Cell Bio Test 1 Review

64. What kind of membrane protein penetrates into the hydrophobic part of the lipid bilayer? a) integral protein b) lipid-anchored protein c) peripheral proteins d) transmembrane protein e) both integral protein and transmembrane protein

a) integral protein

14. Which of the following is a tenet of the Cell Theory? (Select all correct choices) a) All organisms are composed of one or more cells. b) The cell is the most basic structural unit of life. c) Cells can arise only by division from a preexisting cell. d) All cells reproduce by mitosis.

a) All organisms are composed of one or more cells. b) The cell is the most basic structural unit of life. c) Cells can arise only by division from a preexisting cell.

Which of these functional groups is the LEAST polar? Refer to Table 2.2 for more information if you are uncertain of the molecular structure of each one. a) CH3 b) OH c) COOH d) SH

a) CH3

47. You are studying a protein. It binds to elongating polypeptide chains as they emerge from an exit channel within the ribosome's large subunit. It appears to prevent partially formed or nascent polypeptides from binding to other proteins in the cytosol, which might cause them either to aggregate or misfold. What kind of proteins is this likely to be? a) Hsp70 chaperone b) TRiC chaperonin c) heat shock protein d) ribosomal protein

a) Hsp70 chaperone

77. You modify the gene for an integral membrane protein so that the cytoplasmic portions of the protein are deleted. When the gene is inserted in cells, what happens to the mobility of this protein in the membrane? a) It moves much greater distances than the intact protein. b) It moves much smaller distances than the intact protein. c) It does not move at all. d) It is not inserted into the membrane so nothing can be learned about their mobility. e) It flips to the opposite leaflet.

a) It moves much greater distances than the intact protein.

11. Which statement is NOT correct regarding Archaea? a) They are considered more closely related to bacteria than to Eukarya. b) Some are able to generate methane from carbon dioxide and hydrogen gases. c) Some are halophiles capable of surviving in a 5M osmolality. d) Some can survive temperatures above 120oC.

a) They are considered more closely related to bacteria than to Eukarya.

65. Why might integral membrane proteins be difficult to study based upon what you know of their amino acid composition? a) They are difficult to isolate in soluble form due to their hydrophobic transmembrane domains. b) They are difficult to isolate in soluble form due to their hydrophilic transmembrane domains. c) They are too small. d) They are too large. e) None of these are correct.

a) They are difficult to isolate in soluble form due to their hydrophobic transmembrane domains.

86. An important aspect of transport by facilitated transporters (carriers) and pumps is ________. a) a conformational shift in the protein structure b) rigidity c) membrane fluidity d) α-helix secondary structure e) β-pleated sheet secondary structure

a) a conformational shift in the protein structure

76. Enzymes that move certain phospholipids between leaflets also have which of the following properties? a) able to establish and maintain membrane lipid asymmetry b) interact with neighboring epithelial cells, or the basal membrane c) block post-synaptic membrane signals d) transport proteins across the membrane e) all of the above

a) able to establish and maintain membrane lipid asymmetry

61. People who have the A blood type possess ________. a) an enzyme that adds an N-acetylgalactosamine to the end of the oligosaccharide chain on RBC membrane glycolipids b) an enzyme that adds a galactose to the end of the oligosaccharide chain on RBC membrane glycolipids c) an enzyme that adds phospholipids to the end of the oligosaccharide chain on RBC membrane glycolipids d) no enzymes capable of attaching galactose or N-acetylgalactosamine to the end of the oligosaccharide chain on RBC membrane glycolipids e) both an enzyme that adds an N-acetylgalactosamine to the end of the oligosaccharide chain on RBC membrane glycolipids and an enzyme that adds a galactose to the end of the oligosaccharide chain on RBC membrane glycolipids

a) an enzyme that adds an N-acetylgalactosamine to the end of the oligosaccharide chain on RBC membrane glycolipids

