MCB Exam Questions fully solved and updated

When we say that the cell is the fundamental unit of life, we meant that: A. All living things are made up of one or more cells. B. The smallest entity that can be considered living is a cell. C. A single cell can carry out all life processes. D. Life doesn't exist in the absence of cells. E. All of the answer options are correct. - answer-E The ability of an atom to react and form bonds with another atom is determined directly by: A. The atomic number of the atom. B. The row of the periodic table in which the element is found C. The number and distribution of electrons in the atom, and whether its outer shell is full D. The number of neutrons in the nucleus in relation to the number of electrons E.The mass of the atom - answer-C A major difference between prokaryotic cells and eukaryotic cells is that ________ A. Eukaryotic cells contain membrane-bound organelles and prokaryotic cells do not B. Eukaryotic cells have a nucleus and prokaryotic cells do not C. Prokaryotic cells have circular chromosomes and eurkaryotic cells have linear chromosomes D. Eukaryotic cells are bigger than prokaryotic cells E. All of these are major differences between prokaryotic and eukaryotic cells - answer-E The central dogma of molecule biology states that information flows from A. DNA directly to proteins B. Protein to RNA to DNA C. RNA to DNA to protein D. RNA to protein to DNA E. DNA to RNA to protein - answer-E Which one of the following elements would mostly likely have the same number of electrons in its outer shell as nitrogen (N)? A. Silicon (Si) B. Helium (He) C. Carbon (C) D. Phosphorus (P) E. Potassium (K) - answer-D Refer to the periodic table, and decide which of the following molecules is held together by ionic bonds. A. NH3 B. CO2 C. CH4 D. H2O E. KCl - answer-E Transcription is the process by which: A. RNA is synthesized from protein. B. RNA is synthesized from DNA. C. Proteins are synthesized from DNA molecules. D. DNA is synthesized from protein. E. Proteins are synthesized from RNA molecules. - answer-B Which one of the following statements about viruses is incorrect? A. Most viruses use a host's energy and cellular machinery to replicate their genetic material. B. The hereditary molecule in viruses is composed of nucleic acids. C. Viruses do not possess the ability to harness energy from the environment. D. Viruses are considered living cells. E. All of the above statements are correct. - answer-D Which one of the following amino acids has its R group covalently linked to the amino group? A. Glycine B. Serine C. Cysteine D. Glutamic acid E. Proline - answer-E Which one of the following is not a component of a nucleosome core particle? A. Histone H4 B. Approximately 150 base pairs of DNA C. Histone H2B D. Histone H5 E. All are part of a nucleosome - answer-D The two types of secondary structure interactions are referred to as: A. Primary and secondary B. Amide and carbonyl C. Residual and permanent D. Sulfhydryl and phosphatidic E. Alpha helix and beta sheet - answer-E Which one of the following is found in a nucleoside triphosphate? A. One or more phosphate groups B. A sugar C. A fatty-acid D. Both A and B E. Both A and C - answer-D Three carbon atoms are linked by single covalent bonds such that they form the shape of a V. All of the unshared electrons form covalent bonds with hydrogen. How many hydrogen atoms does this molecule contain? A. 2 B. 4 C. 4 D. 8 E. 10 - answer-D Several chemical properties make water uniquely suited for its role as a central "molecule of life." Which of the following is true? A. Covalent bonding between adjacent water molecules. B. Water is a poor solvent of molecules within ionic bonds such as NaCl. C. Water is always non-polar D. The structure of a water molecule is destabilized by hydrogen bonds E. The oxygen in water has a slight negative charge - answer-E Many hydrophilic molecules interact freely with water, but there are a number of hydrophobic molecules important for life, too. How does the interaction between water and hydrophobic molecules help to organize biological systems? A. Because water molecules preferentially associate with one another, they force hydrophobic molecules to associate with one another and not with water molecules. B. Because cells are not pure water (they have many substances dissolved within them), the hydrophilic/hydrophobic effect has little role in biological organization C. The covalent bonds between water molecules cause hydrophobic molecules to associate with one another and not with water molecules. D. All of the above E. None of the above - answer-A Biological polymers are A. Strings of repeated units (called monomers) linked together by covalent bonds B. Assembled from monomer units that are exactly identical to one another C. Assembled by enzymes that catalyze a hydrolysis reaction, in which a water is added as the monomers are linked D. Assembled by enzymes that catalyze a condensation reaction, in which a carbon dioxide is liberated as new monomers are added. E. Molecules that spontaneously form in cells without an input of energy - answer-A Which of the following represents an actual Watson-Crick base pair with the most number of hydrogen bonds? A. Uracil