynthesis stores energy in complex organic molecules, whereas respiration releases it.
C) Photosynthesis occurs only in plants and respiration occurs only in animals.
D) ATP molecules are produced in photosynthesis and used up in respiration.
E) Respira

B

47

47. In photosynthetic cells, synthesis of ATP by the chemiosmotic mechanism occurs during

A) photosynthesis only.
B) respiration only.
C) both photosynthesis and respiration.
D) neither photosynthesis nor respiration.
E) photorespiration only.

C

48

48. The phylogenetic distribution of the enzyme rubisco is limited to

A) C₃ plants only.
B) C₃ and C₄ plants.
C) all photosynthetic eukaryotes.
D) all known photoautotrophs, both bacterial and eukaryotic.
E) all living cells

D

49

49. Why are C₄ plants able to photosynthesize with no apparent photorespiration?

A) They do not participate in the Calvin cycle.
B) They use PEP carboxylase to initially fix CO₂.
C) They are adapted to cold, wet climates.
D) They conserve water more efficiently.
E) They exclude oxygen from their tissues.

B

50

50. CAM plants keep stomata closed in daytime, thus reducing loss of water. They can do this because they

A) fix CO₂ into organic acids during the night.
B) fix CO₂ into sugars in the bundle-sheath cells.
C) fix CO₂ into pyruvate in the mesophyll cells.
D) use the enzyme phosphofructokinase, which outcompetes rubisco for CO₂.
E) use photosystem I and photosystem II at night.

A

51

51. Photorespiration lowers the efficiency of photosynthesis by

A) carbon dioxide molecules.
B) 3-phosphoglycerate molecules.
C) ATP molecules.
D) ribulose bisphosphate molecules.
E) RuBP carboxylase molecules.

B

52
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52. Figure 10.1 shows the absorption spectrum for chlorophyll a and the action spectrum for photosynthesis. Why are they different?

A) Green and yellow wavelengths inhibit the absorption of red and blue wavelengths.
B) Bright sunlight destroys photosynthetic pigments.
C) Oxygen given off during photosynthesis interferes with the absorption of light.
D) Other pigments absorb light in addition to chlorophyll a.
E) Aerobic bacteria take up oxygen, which changes the measurement of the rate of photosynthesis.

D

53

Theodor W. Engelmann illuminated a filament of algae with light that passed through a prism, thus exposing different segments of algae to different wavelengths of light. He added aerobic bacteria and then noted in which areas the bacteria congregated. He noted that the largest groups were found in the areas illuminated by the red and blue light.

53. If you ran the same experiment without passing light through a prism, what would you predict?

A) There would be no difference in results.
B) The bacteria would be relatively evenly distributed along the algal filaments.
C) The number of bacteria present would decrease due to an increase in the carbon dioxide concentration.
D) The number of bacteria present would increase due to an increase in the carbon dioxide concentration

E) The number of bacteria would decrease due to a decrease in temperature of the water

B

54

54. For a newly evolving protist, what would be the advantage of using eukaryote-like cell division rather than binary fission?

A) Binary fission would not allow for the formation of new organisms.
B) Cell division would allow for the orderly and efficient segregation of multiple linear chromosomes.
C) Cell division would be faster than binary fission.
D) Cell division allows for lower rates of error per chromosome replication.
E) Binary fission would not allow the organism to have complex cells.

B

55

55. Suppose a biologist can separate one of a dozen pieces of chromatin from a eukaryotic (animal) nucleus. It might consist of which of the following?

A) one-twelfth of the genes of the organism
B) two chromosomes, each with six chromatids
C) a single circular piece of DNA
D) two long strands of DNA plus proteins
E) two chromatids attached together at a centromere

D

56

56. Where do the microtubules of the spindle originate during mitosis in both plant and animal cells?

A) centromere
B) centrosome
C) centriole
D) chromatid
E) kinetochore

B

57

57. Which of the following best describes how chromosomes move toward the poles of the spindle during mitosis?

A) The chromosomes are "reeled in" by the contraction of spindle microtubules.
B) Motor proteins of the kinetochores move the chromosomes along the spindle microtubules.
C) Nonkinetochore spindle fibers serve to push chromosomes in the direction of the poles.
D) The chromosomes are "reeled in" by the contraction of spindle microtubules, and motor proteins of the kinetochores move the chromosomes along the spindle microtubules.
E) The chromosomes are "reeled in" by the contraction of spindle microtubules, motor proteins of the kinetochores move the chromosomes along the spindle microtubules, and nonkinetochore spindle fibers serve to push chromosomes in the direction of the poles.