12. Which feature is shared by both prokaryotic and eukaryotic cells? a) complex chromosomes capable of forming condensed chromatin b) complex cilia and flagella c) photosystems housed in chloroplast membranes d) cell division employing a mitotic spindle e) diploid chromosomes inherited from several parents

a) complex chromosomes capable of forming condensed chromatin

62. What kind of membrane protein penetrates into the hydrophobic part of the lipid bilayer? a) integral protein b) lipid-anchored protein c) peripheral protein d) phosphatidylcholine e) galactocerebroside

a) integral protein

35. Which of these amino acids is most likely to be found in the core of a protein? a) methionine b) asparagine c) serine d) threonine e) glutamic acid

a) methionine

87. The sodium-potassium pump makes the cell interior more _________ by pumping _______ sodium ions out of the cell for every ___________ potassium ions pumped in. a) negative, 3, 2 b) negative, 2, 3 c) positive, 3, 2 d) positive, 2, 3 e) negative, 4, 3

a) negative, 3, 2

16. Inert biological molecules like fats and waxes are chemically characterized by possessing many: a) non-polar covalent bonds b) ionic bonds and hydrogen bonds c) polar covalent bonds d) oxygen, nitrogen or sulfur atoms

a) non-polar covalent bonds

49. Biological roles for carbohydrates include: (Select all that apply) a) structural molecules b) catalytic molecules c) energy storage molecules d) repositories of genetic information

a) structural molecules c) energy storage molecules

71. The temperature at which a lipid bilayer shifts from a fluid state to a crystalline gel is called the _____________. a) transition temperature b) temperature optimum c) transition series d) pH optimum e) gelation temperature

a) transition temperature

44. Which lipid is most likely to remain solid at room temperature? a) tristearate b) vegetable oil c) polyunsaturated fat d) linseed oil

a) tristearate

83. A channel that opens in response to changes in ionic charge across a membrane is called a ________. a) voltage-gated channel b) charge-gated channel c) ligand-gated channel d) positive-gated channel e) electric-gated channel

a) voltage-gated channel

51. Select the correct statements regarding carbohydrate structure: (Select all that apply) a) If the carbonyl group of a sugar has an internal placing, the sugar is termed a ketose, such as glucose. b) If the carbonyl group of a sugar has an internal placing, the sugar is termed a ketose, such as fructose. c) If the carbonyl group of a sugar has a terminal placing, the sugar is termed an aldose, such as glucose. d) If the carbonyl group of a sugar has a terminal placing, the sugar is termed an aldose, such as fructose.

b) If the carbonyl group of a sugar has an internal placing, the sugar is termed a ketose, such as fructose. c) If the carbonyl group of a sugar has a terminal placing, the sugar is termed an aldose, such as glucose.

60. Why did liposomes not work against diseases as hoped when they were first tried? a) They were not stable enough to last until their target destination. b) Immune system phagocytes removed them from the bloodstream before they could exert an effect. c) They could not hold water soluble and lipid soluble drugs. d) They were targeted incorrectly. e) They expanded osmotically and lysed before reaching their target.

b) Immune system phagocytes removed them from the bloodstream before they could exert an effect.

88. What is the distinguishing characteristic of a P-type pump? a) It must be pumped during the cycle. b) It must be phosphorylated during the cycle. c) It must be protonated during the cycle. d) It must be methylated during the cycle. e) It must be acetylated during the cycle.

b) It must be phosphorylated during the cycle.

78. What happens to phospholipid mobility when the cell is treated with agents that disrupt the underlying membrane skeleton? a) Mobility is unchanged. b) Mobility is increased because the fences that normally restrict their diffusion are removed. c) Mobility is decreased because the fences that normally restrict their diffusion are removed. d) Mobility is increased because the treatment raises the temperature. e) Mobility is decreased because the treatment lowers the temperature.

b) Mobility is increased because the fences that normally restrict their diffusion are removed.