and adenine B. Adenine and thymine C. Thymine and guanine D. Cytosine and thymine E. Cytosine and guanine - answer-E Which of the following is not true of DNA? A. RNA polymerase uses it to transcribe RNA B. A phosphate group in a nucleotide is attached to the 5' carbon in deoxyribose C. A purine always forms a complementary base pair with a pyrimidine D. The percentage of the purine A always equals the percentage of the pyrimidine T E. The nucleotides in one strand are connected by hydrogen bonds - answer-E The strands in a DNA molecule are A. Covalently bonded to each other B. Complementary C. Antiparallel D. Both B and C E. A, B, and C - answer-D In the DNA sequence 5'-TGAC-3', the phosphodiester linkage between the guanine and the adenine connects A. The 3' end of the guanine to the 5' end of the adenine B. The 2' end of the adenine to the 3' end of the guanine C. The 5' end of the guanine to the 3' end of the adenine D. The 3' end of the adenine to the 3' end of the guanine E. The 5' end of the guanine to the 5' end of the adenine - answer-A Variation among individuals in a species is usually caused by: A. Environmental variation B. Genetic variation C. Infectious variation D. Both environmental and genetic variation E. Environmental, genetic, and infectious variation - answer-D In a phylogenetic tree, nodes in the tree are: A. Currently living species B. Currently living relatives of species at the tips C. Extinct ancestors of species at the tips D. Both A and C E. Not of significance - answer-C In science, the terms "fact" and "theory" are used somewhat differently from the way they are used in conversational English. These differences include which of the following? A. In science, a fact and theory are the same thing. B. In science, a theory is a large body of observations and experiments while a fact is based on a single observation. C. In science, a theory is a semi-educated guess. D. In everyday English, theories are stronger than facts. E. In science, one a theory is proven, it becomes a fact. - answer-B Which of the following correctly reflects the process of science? A. Observation, hypothesis formulation, question, experiment, prediction B. Observation, question, hypothesis formulation, experiment, support or refute hypothesis C. Observation, question, hypothesis formulation, experience, prove or disprove hypothesis D. Observation, question, experiment, hypothesis formulation, prove or disprove hypothesis E. Observation, question, experiment, hypothesis formulation, support or refute hypothesis - answer-B Non-virulent bacteria can be prevented from being transformed into virulent bacteria if the debris from heat-killed virulent bacteria is first treated with: A. RNase B. Protease C. DNase D. Polymerase E. Both A and C - answer-C Which of the following most accurately describes a non-polar covalent bond? A. The interaction of a hydrogen connected to an atom with a high electronegativity, and an electronegative atom of another molecule B. The interaction of an atom with very high electronegativity and an atom with very low electronegativity C. The equal sharing of electrons between an atom with a partial positive charge and an atom with a partial negative charge D. The unequal sharing of electrons between atoms of identical or similar electronegativities E. None of these choices accurately describe polar covalent bonds. - answer-E During elongation of translation, the growing polypeptide is transfered from the tRNA in the ____ site of the ribosome to the tRNA in the ____ site as a peptide bond is formed between the growing polypeptide to the newest tRNA. A. A; P B. A; E C. P; A D. P; E E. E; A - answer-C Which of the following types of post-transcriptional modification is(are) common in eukaryotes? A. Polyadenylation B. Intron removal C. 5' cap addition D. All of the choices are correct E. None of the choices are correct, eukaryotes don't process transcripts - answer-D An unsaturated fatty acids contains A. Only carbon and hydrogen B. Only single covalent bonds between carbon atoms C. One or more double bonds between carbon atoms D. One or more double bonds between hydrogen atoms E. Both double bonds between carbon atoms and double bonds between carbon and hydrogen atoms are required for a fatty acid to be considered unsaturated - answer-C Which one of the following would be most likely to diffuse across a lipid bilayer? A. K+ B. DNA C. N2 D. Na+ E. Proteins - answer-C Which of the following types of fatty acids would be most likely to participate in the HIGHEST number of van der Waals forces with other fatty acids? Fatty acids with: A. Long tails and low saturation B. Long tails and high saturation C. Short tails and low saturation D. Short tails and high saturation - answer-B Which property of phospholipids allows membrane proteins involved in the same biochemical pathway to associate with each other? A. Formation of lipid rafts B. Amphipathic nature of the phospholipids C. Flip-flop of individual phospholipids D. Decreased fluidity of the membrane due to carbon-carbon double bonds - answer-A Which one of the following steps in translation is not part of the elongation phase? A. Movement of the ribosome three bases closer to the 3' end of the mRNA B. Ejection