Cell Biology Chapter 1-11 Quizzes

Which of the following could be considered a general function of all membrane-bound organelles? A. Organelles serve to compartmentalize specific cellular activities to provide more opportunity for regulation. B. Organelles provide specialized membranes for specialized functions. C. Organelles sequester cellular metabolites and enzymes to minimize the distances that they must diffuse to carry out their functions. D. All of the answer choices are general functions of all membrane-bound organelles.

D

Which of the following is NOT a function of the TCA cycle? A. The TCA cycle serves to provide precursors for anabolic pathways. B. The TCA cycle serves to provide a majority of reduced coenzymes to the electron transport system. C. The TCA cycle serves to produce a small amount of GTP/ATP. D. All of the other answer choices are functions of the TCA cycle.

D

Which of the following is a reasonable thermodynamic and mechanistic description of how cells may perform mechanical work? A. Cells use carbohydrates as energy-converting machines to convert the chemical energy of lipids into mechanical energy. B. Cells use nucleic acids and nucleotides as energy-converting machines to convert the chemical energy of proteins into mechanical energy. C. Cells use lipids as energy-converting machines to convert the chemical energy of nucleic acids and nucleotides into mechanical energy. D. Cells use proteins as energy-converting machines to convert the chemical energy of nucleic acids and nucleotides into mechanical energy.

D

Which of the following organelles is not generally found in animal cells? A. food vacuole B. centriole C. mitochondrion D. central vacuole E. endoplasmic reticulum

D

Which of the following properties is characteristic of water? A. high specific heat B. High surface tension C. high heat of vaporization D. All of the other answer choices are properties that are characteristic of water.

D

Which of the following should be considered when a pharmaceutical company is trying to design a drug that will act as a competitive inhibitor of an enzyme critical for the survival of a pathogenic bacterium? A. The charge distribution on the drug should be similar to the charge distribution on the natural substrate of the enzyme you are trying to inhibit. B. The drug should not inhibit a host (human enzyme) but should inhibit an enzyme critical for the survival of the pathogen. C. The stereochemistry of the drug should mimic the stereochemistry of the natural substrate of the enzyme you are trying to inhibit. D. All of the other answer choices should be considered when a pharmaceutical company is trying to design a drug that will act as a competitive inhibitor of an enzyme critical for the survival of a pathogenic bacterium.

D

Which of the following statements is true comparing the simple diffusion of a substance across a membrane to the facilitated/active movement of a substance across a membrane? A. All movement (simple diffusion and facilitated/active transport) of solute across a membrane requires a membrane protein, but only facilitated/active transport exhibits saturable behavior and is subject to competitive inhibition. B. Active transport is subject to competitive inhibition, and simple diffusion and facilitated/active transport require a membrane protein and exhibit saturable behavior. C. All movement (simple diffusion and facilitated/active transport) of solute across a membrane requires a membrane protein but only simple diffusion exhibits saturable behavior and is subject to competitive inhibition. D. Simple diffusion differs from facilitated diffusion and active transport in that it is not dependent on a membrane protein, does not exhibit saturation kinetics, and is not subject to competitive inhibition.

D

_________ fatty acids have __________ and contribute to increased membrane fluidity. A. Unsaturated; no double bonds B. Saturated; double bonds C. Saturated; no double bonds D. Unsaturated; double bonds

D

Which of the following most accurately summarizes the total contribution of the biochemical strand to modern cell biology? A. Biochemical techniques allow for the isolation and characterization of the structure and function of cellular components, and how these cellular components work together to contribute to the biology of the cell. B. Biochemical techniques have demonstrated that most cellular chemistry cannot be replicated in cell-free systems. C. Biochemical techniques allow for the visualization of cellular structures within the context of genetic inheritance. D. Biochemical techniques have demonstrated that ATP is the principal energy storage compound in most cells.