89. In the Na+/glucose cotransporter, _________ moving down its gradient drives the transport of __________ against its gradient. a) Na+ ions, K+ ions b) Na+ ions, glucose c) glucose, Na+ ions d) glucose, K+ ions e) K+ ions, glucose

b) Na+ ions, glucose

50. Which of these functional groups would make a biochemical more soluble in water? (Select all that apply) a) CH3 b) OH c) COOH d) SH

b) OH c) COOH

73. While culturing some cells, you lower the temperature of the culture. What happens immediately to the membrane fluidity? a) Nothing happens. b) The membrane becomes less fluid. c) The membrane becomes more fluid. d) The membrane fluidity fluctuates back and forth from high to low. e) The membrane fluidity fluctuates back and forth from low to high.

b) The membrane becomes less fluid.

34. How do amino acids like hydroxylysine and thyroxine, which are not among the 20 amino acids inserted into amino acid chains, get into proteins? a) They are inserted due to mutations. b) They are the result of the alteration of R groups of the 20 amino acids after their incorporation into the polypeptide. c) They occur as carboxyl groups are altered, reversing the chirality of the molecules. d) Insertion of the amino acid into the polypeptide causes bonds to break and new amino acids to form.

b) They are the result of the alteration of R groups of the 20 amino acids after their incorporation into the polypeptide.

66. On average, how many amino acids, forming a hydrophobic α-helix, does it take to cross the hydrophobic part of the membrane? a) about 10 amino acids b) about 20 amino acids c) at least 40 amino acids d) about 2-3 amino acids e) None of these are correct.

b) about 20 amino acids

30. Carbon's suitability as the molecular framework for biochemicals stems from its: a) large nucleus containing a high ratio of neutrons b) almost full outer shell of electrons, allowing for the formation of linear, branched and cyclic molecules c) ability to form elongated polymers d) high electronegativity

b) almost full outer shell of electrons, allowing for the formation of linear, branched and cyclic molecules

42. Examine the structures of cholesterol, testosterone and estrogen shown in Figure 2.23 (Or provide the figure for the Q). If we know that cholesterol is the precursor for synthesizing the other sex hormones, which of the statements below is likely to be CORRECT? a) cholesterol will require demethylation to be converted into testosterone but not to be converted into estrogen b) cholesterol will require demethylation to be converted into both testosterone and estrogen c) cholesterol will require demethylation to be converted into estrogen but not to be converted into testosterone d) all statements are incorrect

b) cholesterol will require demethylation to be converted into both testosterone and estrogen

53. If an organism lives in an environment where significant temperature fluctuations occur, and is capable of altering the fatty acid composition of its phospholipid bilayer, which of these choices would best allow membrane integrity to remain stable? (Select all that apply) a) increasing stearic acid incorporation during cold weather b) decreasing stearic acid incorporation during cold weather c) increasing stearic acid incorporation during hot weather d) decreasing stearic acid incorporation during hot weather

b) decreasing stearic acid incorporation during cold weather c) increasing stearic acid incorporation during hot weather

58. What are the building blocks of a phosphoglyceride, specifically phosphatidic acid? a) glycerol + 2 phosphate groups + 1 fatty acid b) glycerol + 1 phosphate group + 2 fatty acids c) glycerol + 1 phosphate group d) glycerol + 3 fatty acids e) glycerol + 1 phosphate group + 3 fatty acids

b) glycerol + 1 phosphate group + 2 fatty acids

79. Which protein in the red blood cell membrane appears to be responsible for the exchange of bicarbonate ions and chloride ions across the red blood cell membrane? a) glycophorin A b) glycophorin D c) band 3 d) glyceraldehyde 3-phosphate e) alpha-actinin

b) glycophorin D

63. What kind of membrane protein is found entirely outside the bilayer on either the extracellular or cytoplasmic surface and is covalently linked to a membrane lipid situated within the bilayer? a) integral protein b) lipid-anchored protein c) peripheral proteins d) carbohydrate-anchored protein e) transmembrane

b) lipid-anchored protein

25. A release of hydrogen ions to a solution would most likely ____________. a) raise pH b) lower pH c) buffer pH d) change salinity e) not affect pH