of an uncharged tRNA fro mthe E site of the ribosome C. Glycosidic bond formation D. Introduction of a charged tRNA into an unoccupied A site of the ribosome E. All of the above are part of elongation - answer-C If you isolate a single nucleotide from a nucleic acid chain and determine that the nitrogenous ring structure is adenine, you could say with certainty that the nucleotide could have come from: A. DNA but not RNA B. RNA but not DNA C. Either DNA or RNA D. Neither DNA nor RNA E. Double-stranded DNA but not single stranded DNA - answer-C An intron is: A. A protein that is removed following translation B. A transfer RNA that binds to the codon C. Part of an intact, mature mRNA that leaves the nucleus D. RNA that is removed during the processing of a primary RNA transcript E. A series of amino acids at the end of a new polypeptide that directs transcription to the ER - answer-D A mutation in _____ results in a change in _____ that sometimes produces a(n) _______ with altered structure and function. A. RNA; DNA; protein B. Protein; RNA; DNA C. DNA; RNA; protein D. protein; DNA; RNA E. RNA; protein; DNA - answer-C A type of bacteria is discovered in which the genetic material is a single, circular molecule of double-stranded DNA in which some instances of one of the bases is modified by the addition of a methyl group. One strand is 22% A, 26% T, 18% C, 30% G, 4% M; the other strand is 26% A, 22% T, 25% C, 22% G, and 5% M. Which base was modified? A. Adenine B. Thymine C. Cytosine D. Guanine - answer-C RNA molecules are transported from the nucleus to the cytoplasm in eukaryotes through: A. Nuclear pore complexes B. Sodium/potassium channels C. Passive diffusion D. Budding off of the nuclear envelope E. Aquaporins - answer-A Which one of the following would most likely be a product of a catabolic reaction? A. An enzyme like rubisco B. A nucleotide like uracil C. A motor protein like myosin D. An amino acid like glucose E. Starch - answer-B Which of the following is not an example of potential energy? A. A proton gradient B. The chemical bonds in glucose C. The chemical bonds in a fatty acid tail D. Electrons in an outer cell E. Rotation of the F0 subunit of ATP synthase - answer-E The potential energy in a molecule of ATP is held in the: A. Carbon-carbon bonds of the sugar B. Repulsion of the sugar and the base C. Repulsion of the covalently bonded phosphate groups D. The carbon-nitrogen bonds of the base E. The carbon-oxygen bonds of the sugar - answer-C Which one of the following statements about breaking a peptide bond is correct? A. The reaction is endergonic B. The reaction is catabolic C. The reaction is not spontaneous D. The reaction has a negative delta G E. None of these choices are correct; all of the statements about breaking a peptide bond are incorrect - answer-D Which of the following reactions is most likely to be exergonic? A. The synthesis of a phospholipid from glycerol and fatty acids B. The synthesis of a protein from amino acids C. The breakdown of glucose D. Both A and B E. Both B and C - answer-C The energy of activation of a reaction is: A. The net change in free energy B. The energy input needed to reach the transition state C. Equivalent to the delta G of ATP hydrolysis D. The difference in energy between the transition state and the product. E. The difference in energy between substrate and product - answer-B What is the purpose of an enzyme? A. To slow the rate of a specific reaction B. To decrease the energy required to reach the transition state C. To alter the potential energy of a specific reaction D. To increase the rate of a specific reaction and decrease the energy required to reach the transition state E. None of the above - answer-D True of false: A catalyzed (with an enzyme) and uncatalyzed (without an enzyme) reaction have a different delta G. A. True B. False - answer-B Which of the following types of inhibitor permanently alters the enzyme it inhibits, primarily by forming a covalent bond? A. An inhibitor that changes the shape of the enzyme (conformational change) B. A competitive inhibitor C. An allsteric inhibitor D. Both A and B E. None of the above - answer-D Which of these summarizes the overall reactions of photosynthesis? A. C6H12O6 + 6O2 -- 6CO2 + 6H2O + energy B. 6CO2 + 6O2 -- C6H12O6 + 6H2O C. C6H12O6 + 6O2 + energy -- 6CO2 + 12H2O D. 6CO2 + 6H2O + energy -- C6H12O6 + 6O2 E. H2O -- 2H+ + 1/2O2 + 2e- - answer-D Which of the following reactions would you predict could be coupled to ATP hydrolysis yielding ADP + Pi to make it energetically favorable, or spontaneous? A. Creatine + Pi -- Creatine phosphate + H2O, delta G +10.3 kcal/mol B. Glutamic acid + NH3 -- glutamine, delta G +3.4 kcal/mol C. Glucose 6-phosphate + H2O -- glucose + Pi, delta G -3.3 kcal/mol D. Glucose 1-phosphate + H2O -- glucose + Pi, delta G -5.0 kcal/mol E. Phosphoenolpyruvate + H2O -- pyruvate + Pi, delta G -14.8 kcal/mol - answer-B Carbon dioxide is a waste product of the complete oxidation of glucose. Carbon dioxide ___________ A. is produced during glycolysis, pyruvate oxidation, and the citric acid cycle B. Is produced during pyruvate oxidation (formation of acetyl CoA) and the citric acid cycle C. Is produced when water is oxidized D. Is made up