A

__________ facilitate the assembly of proteins but are NOT components of the protein or protein-containing structure. A. Chaperones B. Polypeptides C. Fatty acids D. Steroids

A

Which of the following is LEAST likely to contribute to enzyme-substrate specificity? A. The size of the enzyme is appropriate for the reaction. B. The charge on a substrate is opposite to the charge of one or more residues in the active site. C. The size of the substrate should be comparable in size to the enzyme active site. D. The shape of the substrate is complementary to the shape of the active site.

A

Which of the following is NOT a type of transport ATPase? A. S-type B. ABC-type C. P-type D. V-type

A

Which of the following is closest to a nanometer in size? A. the width of a strand of DNA B. the length of a chicken egg C. a typical prokaryotic cell D. the size of a mitochondrion E. the length of a plant cell

A

Which of the following is smallest? A. protein B. ribosome C. virus D. prokaryote E. mitochondrion

A

Because the citric acid cycle links degradation and synthesis, the pathway is classified as A. anabolic. B. amphibolic. C. catabolic. D. bipolar. E. amphipathic.

B

Cellulose belongs to which of the following groups of macromolecules? A. lipids B. carbohydrates C. proteins D. nucleic acids E. none of these

B

Consider the following list of phosphorylated compounds with their free energies of phosphate hydrolysis: Glucose-1-phosphate: -5.0 kcal/mol PEP: -14.8 kcal/mole ATP: -7.3 kcal/mol Which of these molecules could phosphorylate an unknown compound whose free energy of phosphate hydrolysis is -10.3kcal/mol? A. Glucose-1-phosphate only B. PEP only C. ATP only D. ATP and PEP E. All three could phosphorylate the unknown compound.

B

In bacteria, the TCA cycle takes place in the __________. A. plasma membrane B. cytoplasm C. mitochondrial matrix D. intermembrane space of the mitochondria

B

In which of the following properties are the archaea more like eukaryotes than the bacteria? A. size B. translation initiation C. microtubules and microfilaments D. mode of cell division E. both translation initiation and mode of cell division

B

The enzyme pyruvate dehydrogenase is an allosteric enzyme that binds to, and is regulated by, a variety of allosteric effectors (both inhibitors and activators). Which of the following is likely characteristic of pyruvate dehydrogenase? A. The active conformation of pyruvate dehydrogenase likely has a higher affinity for substrates than does the inactive conformation. B. Pyruvate dehydrogenase has at least two conformations, an active form and an inactive form. C. Pyruvate dehydrogenase is a large, multisubunit protein. D. All of the other answer choices are likely characteristics of pyruvate dehydrogenase.

D

The major structural elements of the cytoskeleton are A. proteoglycans and cellulose microfibrils. B. the extracellular matrix and the cell wall. C. the cytoplasm and cytosol. D. microtubules, microfilaments, and intermediate filaments. E. cleavage furrows and G-actin.

D

The minimum energy that two molecules must have before a successful reaction will take place is defined as __________. This quantity influences the __________ of the reaction. A. enzyme catalysis; enthalpy B. potential energy; temperature C. free energy; spontaneity D. activation energy; kinetics

D

Transmembrane segments of membrane proteins can contribute to all of the following functions EXCEPT __________. A. serving in signal transduction across membranes B. facilitating exocytosis C. transporting solutes from outside to inside the cell D. serving as targets for glycosylation

D

Viruses are important in the study of cell biology because A. they are the simplest form of cellular life. B. they cause disease. C. they are the simplest form of cellular life and are used as model organisms to study molecular biology and genetics. D. they cause disease and are used as model organisms to study molecular biology and genetics. E. they are used as model organisms to study molecular biology and genetics.

D

A scientist working at an herbarium suspects that her plants are infected by an acellular pathogen. Which of the following data would indicate that the plants were infected by a viroid and not a virus or prion? A. Isolation of the pathogen reveals that it is composed of both protein and nucleic acids. B. Isolation of the pathogen reveals that it is composed of only carbohydrates. C. Isolation of the pathogen reveals that it is composed of only small, circular RNA. D. Isolation of the pathogen reveals that it is composed of only protein.