b) lower pH

82. The movement of water through a semipermeable membrane from a region of lower solute concentration to a region of higher solute concentration is called ________. a) diffusion b) osmosis c) denaturation d) metabolism e) solubility

b) osmosis

18. Which of the following elements are commonly found in biological molecules and strongly electronegative? a) oxygen and carbon b) oxygen and phosphorus c) oxygen and nitrogen d) carbon and nitrogen e) carbon and sodium

b) oxygen and phosphorus

17. Which of these bonds results from an unequal sharing of electrons? a) ionic bond b) polar covalent bond c) hydrogen bond d) nonpolar covalent bond

b) polar covalent bond

55. RNA and DNA NEVER differ in the functional groups attached to: (Select all that apply) a) the 1' carbon b) the 3' carbon c) the 2' carbon d) the 5'carbon

b) the 3' carbon d) the 5'carbon

26. A buffer has all of the following characteristics EXCEPT: a) the ability to protect cells from fluctuations in pH b) the ability to protect cells from fluctuations in temperature c) able to react with hydrogen ions d) able to react with hydroxyl ions

b) the ability to protect cells from fluctuations in temperature

13. Which statement is NOT correct when describing eukaryotic and bacterial flagella? a) they generate movement by different mechanisms b) the bacterial flagellum is more complex c) the eukaryotic flagellum is not found on all cells d) the bacterial flagellum can rotate at speeds greater than 1,000 rotations per second e) all flagella allow cells possessing them to exhibit motility

b) the bacterial flagellum is more complex

22. Where are hydrophobic interactions most likely to occur? a) on the surface of a water-soluble protein b) the core of a water-soluble protein c) in contact with water molecules d) between two charged molecules e) between two ions

b) the core of a water-soluble protein

33. Why do sugars tend to be highly water soluble? a) they have only a few hydroxyl groups b) they have large numbers of hydroxyl groups c) they have large numbers of sulfhydryl groups d) they have large numbers of methyl groups e) they have small molecular weights

b) they have large numbers of hydroxyl groups

32. Which polysaccharide bond cannot be broken by mammalian enzymes that normally digest polysaccharides? a) α(1—>4) glycosidic linkages b) β(1—>4) glycosidic linkages c) α(1—>6) glycosidic linkages d) β(1—>6) glycosidic linkages e) phosphate ester linkages

b) β(1—>4) glycosidic linkages

8. Which of the following is NOT a model organism used for understanding basic processes of life? a) Mus musculus b) Drosophila melanogaster c) Homo sapiens d) Arabidopsis thaliana e) Caenorhabditis elegans

c) Homo sapiens

57. What evidence convinced Overton that membranes were composed of lipids? a) He could see the lipids in the microscope. b) Membranes were destroyed by enzymes that degraded lipids. c) More lipid-soluble solutes entered root hair cells faster than polar solutes. d) Membranes dissolved in gasoline. e) Membranes did not dissolve in water.

c) More lipid-soluble solutes entered root hair cells faster than polar solutes.

29. Which of the following tripeptides would be most likely to be soluble in an organic (hydrophobic) solvent like benzene? a) N - phenylalanine - alanine - glycine - C b) N - leucine - alanine - lysine - C c) N - proline - phenylalanine - leucine - C d) N - arginine - lysine - proline - C e) N - glutamate - aspartate - glycine - C

c) N - proline - phenylalanine - leucine - C

46. You are working with an enzyme that you can denature in the presence of urea. However, the enzyme is not denatured by the addition of mercaptoethanol. What would that suggest to you about the enzyme? a) The enzyme probably contained no positively charged amino acids since these are neutralized by mercaptoethanol. b) The enzyme probably contained no acidic amino acids since these are neutralized by mercaptoethanol. c) The enzyme probably contained no disulfide linkages since mercaptoethanol breaks such linkages. d) Mercaptoethanol and urea denature enzymes in the same manner, so the observation lacks significance.

c) The enzyme probably contained no disulfide linkages since mercaptoethanol breaks such linkages.