of the carbons that were once part of fatty acid tails E. Reduces the ETC - answer-B Glucose is stored in plants as ________ and in animals as _______ A. Cellulose; starch B. Cellulose; glycogen C. Starch; cellulose D. Starch; glycogen E. Glycogen; starch - answer-D Which of the following statements must be true in order for mitochondrial ATP synthase to function properly? A. There must be no difference in proton concentration between the mitochondrial matrix and the intermembrane space. B. The proton concentration of the intermembrane space must be lower than the proton concentration of the mitochondrial matrix C. The proton concentration of the intermembrane space must be higher than the proton concentration of the mitrochondrial matrix - answer-C Cellular respiration requires oxygen and releases energy. Which of the following statements most accurately summarizes cellular respiration A. Carbohydrates are converted into chemical energy that can be used to do the work of the cell B. Chemical potential energy in the bonds of ADP is transferred to the chemical potential energy in the bonds of ATP C. The chemical potential energy stored in organic molecules (e.g. glucose, lipids, proteins) is converted to chemical energy that can be used to do the work of the cell D. All of the above accurately summarize cellular respiration D. None of the above accurate summarize cellular respiration - answer-C Complete oxidation of glucose to CO2 involves two different mechanisms for synthesizing ATP, oxidative phosphorylation and substrate-level phosphorylation. Which statement is true? A. In substrate-level phosphorylation an enzyme catalyzes the addition of a phosphate group to ATP to form ADP B. Most of ATP generated is due to oxidative phosphorylation C. In oxidative phosphorylation ATP is directly generated when high-energy electrons move from electron carriers through the electron transport chain. D. Oxidative phosphorylation requires an electron gradient. E. All of these statements are true. - answer-B Which one of the following complexes doesn't pump a proton across the membrane? A. Complex I B. Complex II C. Complex III D. Complex IV E. None of these complexes act in this way - answer-B Which of the following is a net product of the citric acid cycle for one of the two pyruvates generated in glycolysis? A. 1 ATP B. 3 NADH C. 1 FADH2 D. A and C E. A, B, and C - answer-E Which regulatory mechanism is important in keeping the electron transport chain and glycolysis in relative balance to each other? A. Citrate upregulates (increases the speed) of the enzyme phophofructokinase 1. B. ADP inhibits phosphofructokinase 1 C. ATP upregulates phosphofructokinase 1 D. AMP upregulates phosphofructomkinase 1 E. None of the above mechanism keep the two processes in relative balance - answer-D During photosynthesis, _____ is oxidized while ______ is reduced. A. Water; carbon dioxide B. Carbon dioxide; oxygen C. Oxygen; water D. Glucose; oxygen E. Carbon dioxide; glucose - answer-A The interior of the thylakoid is referred to as the: A. Cytoplasm B. Grana C. Stroma D. Lumen E. Intermembrane space - answer-D Kanaroo rats live in the desert of the southwestern United States. They have many adaptations to minimize water loss. They obtain a small amount of water from seeds that the eat. However, the rest of the water they obtain is from cellular respiration. A. This cannot be true, as cellular respiration does not really "produce" water B. This cannot be true, as water is actually consumed in cellular respiration C. This could be true, as water is produced in cellular respiration D. This could be true, as water is produced in glycolysis E. This could be true, as water is produced in the citric acid cycle - answer-C Imagine that a cell has completely run out of glucose. What impact will this have on the citric acid cycle? A. Concentrations of acetyl CoA entering the CAC will go up, immediately B. Concentrations of CO2 will immediately begin to go up C. The cell will be able to continue to produce ATP via substrate-level phosphorylation indefinitely D. The cells production of ATP via oxidative phosphorylation will be unaffected E. Concentrations of oxaloacetate (to which acetyl-CoA is added) will go up, while concentrations of citrate begin to go down - answer-E Arrange the steps in the Calvin cycle in order from earliest to latest. A. Carbozylation, redution, regeneration B. Reduction, regeneration, carboxylation C. Regeneration, carboxylation, reduction D. Carboxylation, regeneration, reduction E. Reduction, carboxylation, regeneration - answer-A Regarding the Calvin Cycle of photosynthesis A. Rubisco binds the 5-C RuBP to CO2, immediately producing a 6-C glucose B. Electron carriers are reduced, and ATP is synthesized C. If glucose concentration in the cell were to fall, glyceraldehype-3-phospate levels would rise. D. A portion of the energy delivered by NADP+ is used to generate ATP E. The overall purpose is to reduce CO2 - answer-E A high energy electrons move through the ETC, they take part in many redox reactions. Starting with the electrons delivered from FADH2, place in the proper sequence the molecules below that are reduced by high-energy eletrons. 