C

Bioenergetics can be simply defined as A. holding constant the variables in the universe. B. the application of biological principles to physics. C. applied thermodynamics. D. the units in which energy is expressed. E. a subdivision of biology.

C

Cholesterol A. All of the above are correct. B. increases permeability for Ca2+. C. buffers membrane fluidity by increasing fluidity at low temperature and decreasing fluidity at high temperature. D. increases permeability for small polar molecules. E. is found in abundance in prokaryotic cell membranes.

C

Cystic fibrosis is caused by a defective __________. A. aquaporin B. sodium pump C. chloride ion channel D. multidrug resistance transporter

C

Early microscopes did not allow clear visualization of cells because they were limited by A. number of kernels. B. refraction. C. both magnification and resolution. D. magnification only. E. resolution only.

C

In a mammalian cell (such as a human erythrocyte), a common form of membrane transport would be __________. A. oxygen entering the cell via active transport B. carbon dioxide entering the cell via osmosis C. glucose entering the cell via facilitated diffusion D. Na+ leaving the cell via an anion exchange protein

C

Organisms that use ferric ions and elemental sulfur as terminal electron acceptors are undergoing __________. A. fermentation B. aerobic respiration C. anaerobic respiration D. substrate-level phosphorylation

C

Oxidation reactions in biological systems generally involve A. loss of electrons and addition of hydrogen ions. B. addition of electrons and hydrogen ions. C. loss of electrons and hydrogen ions. D. loss of electrons and either addition or loss of hydrogen ions. E. addition of electrons and loss of hydrogen ions.

C

The enzyme hexokinase has been crystallized in the presence and absence of substrate and been shown to have two different conformations depending on whether the substrate is bound in the active site or not. Which of the following theories and models is supported by this observation? A. the lock-and-key model of enzyme-substrate binding B. the first law of thermodynamics C. the induced-fit model of enzyme-substrate binding D. the Michaelis-Menten kinetic theory

C

Which descriptor of polymers is INCORRECT? A. composed of monomers B. polymerization reactions are condensation reactions C. do not display directionality in their structure D. generally the polymers are formed inside the cell rather than being transported into the cell

C

Which field of cell biology is primarily concerned with cellular structure? A. proteomics B. biochemistry C. cytology D. genetics

C

Which of the following explains why multiple electron transport complexes are used to oxidize NADH rather than allowing NADH to reduce O2 in a single step? A. Lactic acid would build up with a single oxidation. B. The TCA cycle would be inhibited. C. The oxidation of NADH to reduce O2 in a single step would release an enormous amount of energy at once, most of which would likely be lost as heat. A single step oxidation would be extremely complicated. D. NADH oxidation would be endergonic in a single step.

C

Which of the following is defined as "heat content"? A. solar radiation B. entropy C. enthalpy D. heat loss E. energy output

C

Which of the following is least likely to be part of a cell membrane? A. enzymes B. glycoproteins C. peptidoglycans D. transport proteins E. phospholipids

C

Which of the following is the logical conclusion of the discovery of ribozymes? A. Ribozymes confirm the existence of DNA. B. The existence of ribozymes suggests that evolution is moving toward RNA catalysts rather than protein catalysts. C. Ribozymes are likely the first example of a biological catalyst in evolution and may have served as a template for the evolution of protein-based catalysts. D. Ribozymes violate the first law of thermodynamics.

C

Which of the following accurately describes the structure of fibrous proteins? A. Fibrous proteins usually contain a number of different domains with different structural motifs. B. Fibrous proteins are composed of an equal mixture of α helices and β sheets with interconnecting looped segments. C. Fibrous proteins have a simple primary structure and very little secondary structure, resulting in long, thin fibers. D. Fibrous proteins are usually composed of either α helices or β sheets throughout the molecule, giving them a highly ordered, repetitive structure. E. Fibrous proteins have an extensive tertiary and quaternary structure that affects the strength and elasticity of each fiber.