D

58

58. What is a cleavage furrow?

A) a ring of vesicles forming a cell plate
B) the separation of divided prokaryotes
C) a groove in the plasma membrane between daughter nuclei
D) the metaphase plate where chromosomes attach to the spindle
E) the space that is created between two chromatids during anaphase

C

59

59. Which of the following proteins are involved in binary fission as well as eukaryotic mitotic division?

A) cyclins
B) Cdks
C) MPF
D) actin and tubulin
E) cohesins

D

60

60. A plant-derived protein known as colchicine can be used to poison cells by blocking the formation of the spindle. Which of the following would result if colchicine is added to a sample of cells in G₂?

A) The cells would immediately die.
B) The cells would be unable to begin M and stay in G₂.
C) The chromosomes would coil and shorten but have no spindle to which to attach.
D) The chromosomes would segregate but in a disorderly pattern.
E) Each resultant daughter cell would also be unable to form a spindle.

C

61

61. Which of the following is a protein synthesized at specific times during the cell cycle that associates with a kinase to form a catalytically active complex?

A) PDGF
B) MPF
C) protein kinase
D) cyclin
E) Cdk

D

62

62. Which of the following triggers the cell's passage past the G₂ checkpoint into mitosis?

A) PDGF
B) MPF
C) protein kinase
D) cyclin
E) Cdk

B

63

63. Density-dependent inhibition is explained by which of the following?

A) As cells become more numerous, they begin to squeeze against each other, restricting their size and ability to produce control factors.
B) As cells become more numerous, the cell surface proteins of one cell contact the adjoining cells and they stop dividing.
C) As cells become more numerous, the protein kinases they produce begin to compete with each other, such that the proteins produced by one cell essentially cancel those produced by its neighbor.
D) As cells become more numerous, more and more of them enter the S phase of the cell cycle.
E) As cells become more numerous, the level of waste products increases, eventually slowing down metabolism.

B

64

64. The drug cytochalasin B blocks the function of actin. Which of the following aspects of the cell cycle would be most disrupted by cytochalasin B?

A) spindle formation
B) spindle attachment to kinetochores
C) DNA synthesis
D) cell elongation during anaphase
E) cleavage furrow formation and cytokinesis

E

65

65. Sturtevant provided genetic evidence for the existence of four pairs of chromosomes in Drosophila in which of these ways?

A) There are four major functional classes of genes in Drosophila.
B) Drosophila genes cluster into four distinct groups of linked genes.
C) The overall number of genes in Drosophila is a multiple of four.
D) The entire Drosophila genome has approximately 400 map units.
E) Drosophila genes have, on average, four different alleles.

B

66

66. Which of the following is the meaning of the chromosome theory of inheritance as expressed in the early 20th century?

A) Individuals inherit particular chromosomes attached to genes.
B) Mendelian genes are at specific loci on the chromosome and in turn segregate during meiosis.
C) Homologous chromosomes give rise to some genes and crossover chromosomes to other genes.
D) No more than a single pair of chromosomes can be found in a healthy normal cell.
E) Natural selection acts on certain chromosome arrays rather than on genes.

B

67

67. The centimorgan (cM) is a unit named in honor of Thomas Hunt Morgan. To what is it equal?

A) the physical distance between two linked genes
B) 1% frequency of recombination between two genes
C) 1 nanometer of distance between two genes
D) the distance between a pair of homologous chromosomes
E) the recombination frequency between two genes assorting independently

B

68

68. Which of the following two genes are closest on a genetic map of Drosophila?

A) b and vg
B) vg and cn
C) rb and cn
D) cn and b
E) b and rb

E

69

69. Of the following human aneuploidies, which is the one that generally has the most severe impact on the health of the individual?