1. complex 1, 2. complex 2, 3. complex 3, 4. complex 4, 5. cytochrome C, 6. O2, 7. Co-enzyme Q A. 1 2 3 5 4 7 6 B. 1 2 3 4 5 6 7 C. 2 5 3 7 4 6 D. 2 7 3 5 4 6 E. 1 7 2 7 3 5 4 - answer-D Which of the following statements about communication among bacteria is incorrect? A. Cellular communication in bacteria is based on the same principles as communication within multicellular organisms B. Bacterial communication requires a receptor molecule C. Small peptides can stimulate a DNA-uptake response D. At higher population density, a higher concentration of signalling molecules is typically observed E. None of these statements is incorrect - answer-E Mammalian steroid hormones are signalling molecules that function in which of the following types of cell signalling? A. Juxtracrine B. Paracrine C. Autocrine D. Endocrine E. None of the above - answer-D Which type of signal receptor often transmits signals by modifying levels of cyclic-AMP, a second messenger? A. G-protein coupled receptor B. Receptor kinase C. Nuclear receptor D. Ligand-gated ion channel E. All of these use cyclic-AMP as a second messenger - answer-A Consider a mutant form of the EGF receptor kinase called Her2/neu. The mutant form of the receptor kinase is linked to cancer because the receptor molecule is locked in the "on" position. Which of the following mechanisms could cause this to occur? A. The mutant receptor lacks the ability to phosphorylate B. Rather than add phosphate groups the mutant receptor removes phophates (dephosphorylates) C. The mutant receptor dimerizes in the absence of the signalling molecule D. The mutant receptor lacks the ability to dimerize E. The mutant receptor cannot form cylic-AMP - answer-C Phosphatases are family of enzymes that specifically remove phosphate groups from proteins, deactivating them and shutting down a signal. Triuvec is a drug that inhibits phosphates in eurkaryotic cells. What effect would Triuvec have on the response of cells to signals received by G-protein coupled receptors? A. The response of the cell would last longer than it normally would. B. The ligand would still bind the receptor, so there would be no effect C. The ligand would bind the receptor, but the signal wouldn't be transmitted to the nucleus D. The signal would be transmitted, even when the ligand isn't bound. E. The response of the cell cannot be predicted. - answer-A Choose from the following terms to fill in the blanks in the correct order. A. ligand, B. signalling cell, C. receptor, D. responding cell. In communication between cells, the _____ produces the signalling molecule, also know as the _____; the ______ produces the _____ to which the signalling molecule binds. A. B A D C B. A B C D C. B C A D D. D C B A - answer-A The ability of a specific tissue or organ to respond to the presence of a hormone is dependent on A. The location of the tissue or organ with respect to the circulatory path B. The membrane potential of the cells of the target organ C. The presence of the appropriate receptors on the cells of the target tissue or organ D. Nothing. All hormones of the body are able to stimulate all cell types because hormones are powerful and nonspecific . - answer-C Which of the following comparisons between gap junctions and plasmodesmata is not true? A. Both allow exchange of material between cells, but plasmodesmata allow larger-sized molecules to transfer between cells. B. Animal cells have gap junctions, and plant cells have plasomodesmata C. Gap junctions are channels formed by proteins, while in plasodesmata plasma membranes of the connected cells are continuous D. Gap junctions connect cells directly via proteins embedded in the plasma membranes, but plasodesmata must also bridge the cell wall separating the two cells E. All of these comparisons are true - answer-E Which of the following is found in the extracellular matrix of animal cells? A. Cellulose B. Cross-linking fibers C. Collagen fibers D. Lignin E. Polysaccharide matrix - answer-C Which one of the following statements about intracellular transport is true? A. Myosin moves substances toward the "plus end" of microfilaments and kinesin does this same movement in microtubules. B. Myosin moves substances toward the "minus end" of microfilaments and kinesin does this same movement in microtubules. C. Myosin moves substances toward the "plus end" of microtubules and kinesin does this same movement in microfilaments D. Kinesin and myosin both move substances toward the "plus end" of microtubules E. None of these statements is correct - answer-A How does an adherens junction differ from a hemidesmosome? A. Adherens junctions connect a cell to neighboring cells, and hemidesmosomes connect a cell to the extracellular matrix B. Adherens junctions connect cells using adherin proteins, and hemidesmosomes connect cells with cadherin proteins C. While both adherens junctions and hemidesmosomes connect cells by using cadherin proteins, only adherns junctions connect o actin (microfilaments) D. While both adheren junctions and hemidesmosomes connect cells by using integrin proteins, adherens junctions connect to microfilaments while hemidesmosomes connect to intermediate filaments inside the cell E. These two types of junctions only differ in the types of cells where they are used: adherens junctions in fibroblasts, hemidesmosomes in epithelial cells - answer-A If a mutation occurred in the integrin gene so that the extracellular domain (outside the cell) no longer forms attachments, which of the following would occur? A. Integrins in desmosomes would no longer be anchored to microfilaments B. Integrins in adherens junctions would be no longer by anchored to microtubules C. Integrins in hemidesmosomes would no longer be anchored to the extracellular matrix of the basal lamina D. Integrins in desmosomes would not longer be anchored to intermediate filaments E. None of the above would occur - answer-C The small intestine is the site of digestion and absorption of nutrients. A single layer of epithelial cells lines the small intestine. These epithelial cells secrete large quantities of digestive enzymes into the digestive tract. Which of the following features would you expect to find in these epithelial cells? A. They would have an expanded nucleus. B. They would contain large quantities of smooth endoplasmic reticulum. C. They would have large quantities of rough endoplasmic reticulum. D. They would contain large numbers of lysosomes. E. They would have two to three times as many mitochondria as other cells. - answer-C A G-protein with GTP bound to it _____ A. Signals a protein to maintain its shape and conformation B. Directly affects gene expression C. Will use cGMP as a second messenger D. Is in its active state E. Is in an inactive state - answer-D When is NAD+ converted to NADH it is ______; When FADH2 is converted to FAD it is _______. Of these four molecules _____ stores the most energy for use in oxidative phosphorylation. A. Reduced; oxidized; FADH2 B. Oxidized; reduced; NADH C. Reduced; oxidized; NADH D. Oxidized; reduced; FADH2 E. None of the above - answer-C During photosynthesis, the light energy from the Sun is captured and stored in the bonds of A. Oxygen B. Water C. CO2 D. Hemoglobin E. None of the above correctly complete the sentence - answer-E The most abundant protein found in the extracellular matrix of animal cells is _______ A. Collagen B. Pectin C. Cellulose D. Hemoglobin E. Integrin - answer-A Which of the following best explains why acetylcholine produces different effects when signalling at the neuromuscular junction than in smooth muscle surrounding blood vessels in the heart? A. Acetylcholine has the same response but the cells differ in the speed at which the response is shut down. B. In smooth muscle the acetylcholine receptor is inside the cell while the receptor is at the cell surface in the neuromuscular junction C. The acetylcholine signalling molecule differs between smooth muscle and in the neuromuscular junction. D. Different cell types can receive the same signal but the eventual response is dependent on the signal transduction cascade activated in each cell after the signal is received E. All of these explains why the response differs - answer-D You are a cell biologist working on cancer cell signalling. You discover a protein that, when exported by one cell and taken up by adjacent cells, turns healthy cells into cancer cells. In normal healthy cells this same protein is produced, but it remains in the cytosol rather than being exported. Which of the following hypotheses would you test? A. The gene encoding the protein has a mutated promoter in the cancer cells that leads to the overproduction of the protein. B. The targeting peptide in the cancer cells is at the C-terminus of the protein, but the N-terminus of the healthy cells. C. In cancer cells, a mutation in the DNA results in a new signal sequence that is recognized by a signal recognition particle (SRP) D. The cancer cells have mutated nuclear pores that allow mRNAs t that should not leave the nucleus to do so E. None of these are reasonable hypotheses given the observations - answer-C Some diseases, such as Tay-Sachs, are caused by the defective breakdown of cellular components. Which of the following organelles is defective? A. Nucleus B. Golgi apparatus C. Ribosome D. Endoplasmic reticulum E. Lysome - answer-E When we say that DNA replication is semiconservative, we mean that A. only half of an organism's DNA is replicated during each cell division B. When DNA is replicated, each new double helix contains one parental strand and one newly synthesized daughter strand C. When DNA is replicated, one double helix contains both parental strands and one contains two newly synthesized daughter strands. D. Parental DNA stays in the parent cell and daughter DNA ends up in the daughter cell. E. None of the answer options are correct - answer-B The enzyme that releases tension from the parental DNA double helix is A. DNA polymerase B. Helicase C. DNA replicase D. DNA ligase E. None of the above - answer-E Similar to linear DNA, circular DNA replication in most prokaryotes A. Has multiple origins of replication B. Produces between two and many replication bubbles C. Occurs only at a single replication fork D. Produces Okazaki fragments during lagging strand synthesis E. All of the answer options are correct - answer-D Suppose you add fluorescent ribonucleotides (RNA nucleotides) to a cell undergoing DNA replication so that the RNA primers used in DNA synthesis glow when viewed with a fluorescent microscope. You notice that, near each replication fork, one strand glows more than other. Which strand glows more, and why? A. The leading strand glows more because it is elongated nearest the replication fork B. The leading strand glows more because its synthesis is continuous C. The lagging strand glows more because its RNA primer is nearer the replication fork D. The lagging strand glows more because its synthesis is continuous E. None of these answers are correct - answer-C During DNA replication in a cell, RNA primase synthesizes a primer that is complementary to the region in the sequence below in parentheses. 