D

In aerobic cellular respiration, __________ is oxidized and __________ is reduced. Protons are __________ pumped from the mitochondrial __________ to the mitochondrial __________. A. ATP; oxygen; actively; matrix; cytoplasm B. carbon dioxide; water; passively; inner membrane space; matrix C. oxygen; ATP; passively; inner membrane space; matrix D. pyruvate; oxygen; actively; matrix; inner membrane space

D

The FoF1 complex of the ATP synthase__________. A. is found on the mitochondrial inner membrane B. serves as a proton translocator C. is composed of multiple polypeptide subunits D. All of the listed responses are correct.

D

The complete folding of polypeptides into proteins can be attributed to which of the following? A. hydrogen bonds B. electrostatic interactions C. hydrophobic effects D. All of the other answer choices identify forces that can affect the folding pattern of proteins.

D

Which of the following compounds would NOT alter the behavior of a plasma membrane voltage-gated channel? A. a chloride ionophore (drug) that facilitates the Cl− gradient to go to equilibrium across the plasma membrane B. a calcium ionophore (drug) that facilitates the Ca2+ gradient to go to equilibrium across the plasma membrane C. a potassium ionophore (drug) that facilitates the K+ gradient to go to equilibrium across the plasma membrane D. a drug that inhibits GLUT1 (the glucose transporter)

D

Which of the following has the greatest number of glycosidic bonds? A. amylose B. vitamin A C. triacylglycerol D. DNA E. glucose

A

An enzyme A. binds substrates in a manner that facilitates the formation of product. B. changes the position of the equilibrium of the reaction. C. does not change the rate at which the equilibrium is achieved. D. is always a protein and decreases the rate of a reaction.

A

Bacteriorhodopsin is a transmembrane protein that uses light energy to __________. A. create a proton gradient B. bind to retinol C. hydrolyze ATP D. activate a Na+ pump

A

Complementary relationships between purines and pyrimidines A. allow adenine to form two hydrogen bonds with thymine (or uracil) and guanine to form three hydrogen bonds with cytosine to form double-stranded nucleic acids. B. allow the interaction of the oppositely charged amino acids to form the tertiary structure of proteins. C. allow adjacent bases in a nucleotide chain to stack tightly, stabilizing the DNA double helix. D. provide highly ordered, repetitive bonding to form α helices and β sheets within proteins. E. Both A and C are correct.

A

During the conversion of 1,3-bisphosphoglycerate to 3-phosphoglycerate and phosphoenolpyruvate, a phosphate group is added to ATP to generate ATP. The mechanism for ATP production in this reaction is A. substrate-level phosphorylation. B. product-level phosphorylation. C. anabolic phosphorylation. D. oxidative phosphorylation. E. aerobic phosphorylation.

A

In a chemical reaction, the standard free energy change (ΔG°') is calculated to be 3.67 cal/mol. What can be said of the chemical reaction? A. The reaction is not spontaneous under standard conditions. B. The reaction is at equilibrium under standard conditions. C. There can be no reaction. D. Products predominate over reactants at equilibrium under standard conditions. E. The reaction goes spontaneously to the right under standard conditions.

A

Oil droplet in water coalesce to form a separate phase because of the strong attraction of hydrophobic molecules for each other. A. FALSE B. TRUE

A

Succinylcholine is structurally similar to acetylcholine. If succinylcholine combines with the enzyme that normally hydrolyzes acetylcholine, the enzyme is no longer able to hydrolyze acetylcholine. This suggests that __________. Bloom's Taxonomy: Application/Analysis A. succinylcholine must be a competitive inhibitor with acetylcholine B. succinylcholine must be an allosteric regulator for this enzyme C. the activation energy barrier for succinylcholine hydrolysis is higher than that for acetylcholine hydrolysis D. succinylcholine must be a noncompetitive inhibitor