A) 47, +21
B) 47, XXY
C) 47, XXX
D) 47, XYY
E) 45, X

A

70

70. A phenotypically normal prospective couple seeks genetic counseling because the man knows that he has a translocation of a portion of his chromosome 4 that has been exchanged with a portion of his chromosome 12. Although he is normal because his translocation is balanced, he and his wife want to know the probability that his sperm will be abnormal. What is your prognosis regarding his sperm?

A) 1/4 will be normal, 1/4 will have the translocation, and 1/2 will have duplications and deletions.
B) All will carry the same translocation as the father.
C) None will carry the translocation since abnormal sperm will die.
D) His sperm will be sterile and the couple might consider adoption.
E) 1/2 will be normal and the rest will have the father's translocation.

A

71

71. In 1956 Tijo and Levan first successfully counted human chromosomes. What is the reason it took so many years to do so?

A) Watson and Crick's structure of DNA was not done until 1953.
B) Chromosomes were piled up on top of one another in the nucleus.
C) Chromosomes were not distinguishable during interphase.
D) A method had not yet been devised to halt mitosis at metaphase.
E) Chromosomes were piled up on top of one another in the nucleus, chromosomes were not distinguishable during interphase, and a method had not yet been devised to halt mitosis at metaphase.

E

72

72. Genomic imprinting is generally due to the addition of methyl (–CH3) groups to C nucleotides in order to silence a given gene. If this depends on the sex of the parent who transmits the gene, which of the following must be true?

A) Methylation of C is permanent in a gene.
B) Genes required for early development stages must not be imprinted.
C) Methylation of this kind must occur more in males than in females.
D) Methylation must be reversible in ovarian and testicular cells.
E) The imprints are transmitted only to gamete-producing cells.

D

73

A man who is an achondroplastic dwarf with normal vision marries a color-blind woman of normal height. The man's father was 6 feet tall, and both the woman's parents were of average height. Achondroplastic dwarfism is autosomal dominant, and red-green color blindness is X-linked recessive.

73. What proportion of their sons would be color-blind and of normal height?

A) none
B) half
C) one out of four
D) three out of four
E) all

B

74

A man who is an achondroplastic dwarf with normal vision marries a color-blind woman of normal height. The man's father was 6 feet tall, and both the woman's parents were of average height. Achondroplastic dwarfism is autosomal dominant, and red-green color blindness is X-linked recessive.

74. They have a daughter who is a dwarf with normal color vision. What is the probability that she is heterozygous for both genes?

A) 0%
B) 25%
C) 50%
D) 75%
E) 100%

E

75
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A plantlike organism on the planet Pandora can have three recessive genetic traits: bluish leaves, due to an allele (a) of gene A; a feathered stem, due to an allele (b) of gene B; and hollow roots due to an allele (c) of gene C. The three genes are linked and recombine as follows:

A geneticist did a testcross with an organism that had been found to be heterozygous for the three recessive traits and she was able to identify progeny of the following phenotypic distribution (+ = wild type): (See Image)

75. Which of the following are the phenotypes of the parents in this cross?

A) 2 and 5
B) 1 and 6
C) 4 and 8
D) 3 and 7
E) 1 and 2

C

76
card image

A plantlike organism on the planet Pandora can have three recessive genetic traits: bluish leaves, due to an allele (a) of gene A; a feathered stem, due to an allele (b) of gene B; and hollow roots due to an allele (c) of gene C. The three genes are linked and recombine as follows:

A geneticist did a testcross with an organism that had been found to be heterozygous for the three recessive traits and she was able to identify progeny of the following phenotypic distribution (+ = wild type): (See Image)

76. The greatest distance among the three genes is between a and c. What does this mean?

A) Gene a is closest to b.
B) Genes are in the order: a–b–c.
C) Gene a is not recombining with c.
D) Gene a is between b and c.
E) Distance a–b is equal to distance a–c.

D

77

77. What is a ribozyme?

A) an enzyme that uses RNA as a substrate
B) an RNA with enzymatic activity
C) an enzyme that catalyzes the association between the large and small ribosomal subunits
D) an enzyme that synthesizes RNA as part of the transcription process
E) an enzyme that synthesizes RNA primers during DNA replication

B

78

Use the following model of a eukaryotic transcript to answer the next few questions.

5' UTR E₁ I₁ E₂ I₂ E₃ I₃ E₄ UTR 3'

78. Suppose that exposure to a chemical mutagen results in a change in the sequence that alters the 5' end of intron 1 (I₁). What might occur?