5'-CACAGCA(GAAACCTACAAC)TCATG-3' What is the primer sequence? A. 5-CTTTGGATGTTG-3' B. 5'-GTTGTAGGTTTC-3' C. 5'-CUUUGGAUGUUG-3' D. 5'-GUUGUAGGUUUC-3' - answer-D Which of the following steps in prokaryotic binary fission is correct? A. DNA is replicated in only one direction from a single point on the circular chromosome B. The replicating chromosomes are attached to the plasma membrane C. The cells stops growing during division D. The nuclear envelope is reformed prior to cell division E. All of these statements are correct - answer-B Which of the following are true about gametes? A. They are formed by mitotic cell division B. They have twice as many chromosomes as a somatic cell of the same individual C. They are called eggs and sperm in animals D. They are genetically identical E. All of these statements are true - answer-C The M cyclin-CDK complex: A. Controls the cell cycle during the M and G1 phases B. Initiates many events of synthesis C. Phosphorylates proteins that are important for replicating DNA D. Triggers phosphorylation of certain nuclear proteins, resulting in breakdown of the nuclear envelope during prophase E. All of these choices are correct - answer-D Put the following steps of DNA replication in chronological order 1. Single-stranded binding proteins attach to DNA strands to prevent them from coming back together 2. Helicase breaks hydrogen bonds between base pairs of antiparallel strands 3. Primase binds to the site of origin 4. DNA polymerase binds to the template strand 5. An RNA primer is created A. 1 2 3 4 5 B. 2 1 3 5 4 C. 3 2 1 5 4 D. 2 3 1 5 4 - answer-B Malignancies develop step-wise over time because: A. It takes time for a benign tumor to be able to dissolve through its encapsulation before it can invade neighboring tissues B. Benign tumor cells divide slowly and in a step-wise pattern C. Cells keep leaving the benign tumor and are destroyed in lymph nodes D. It takes multiple mutations of multiple genes to allow cancer cells to rapidly divide and invade tissues as suggested by the multiple mutation model E. All of these choices are correct - answer-D Predict what would happen if a chromosome only connected to the mitotic spindle at one of its kinetochores? A. One of the daughter cells would not have a copy of that chromosome B. The sister chromatids would not separate C. The chromosome would not form a proper tetrad/bivalent D. A and B E. A, B, and C - answer-D Colchicine is a drug that is used in plant breeding. It blocked the assembly of microtubules leading to the arrest of mitosis. If dividing cells are treated with Colchicine, at what stage of mitosis would you predict the arrest would occur (e.g., at what phase are microtubules first apparent)? A. Prophase B. Metaphase C. Late anaphase D. Telophase E. G1 of interphase - answer-A The epithelial cells in the skin of a diploid animal have 24 chromosomes. How many chromosomes are present in the gametes of this animal? A. 6 B. 12 C. 24 D. 48 E. None of the above - answer-B The genetic information of daughter cells is the same as the genetic information of the parent in binary fission and mitosis A. True B. False - answer-A The lines here represent the paired strands of a DNA double helix. If this molecule undergoes one round of replication, which ends are shorter in the daughter molecules than in the parental molecules? 3' W ----------- X 5' 5' Y ------------ Z 5' A. W and X B. W and Y C. W and Z D. Y and X E. Y and Z - answer-C p53 is an example of a(n) A. Oncogene B. Proto-oncogene C. tumor suppressor D. Cyclin-dependent kinase - answer-C The amount of _______ is fairly constant throughout the cell cycle, but the amount of ________ varies. A. Cyclins; cyclin-dependent kinase B. DNA; cyclins C. Cyclin-dependent kinase; DNA D. Cyclin-dependent kinase; cyclins E. Both C and D - answer-E Which of the following statements would be true if a cell has a mutation in the p53 gene such that the p53 protein is always phosphorylated? A. The amount of p53 protein in the nucleus would remain high regardless of the presence of DNA damage, inhibiting movement from G1 to S B. The amount of cytoplasmic p53 protein would increase in response to DNA damage C. The kinase activity in the nucleus would decrease in response to DNA damage D. p53 could not accumulate in the nucleus and the cell would move to S phase E. p53 could not accumulate in the nucleus and synthesis would occur in the presence of DNA damage - answer-A Paramecium is a single-cell eukaryotic organism that can reproduce by mitotic cell division. Before M phase of the cell cycle, which of the following