41. Fatty acids with a polar carboxyl group and a nonpolar hydrocarbon chain are considered ___________________ molecules. a) entirely hydrophobic b) entirely hydrophilic c) amphipathic d) highly-reactive

c) amphipathic

59. What word describes a molecule that contains both hydrophilic and hydrophobic portions? a) cyclic b) stereoisomer c) amphipathic d) aromatic e) amphoteric

c) amphipathic

52. Select the durable structural polysaccharides from the choices provided. (Select all that apply) a) glucose b) starch c) cellulose d) chitin e) glycosaminoglycan

c) cellulose d) chitin

69. An amino acid is made to replace another amino acid in membrane-spanning α-helices by site-directed mutagenesis of the gene coding for the protein. This is done in order to determine how close together two such α-helices are in the structure of an integral protein. The amino acid is added to facilitate the attachment of a nitroxide group which can be used to detect position The amino acid substituted is:____________________. a) phenylalanine b) alanine c) cysteine d) methionine e) proline

c) cysteine

81. _________ is the movement of a substance from an area of high concentration to an area of lower concentration. a) denaturation b) osmosis c) diffusion d) secondary active e) active transport

c) diffusion

37. Proteins are often composed of two or more distinct modules that fold up independently of one another. They often represent parts of a protein that function in a semi-independent manner. These modules are called ______. a) protein motifs b) secondary structures c) domains d) C-terminus

c) domains

40. Which of these statements regarding glyceraldehyde is NOT correct? a) glyceraldehyde stereoisomers exhibit optical activity by rotating plane-polarized light in opposite directions b) glyceraldehyde stereoisomers cannot be superimposed on one another c) glyceraldehyde is one of several three-carbon aldoses d) glyceraldehyde's second carbon is covalently bound to H, OH, CHO and COOH groups

c) glyceraldehyde is one of several three-carbon aldoses

24. Water's life-supporting properties include all of the following EXCEPT: a) high boiling point compatible with temperate extremes of summer allowing energy to be released through sweat b) protection from cold and damaging radiation by providing the matrix around which the cellular framework is constructed. c) high probability of bonding with nonpolar molecules d) ability to dissociate into OH- and H+ units within the cell

c) high probability of bonding with nonpolar molecules

21. Which interaction is most important in enhancing the solubility of macromolecules in water? a) hydrophobic interactions b) nonpolar covalent bonds c) hydrogen bonds d) van der Waals forces e) Both hydrophobic interactions and nonpolar covalent bonds

c) hydrogen bonds

85. A channel that opens in response to the binding of a specific molecule, which is usually not the solute that passes through the channel is called a ________. a) voltage-gated channel b) charge-gated channel c) ligand-gated channel d) positive-gated channel e) electric-gated channel

c) ligand-gated channel

72. Which property of membranes allows interactions like the assembly of membrane protein clusters at particular sites and the formation of specialized structures to take place within the membrane? a) hydrophobicity b) hydrophilicity c) membrane fluidity d) their amphipathic nature e) their amphoteric nature

c) membrane fluidity

75. When membrane lipids are extracted from cells and used to prepare artificial lipid bilayers, cholesterol and sphingolipids tend to self-assemble into ________ that are more gelated and highly ordered than surrounding regions consisting primarily of _________. a) macrodomains, phosphoglycerides b) microdomains, integral proteins c) microdomains, phosphoglycerides d) liquid crystals, phosphoglycerides e) liquid crystals, microdomains

c) microdomains, phosphoglycerides

3. The apical ends of intestinal cells face the intestinal channel and have long processes that facilitate the absorption of nutrients. What is the name of these processes and what cytoskeletal element comprises their internal skeleton? a) microvilli, microtubules b) villi, microtubules c) microvilli, actin filaments d) villi, actin filaments e) microvilli, intermediate filaments