A) loss of the gene product
B) loss of E₁
C) premature stop to the mRNA
D) inclusion of I₁ in the mRNA
E) exclusion of E₂

D

79

79. Accuracy in the translation of mRNA into the primary structure of a polypeptide depends on specificity in the

A) binding of ribosomes to mRNA.
B) shape of the A and P sites of ribosomes.
C) bonding of the anticodon to the codon.
D) attachment of amino acids to tRNAs.
E) bonding of the anticodon to the codon and the attachment of amino acids to tRNAs.

E

80

80. An experimenter has altered the 3' end of the tRNA corresponding to the amino acid methionine in such a way as to remove the 3' AC. Which of the following hypotheses describes the most likely result?

A) tRNA will not form a cloverleaf.
B) The nearby stem end will pair improperly.
C) The amino acid methionine will not bind.
D) The anticodon will not bind with the mRNA codon.
E) The aminoacylsynthetase will not be formed.

C

81

81. What is the function of the release factor (RF)?

A) It separates tRNA in the A site from the growing polypeptide.
B) It binds to the stop codon in the A site in place of a tRNA.
C) It releases the amino acid from its tRNA to allow the amino acid to form a peptide bond.
D) It supplies a source of energy for termination of translation.
E) It releases the ribosome from the ER to allow polypeptides into the cytosol.

B

82

82. Why might a point mutation in DNA make a difference in the level of protein's activity?

A) It might result in a chromosomal translocation.
B) It might exchange one stop codon for another stop codon.
C) It might exchange one serine codon for a different serine codon.
D) It might substitute an amino acid in the active site.
E) It might substitute the N-terminus of the polypeptide for the C-terminus.

D

83

83. Which of the following is true of transcription in domain Archaea?

A) It is regulated in the same way as in domain Bacteria.
B) There is only one kind of RNA polymerase.
C) It is roughly simultaneous with translation.
D) Promoters are identical to those in domain Eukarya.
E) It terminates in a manner similar to bacteria.

C

84

84. Transcription of the structural genes in an inducible operon

A) occurs continuously in the cell.
B) starts when the pathway's substrate is present.
C) starts when the pathway's product is present.
D) stops when the pathway's product is present.
E) does not result in the production of enzymes.

B

85

85. Allolactose, an isomer of lactose, is formed in small amounts from lactose. An E. coli cell is presented for the first time with the sugar lactose (containing allolactose) as a potential food source. Which of the following occurs when the lactose enters the cell?

A) The repressor protein attaches to the regulator.
B) Allolactose binds to the repressor protein.
C) Allolactose binds to the regulator gene.
D) The repressor protein and allolactose bind to RNA polymerase.
E) RNA polymerase attaches to the regulator.

B

86

86. Altering patterns of gene expression in prokaryotes would most likely serve the organism's survival in which of the following ways?

A) organizing gene expression so that genes are expressed in a given order
B) allowing each gene to be expressed an equal number of times
C) allowing the organism to adjust to changes in environmental conditions
D) allowing young organisms to respond differently from more mature organisms
E) allowing environmental changes to alter the prokaryote's genome

C

87

87. If glucose is available in the environment of E. coli, the cell responds with a very low concentration of cAMP. When the cAMP increases in concentration, it binds to CAP. Which of the following would you expect to be a measurable effect?

A) decreased concentration of the lac enzymes
B) increased concentration of the trp enzymes
C) decreased binding of the RNA polymerase to sugar metabolism-related promoters
D) decreased concentration of alternative sugars in the cell
E) increased concentrations of sugars such as arabinose in the cell

E

88

88. During DNA replication,

A) all methylation of the DNA is lost at the first round of replication.
B) DNA polymerase is blocked by methyl groups, and methylated regions of the genome are therefore left uncopied.
C) methylation of the DNA is maintained because methylation enzymes act at DNA sites where one strand is already methylated and thus correctly methylates daughter strands after replication.
D) methylation of the DNA is maintained because DNA polymerase directly incorporates methylated nucleotides into the new strand opposite any methylated nucleotides in the template.
E) methylated DNA is copied in the cytoplasm, and unmethylated DNA is copied in the nucleus.