A

The Na+-glucose symporter serves to move one molecule of glucose into the cell and 2 Na+ into the cell despite the concentration of glucose being almost equal inside the cell and outside the cell. Which of the following must be true? A. Glucose transport kinetics mediated by the Na+-glucose symporter is saturable and can likely be inhibited by a glucose analog. B. The kinetics of the Na+-glucose symporter are linear. C. The Na+-glucose symporter can transport glucose into the cell independently of the Na+ and K+ gradient established by the Na+/K+ pump. D. The Na+-glucose symporter is assisting the Na+/K+ pump in maintaining the resting membrane potential at approximately -70 mV.

A

The chemical nature of each amino acid is determined by which of the following groups? A. R B. hydroxyl C. amino D. hydrogen E. carboxyl

A

The enzyme prolyl hydroxylase can be isolated from human tissues in both an active and inactive form. The active form of prolyl hydroxylase contains a molecule of ascorbic acid in the active site, whereas the inactive form of the enzyme lacks ascorbic acid. Which of the following must be true? A. Ascorbic acid is a prosthetic group for prolyl hydroxylase. B. Ascorbic acid is an allosteric inactivator. C. Ascorbic acid is a competitive inhibitor. D. Ascorbic acid is a protein.

A

The gross output of ATP from glycolysis is ________, whereas the net output of ATP is ________. A. 4; 2 B. 6; 4 C. 4; 1 D. 2; 4 E. 2; 1

A

The rate of simple diffusion of a polar molecule across a membrane is directly and linearly proportional to __________. The thickness of a membrane is expected to be __________ to the rate of simple diffusion for polar molecules. A. its concentration difference across the membrane; inversely proportional B. its molecular weight; directly proportional C. its net charge; inversely proportional D. its concentration within the cell; directly proportional

A

Which answer correctly shows the hierarchical nature of cellular structure from the simplest to the most complex? A. organic molecules, macromolecules, organelles, a cell B. a cell, macromolecules, organic molecules, organelles C. macromolecules, organic molecules, a cell, organelles D. organic molecules, macromolecules, a cell, organelles

A

Which of the following accurately explains why cells and organisms must be open thermodynamic systems? A. Cells and organisms must be open thermodynamic systems to exchange matter and energy with the surroundings in order to stay away from thermodynamic equilibrium. B. Cells and organisms must be open thermodynamic systems in order to allow us to measure changes in enthalpy, entropy, and free energy. C. Cells and organisms must be open thermodynamic systems so that they may dispose of unwanted heat. D. Cells and organisms must be open thermodynamic systems in order to violate the second law of thermodynamics.

A

Which of the following could be an appropriate diagnostic to determine if an unknown cell is prokaryotic rather than eukaryotic? A. the presence of hopanoids B. the presence of glycoproteins C. the presence of a cell wall D. the presence of phospholipids

A

Membrane phospholipids are asymmetrically oriented in phospholipid bilayers as a result of the ease or restriction of mobility with respect to the plane of the membrane. Which of the following is NOT a correct thermodynamic interpretation of the phospholipid bilayer structure and asymmetry? A. Phospholipids generally can rapidly rotate about their long axis to help increase the entropy of the system. B. Phospholipids can rapidly flip-flop from one leaflet or monolayer of a bilayer to another to decrease the enthalpy of the system. C. Phospholipids can rapidly exchange places with lateral, neighboring phospholipids within the same leaflet of the bilayer to help increase the entropy of the system. D. Phospholipid polar head groups face outward to contact the aqueous environment to help decrease the enthalpy (negative ΔH) of the membrane-solvent system.