c) microvilli, actin filaments

28. The low-molecular-weight building blocks of polymers are called _______. a) minipolymers b) monoblocks c) monomers d) portions e) octamers

c) monomers

27. At higher proton concentrations, proteins are likely to possess: a) more NH2 groups and more NH3+ groups b) fewer NH2 groups and fewer NH3+ groups c) more NH2 groups and fewer NH3+ groups d) fewer NH2 groups and more NH3+ groups

c) more NH2 groups and fewer NH3+ groups

9. What is the most appropriate unit of measurement for macromolecular complexes including ribosomes and microfilaments? a) picometers b) angstroms c) nanometers d) micrometers e) centimeters

c) nanometers

84. What is thought to be important in maintaining the native structure of the Kv channel membrane protein and promoting its function as a voltage-gated channel? a) negatively charged cholesterol b) positively charged sphingolipids c) negatively charged phospholipids d) positively charged phospholipids e) negatively charged sphingolipids

c) negatively charged phospholipids

6. The genetic material of a prokaryotic cell is present in the _________, a poorly defined region of the cell that lacks a boundary membrane to separate it from the surrounding cytoplasm. a) nucleus b) plasma membrane c) nucleoid region d) ribosome e) miticondrion

c) nucleoid region

67. What characterizes the amino acids that are found in an α-helical segment that spans a membrane? a) exclusively circular b) predominantly hydrophilic c) predominantly hydrophobic d) predominantly antiparallel e) totally parallel

c) predominantly hydrophobic

48. A single-ringed nitrogenous base found in nucleic acid precursors is termed a ___________________. a) nucleoside b) nucleotide c) pyrimidine d) purine

c) pyrimidine

70. Which of the following is NOT an observed function of peripheral proteins? a) mechanical support for membrane b) enzyme activity c) receptor activity d) anchor for integral proteins e) factors that transmit transmembrane signals

c) receptor activity

54. You treat a partially purified preparation of protein with a reagent that breaks bonds between sulfur atoms. Which level(s) of protein structure are most likely to be affected? (Select all that apply) a) primary b) secondary c) tertiary d) quaternary

c) tertiary d) quaternary

38. What level of structure in proteins is held together by R group interactions between different polypeptides? a) primary structure b) secondary structure c) tertiary structure d) quaternary structure

c) tertiary structure

31. What bond is responsible for the branch points in glycogen and amylopectin? a) α(1—>4) glycosidic linkages b) β(1—>4) glycosidic linkages c) α(1—>6) glycosidic linkages d) β(1—>6) glycosidic linkages e) 3'-5' phosphodiester linkages

c) α(1—>6) glycosidic linkages

36. What type of protein secondary structure is characterized as being highly extensible because of its coiled structure? a) β-pleated sheet b) proline kink c) α-helix d) globular

c) α-helix

1. Despite being correct about the first two tenets of the Cell Theory, Schleiden and Schwann made an error about another central feature of cells. What was their mistaken claim? a) They believed that all cells were smaller than 2 µ in diameter. b) They claimed that all cells were exactly the same in every detail. c) They described cells as immortal. d) They believed that cells could arise from noncellular materials. e) They stated that all cells had nuclei through their entire existence.

d) They believed that cells could arise from noncellular materials.

45. You discover a novel protozoan which seems able to exist in the extreme salinity of the Dead Sea. Comparative examination of its enzyme structures against those of non-halophilic protozoa are most likely to reveal that ________________. a) the novel protozoan possesses enzymes where the outer protein surface has many acidic amino acid residues b) the novel protozoan possesses enzymes where the outer protein surface has many nonpolar amino acid residues c) the novel protozoan possesses enzymes where the outer protein surface has many cysteine-associated disulfide bridges d) all are equally likely possibilities

d) all are equally likely possibilities

68. Using the nucleotide sequence of a gene, which of the following can be learned from a computer-based (computational) analysis of the primary amino acid structure of a membrane protein? a) its structure b) its orientation within the lipid bilayer c) its concentration in each cell d) both its structure and its orientation within the lipid bilayer