C

89

89. Gene expression might be altered at the level of post-transcriptional processing in eukaryotes rather than prokaryotes because of which of the following?

A) Eukaryotic mRNAs get 5' caps and 3' tails.
B) Prokaryotic genes are expressed as mRNA, which is more stable in the cell.
C) Eukaryotic exons may be spliced in alternative patterns.
D) Prokaryotes use ribosomes of different structure and size.
E) Eukaryotic coded polypeptides often require cleaving of signal sequences before localization.

C

90

90. Which of the following experimental procedures is most likely to hasten mRNA degradation in a eukaryotic cell?

A) enzymatic shortening of the poly-A tail
B) removal of the 5' cap
C) methylation of C nucleotides
D) methylation of histones
E) removal of one or more exons

B

91

91. Which of the following genes map out the basic subdivisions along the anterior-posterior axis of the Drosophila embryo?

A) homeotic genes
B) segmentation genes
C) egg-polarity genes
D) morphogens
E) inducers

B

92

92. BRCA1 and BRCA2 are considered to be tumor-suppressor genes because

A) they prevent infection by retroviruses that cause cancer.
B) their normal products participate in repair of DNA damage.
C) the mutant forms of either one of these promote breast cancer.
D) the normal genes make estrogen receptors.
E) they block penetration of breast cells by chemical carcinogens.

B

93

Suppose an experimenter becomes proficient with a technique that allows her to move DNA sequences within a prokaryotic genome

93. If she moves the operator to the far end of the operon (past the transacetylase gene), which of the following would likely occur when the cell is exposed to lactose?

A) The inducer will no longer bind to the repressor.
B) The repressor will no longer bind to the operator.
C) The operon will never be transcribed.
D) The structural genes will be transcribed continuously.
E) The repressor protein will no longer be produced.

D

94

A few decades ago, Knudsen and colleagues proposed a theory that, for a normal cell to become a cancer cell, a minimum of two genetic changes had to occur in that cell. Knudsen was studying retinoblastoma, a childhood cancer of the eye.

94. Two children are born from the same parents. Child one inherits a predisposition to retinoblastoma (one of the mutations) and child two does not. However, both children develop the retinoblastoma. Which of the following would you expect?

A) an earlier age of onset in child one
B) a history of exposure to mutagens in child one but not in child two
C) a more severe cancer in child one
D) increased levels of apoptosis in both children
E) decreased levels of DNA repair in child one

A

95

95. Cell differentiation always involves

A) the production of tissue-specific proteins, such as muscle actin.
B) the movement of cells.
C) the transcription of the myoD gene.
D) the selective loss of certain genes from the genome.
E) the cell's sensitivity to environmental cues, such as light or heat.

A

96

96. Which statement about the genomes of prokaryotes is correct?

A) Prokaryotic genomes are diploid throughout most of the cell cycle.
B) Prokaryotic chromosomes are sometimes called plasmids.
C) Prokaryotic cells have multiple chromosomes, "packed" with a relatively large amount of protein.
D) The prokaryotic chromosome is not contained within a nucleus but, rather, is found at the nucleolus.
E) Prokaryotic genomes are composed of circular DNA.

E

97

97. Prokaryotes' essential genetic information is located in the

A) nucleolus.
B) nucleoid.
C) nucleosome.
D) plasmids.
E) exospore.

B

98

98. Which of the following is an important source of endotoxin in gram-negative species?

A) endospore
B) sex pilus
C) flagellum
D) cell wall
E) capsule

D

99

99. Regarding prokaryotic genetics, which statement is correct?

A) Crossing over during prophase I introduces some genetic variation.
B) Prokaryotes feature the union of haploid gametes, as do eukaryotes.
C) Prokaryotes exchange some of their genes by conjugation, the union of haploid gametes, and transduction.
D) Mutation is a primary source of variation in prokaryote populations.
E) Prokaryotes skip sexual life cycles because their life cycle is too short.

D

100

100. Which of the following traits do archaeans and bacteria share?

1. composition of the cell wall
2. presence of plasma membrane
3. lack of a nuclear envelope
4. identical rRNA sequences

A) 1 only
B) 3 only
C) 1 and 3
D) 2 and 3
E) 2 and 4

D