B

Membrane potential is __________. For a cell with a negative membrane potential, the movement of anions from outside to inside the cell is expected to be __________, whereas the movement of cations from outside to inside the cell is expected to be __________. The combination of the membrane potential and concentration differences for particular ions across the membrane is known as the __________ for that ion. A. the concentration of solutes inside versus outside a cell; less difficult; at equilibrium; chemical potential B. the difference in net charge on opposite sides of a membrane; more difficult; less difficult; electrochemical potential C. defined as the electrochemical potential; less difficult; more difficult; membrane potential D. the likelihood that molecules can cross a membrane; less difficult; more difficult; molar concentration

B

Membranes from cells grown in media enriched with stearate are less fluid than normal membranes. This is because __________. A. the membranes probably have less sterols B. the membranes have more saturated fatty acids C. the membranes have more unsaturated fatty acids D. the membranes have a lower transition temperature

B

Of the following cell structures, which is the only one that can be seen using a light microscope? A. membranes B. the nucleus C. microtubules D. the DNA double helix

B

The Keq for transport of an uncharged solute moving into a cell by diffusion is __________. A. equal to zero B. greater than 1 C. equal to 1 D. less than 1

B

The carbon atom is tetravalent. This means that __________. A. carbon readily forms ionic bonds B. a carbon atom can complete its valence shell by forming four covalent bonds C. the bond angle between each bond is 90°, forming an arrangement like the points on a compass D. carbon cannot form stereoisomers

B

The classic work of Friedrich Wöhler (1828) that united the fields of biology and chemistry was based on the A. identification of nucleotide bases. B. production of urea in the laboratory. C. discovery of ATP. D. analysis of gene segregation. E. discovery of yeast ferments.

B

The smooth endoplasmic reticulum functions in synthesis of A. polysaccharides. B. lipids. C. DNA. D. lipids, polysaccharides, proteins, and DNA. E. proteins.

B

The steps of the scientific method, in the correct order, are A. collect data, interpret results, test the hypothesis, make observations, and design experiments. B. make observations, formulate the hypothesis, design experiments, collect data, interpret results, and draw conclusions. C. design experiments, draw conclusions, collect data, interpret results, make observations, and test the hypothesis. D. none of the above. E. collect data, interpret results, test the hypothesis, design experiments, make observations, and draw conclusions.

B

Water is an excellent solvent for __________. A. lipids B. sugars C. the side chains of all amino acids D. hydrocarbons

B

Which answer is a fundamental concept of the cell theory? A. Cells arise spontaneously from organic matter. B. All animals are made of cells. C. All organisms are made of many cells. D. Viruses exist independently of cells.

B

Which of the following is NOT an example of a thermodynamically spontaneous process? A. paper burning B. synthesis of sugar C. ice cubes melting in a glass at room temperature D. sugar dissolving in pure water

B

Which of the following is NOT true concerning eukaryotic plasma membranes? A. Eukaryotic plasma membranes may contain C, H, O, N, S, and P atoms. B. Eukaryotic plasma membranes can be of unlimited size. C. The eukaryotic plasma membrane will often have oligosaccharides facing the extracellular environment. D. The eukaryotic plasma membrane can be described as a selectively permeable barrier.

B

Which of the following is false? A. Phospholipids are important in membrane structure. B. Sphingolipids are the predominant phospholipid in membranes. C. Serine is a molecule that may be part of a phosphoglyceride. D. Phospholipids are amphipathic E. Phosphatidic acid contains two fatty acids and a phosphate group.

B

Which of the following statements best describes the role of NAD+/NADH in glycolysis? A. NADH is used to directly create the phosphoanhydride bonds in ATP. B. NAD+ accepts electrons. C. NADH accepts electrons during fermentation. D. NADH is used primarily in substrate-level phosphorylation. E. All of the above are correct.