d) both its structure and its orientation within the lipid bilayer

7. Some bacteria can pass a piece of DNA from a donor bacterial cell to a recipient bacterial cell through a structure called a pilus. What is this process called? a) translocation b) transduction c) transformation d) conjugation e) binary fission

d) conjugation

10. What is the most appropriate unit of measurement for the diameter of most types of cells? a) picometers b) angstroms c) nanometers d) micrometers e) centimeters

d) micrometers

39. Which of the following is a nucleotide? a) phosphate + ribose + deoxyribose b) nitrogenous base + deoxyribose c) phosphate + nitrogenous base d) nitrogenous base + ribose + phosphate

d) nitrogenous base + ribose + phosphate

20. In a cell, where are strong ionic bonds most likely to be found? a) in the cytoplasm b) between DNA strands c) deep in a protein's core where water is excluded d) on the surface of a protein e) on the surface of a lipid

d) on the surface of a protein

43. In a phospholipid, the end of the molecule likely to face towards a nonpolar environment is ________________. a) the end with the choline group b) the end with the phosphate group c) the region with the glycerol backbone d) the end with the fatty acid chains

d) the end with the fatty acid chains

15. Elements are likely to exhibit similar properties if: a) they have the same number of neutrons in their nuclei b) they have the same number of hybrid orbitals in their valence shell c) they have the same number of electrons in their innermost electron shell d) they have the same number of electrons in their valence electron shell

d) they have the same number of electrons in their valence electron shell

2. Which of the following statements accurately characterize cells? a) Cells are highly complex and organized. b) Cells possess a genetic program and the means to use it. c) Cells are capable of reproduction. d) Cells acquire and utilize energy via metabolism. e) All choices are correct.

e) All choices are correct.

4. What characteristics distinguish prokaryotic and eukaryotic cells? a) Eukaryotes have membrane-bound organelles; prokaryotes do not. b) Prokaryotes have relatively little DNA; eukaryotes generally have much more. c) Eukaryotic chromosomes are linear; prokaryotic chromosomes are circular. d) Eukaryotic DNA is usually heavily associated with protein to form a nucleoprotein complex called chromatin, which is not seen in prokaryotic genetic material. e) All of these are correct.

e) All of these are correct

5. Which of the following are NOT considered to belong to the Archaea? a) Methanogens b) Halophiles c) Acidophiles d) Thermophiles e) Eubacteria

e) Eubacteria

74. Which of the following is NOT a potential biological role of the lipid asymmetry of the plasma membrane? a) The glycolipids in the outer leaflet of the membrane may serve as receptors. b) The presence of phosphatidylinositol primarily in the inner leaflet is involved in signal transduction. c) The cell has the ability to maintain a charge differential in the two membrane leaflets. d) Appearance of phosphatidylserine on the outer surface of aging lymphocytes marks them for destruction by macrophages. e) Phosphatidylserine on the surface of platelets serves as a signal for blood solubilization.

e) Phosphatidylserine on the surface of platelets serves as a signal for blood solubilization.

80. Which protein(s) below is(are) thought to be involved in and influence the stability of red blood cell membranes and the cells themselves by imparting strength, elasticity, and pliability to the membrane? a) actin and tropomyosin b) spectrin c) band 3 d) ankyrin e) all of these are correct

e) all of these are correct

56. Which of the following is a function of membranes? a) compartmentalization b) creating a selectively permeable barrier c) mediating intercellular interactions d) helping cells respond to external stimuli e) all of these are correct choices

e) all of these are correct choices

19. Which of the groups participates exclusively in hydrophobic interactions? a) a b) b c) c d) d e) e

e) e

23. What kind of noncovalent interaction is typified by interactions between two molecules that are so close together that they can experience weak attractive forces bonding them together? a) hydrogen bond b) ionic bond c) hydrophobic interaction d) polar covalent bond e) van der Waals forces

e) van der Waals forces