B

Which property of water is true but is LEAST important for making water a desirable component of cells? A. water is a polar molecule and hence an excellent solvent for polar compounds B. water is odorless and tasteless C. water has a high heat of vaporization D. water has a high specific heat

B

Which type of microscopy has the greatest resolving power? A. confocal scanning microscopy B. electron microscopy C. digital video microscopy D. fluorescence microscopy E. phase-contrast microscopy

B

You are researching a cytoplasmic protein associated with a nerve disorder. The native form of the enzyme appears to be globular protein; however, when a sample of the purified protein is treated with a chemical that reduces disulfide bonds, the enzymatic activity decreases dramatically and multiple globular proteins can be detected in the sample. What does this tell you about the protein? A. The protein is most likely composed of α helices that are held together by disulfide bonds. B. The protein is most likely composed of multiple polypeptide chains that are held together by disulfide bonds. C. The primary and secondary structure of the protein depends on disulfide bonds. D. The protein is most likely composed of β sheets that are held together by disulfide bonds. E. The primary structure of the protein contains multiple cysteine residues that are hydrolyzed by the chemical reductant.

B

β-oxidation A. is the second step in the oxidation of glucose. B. is a process used to oxidize fatty acids. C. occurs in the cytoplasm. D. is a process used to digest some polysaccharides. E. lengthens fatty acids by addition of two carbons.

B

Which of the following is the most accurate description of an animal cell membrane? A. An animal cell membrane is a selectively permeable membrane that is composed of a bilayer of amphipathic phospholipids and glycolipids that are interspersed with cellulose and membrane proteins, which can serve as transporters, enzymes, and receptors. B. An animal cell membrane is a selectively permeable membrane that is composed of a bilayer of hydrophobic phospholipids and glycolipids that are interspersed with sterols and membrane proteins, which can serve as transporters, enzymes, and receptors. C. An animal cell membrane is a selectively permeable membrane that is composed of a bilayer of amphipathic phospholipids and glycolipids that are interspersed with sterols and membrane proteins, which can serve as transporters, enzymes, and receptors. D. An animal cell membrane is an impermeable membrane that is composed of a bilayer of amphipathic phospholipids and glycolipids that are interspersed with sterols and membrane proteins, which can serve as transporters, enzymes, and receptors.

C

You discover an integral membrane protein that has terminal sialic acid groups attached to amino acid residues via N- and O-links. It is, therefore, most likely __________. A. a lipoprotein B. a carbohydrate C. a glycoprotein D. a structural protein

C

__________ binds to an enzyme covalently, causing a loss of catalytic activity. A. A product B. A competitive inhibitor C. An irreversible inhibitor D. A substrate

C

In a reversible chemical reaction at equilibrium, the concentration of X (the reactant) is 0.75 mol/L, and the concentration of Y (the product) is 2.25 mol/L. At 25°C, what would be the Keq? A. 37.5 B. 0.33 C. 1.50 D. 3.0 E. 1.69

D

A cellular biologist exposes both sides of a membrane to a fluorescent chemical that nonspecifically labels proteins exposed to the aqueous solvent but not portions of those proteins exposed to the interior of the membrane environment. Which of the following classes of proteins would NOT be labeled on both sides of the membrane? A. multisubunit proteins that are extractable only by using detergent B. multipass C. singlepass D. integral monotopic

D

Cells need energy for which of the following purposes? A. mechanical work B. electrical work C. biosynthesis D. All the listed purposes require energy.

D

Consider the definition of energy and how energy and mass interact in the biosphere, and determine which of the following scenarios would violate the first law of thermodynamics. A. People who exercise must consume more calories to maintain the same body weight. B. A pregnant female must consume more food to support the development of the fetus. C. Plant cells convert the energy of light to fix carbon in the form of carbohydrates. D. A cell accumulates 10 kcal worth of energy in order to generate 15 kcal worth of bioluminescent work. E. The molecular motor, myosin, hydrolyzes ATP to move along a microtubule in a liver cell.

D

Each of the following is a product of the citric acid cycle except A. CO2. B. ATP. C. NADH. D. acetyl CoA. E. FADH2.

D

Fatty acids are ________; they function in the cell as ________. A. four-ringed hydrocarbon molecules; key components of membranes B. short chains of double-bonded carbon molecules; vitamins, cofactors, and storage lipids C. short chains of double-bonded carbon molecules; vitamins and cofactors D. long, unbranched hydrocarbon chains with a carboxyl group at one end; building blocks for other lipids E. short chains of double-bonded carbon molecules; storage lipids

D

A negative free energy change indicates that A. the reaction is not possible. B. the reactant is predominant at equilibrium. C. energy must be added to the reaction before it can proceed. D. the reaction is at equilibrium. E. the reaction is exothermic.

E

A phosphoanhydride bond A. is a high-energy bond. B. has a standard free energy of hydrolysis of −7.3 kcal/mol. C. is broken by hydrolysis. D. links two phosphate groups. E. All of the above are correct.

E

Each of the following can be the final electron acceptor in bacterial aerobic or anaerobic respiration except A. Fe3+. B. hydrogen ions. C. oxygen. D. sulfur. E. pyruvate.

E

Each of the following is true about homeoviscous adaptation in membranes EXCEPT A. may increase the unsaturation of membrane lipid fatty acid tails. B. maintains membrane viscosity despite changes in environmental temperature. C. may decrease the average length of membrane lipid fatty acid tails. D. may increase the proportion of cholesterol in animal cell membranes. E. occurs primarily in homeothermic (warm-blooded) organisms and only rarely in poikilothermic (cold-blooded) organisms.

E

Experiments by Stanley Miller in the 1950s demonstrated that the first organic molecules on earth A. were nucleic acids such as RNA and DNA. B. were catalysts composed of simple amino acids. C. were catalysts composed of simple amino acids and most likely formed in an extraterrestrial environment and were deposited on earth via asteroids. D. most likely formed in an extraterrestrial environment and were deposited on earth via asteroids. E. could have formed abiotically in a reducing atmosphere containing hydrogen, methane, ammonia, and water vapor.

E

In animal cells, glycolysis and gluconeogenesis are regulated to ensure that both processes are reciprocally active. This regulation involves each of the following compounds except A. acetyl CoA. B. fructose-2,6-bisphosphate. C. AMP. D. cAMP. E. NADH.

E

In eukaryotes, pyruvate is converted to acetyl CoA A. in the cellular cytosol. B. during passage through the mitochondrial outer membrane. C. in the intermembrane space. D. during passage through the inner mitochondrial membrane. E. in the mitochondrial matrix.

E

The composition of lipids in the outer and inner monolayers of cell membrane lipid bilayers is A. the same for all cell plasma membranes but different from the composition in mitochondrial and chloroplast membranes. B. identical in each monolayer. C. highly random for each monolayer. D. twice as concentrated in the inner monolayer as in the outer monolayer. E. asymmetrical; i.e., different in each monolayer.

E

The process of gluconeogenesis converts pyruvate or lactate into A. sucrose. B. mannose. C. fructose. D. gluconate. E. glucose.

E

The two strands of DNA are held together by ________; thus ________. A. covalent bonds; double-stranded DNA is very stable at a range of temperatures B. ionic bonds; double-stranded DNA separates into two separate strands in water C. antiparallel bonds; double-stranded DNA is amphipathic D. hydrophobic interactions; double-stranded DNA separates into two separate strands when dissolved in a hydrocarbon (hydrophobic) solvent E. hydrogen bonds; double-stranded DNA separates into two separate strands at high temperatures

E

Two proteins associated with a rare neurodegenerative disorder have been sequenced. Protein A contains many polar amino acids with small regions containing nonpolar, hydrophobic amino acids. Protein B is rich in nonpolar, hydrophobic amino acids with only two small regions containing polar amino acids. What might this suggest about the two proteins? A. Protein A is fibrous and Protein B is globular. B. The two proteins may have different quaternary structures. C. Protein A is most likely an enzyme and Protein B is most likely a storage protein. D. Protein A and Protein B are complementary parts of a supramolecular structure. E. Protein A may be a cytoplasmic protein and Protein B may be a membrane associate protein.

E

Which of the following is a coenzyme? A. NAD B. NADP C. FAD D. CoA E. All are coenzymes

E