must occur? A. The cell must replicate its chromosomes B. The cell must first be fertilized C. The nucleus must divide D. Sister chromatids must be separated E. The nuclear envelope must disintegrate - answer-A Of the following, the most likely to contribute to uncontrolled cell proliferation (cancer) is: A. A mutant microtubule synthesis/polymerization enzyme B. A mutant cyclin that is always present in the cell C. A mutant CDK that is unable to bind with its cyclin binding partner D. A mutant DNA replication mechanism causing extra chromosome copies E. A mutant kinetochore protein that causes reduced microtubule attachment - answer-B Forensic technicians unearth a skeleton from a shallow grave. They extract a tiny amount of DNA from the pulp found in the teeth. How could they obtain sufficient DNA for an analysis of the victim's genes? A. Subject the DNA to gel electrophoresis B. Use a restriction enyzme C. Subject the specimen to amniocentesis D. Use the polymerase chain reaction to make copies of a specific region of the DNA E. None of these techniques would allow technicians to obtain sufficient DNA - answer-D Match each of the proteins involved in DNA replication with its function. 1. DNA helicase 2. Topoisomerase II 3. Single-stranded binding proteins 4. DNA polymerase ____ Extends DNA nucleotides from an RNA primer ___ Unwinds the DNA duplex ____ Relieves the stress on the replication fork caused by unwinding ____ Proofreads the growing DNA strands and replaces mismatched nucleotides ___ Prevents strands of DNA from rejoining after being unwound A. 1 2 3 4 2 B. 4 2 1 4 3 C. 4 1 2 4 3 D. 4 1 3 4 2 E. None of the above - answer-C One of the two DNA parent strands within a replication bubble (two replication forks) acts as a template strand that produces: A. Either a leading strand or a lagging strand B. Two leading strands or two lagging strands C. One leading strand and one lagging strand D. Only leading strands E. Only lagging strands - answer-C Reactivation of telomerase activity is associated with: A. Aging B. A cell's inability to replicate C. Parkinson's disease D. Diabetes E. Cancer - answer-E Lack of telomerase activity limits what? A. The rate of DNA replication B. The number of replication bubbles that form during replication C. The rate of meiosis D. The number of Okazaki fragments on the leading strand E. The number of times a cell can divide - answer-E Which of these is/are necessary for PCR? A. Template DNA B. DNA helicase C. RNA nucleotides D. Primase E. Both A and C - answer-A Gel electrophoresis separates DNA fragments based on: A. Presence of RNA B. Number of uracils present C. Mutations D. Number of chromosomes E. None of these - answer-E Having two sets of chromosomes in the genome is referred to as: A. Being diploid B. Repeated sequence motif C. The C-value paradox D. Supercoiling E. Polyploidy - answer-A Which one of the following statements about transposable elements is correct? A. They can move locations within the genome B. They were discovered in mice C. They aren't present in plants D. They have no effect on gene expression E. All of the answer options are correct - answer-A Homologous chromosomes can be defined as: A. Pairs of chromosomes that cannot undergo DNA hybridization B. Pairs of chromosomes that have the same genes, in the same order, although the version of the genes may differ C. Pairs of chromosomes that share the same genes but differ in gene order D. Identical double helices of DNA that are products of DNA replication E. Pairs of chromosomes between different species that carry approximately the same genes in the same locations - answer-B You discover a new complex eukaryote from a deep ocean vent. With confidence you can say its genome is: A. Small with few genes B. Small with many genes C. Large with few genes D. Large with many genes E. None of the answer options - answer-E What is the advantage of the proofreading function of DNA polymerase? A. All DNA mutations can be detected and repaired during DNA replication B. DNA polymerase is always present and can repair all mutations when they occur C. DNA polymerase can be recruited to recently mutated sites to repair mutations D. DNA polymerase can repair most mutations as they occur during DNA replication E. Both B and C - answer-D What would happen during cell division if the cell is deficient in actin? A. The sister chromatids would not separate B. The mitotic spindle would not form C. The cell would not divide D. The centromeres would not split E. None of these would occur - answer-C The average mutation rate in humans does not accurately describe the pattern of mutations across the genome because A. Some sites (hotspots) are more mutable than others B. Mutation rates are higher in females than in males C. Mutation rates are higher in germ line cells than in somatic cells D. B and C E. A B and C - answer-A Insertions and deletions that involve one or two nucleotides A. Cause missense mutations B. Cause frameshift mutations C. Add or delete a single amino acid to/from an otherwise normal polypeptide D. Shorten chromosomes E. Cause cancer - answer-B Mismatch repair, base excision repair, and nucleotide excision repair are similar in that: A. Each requires DNA ligase to connect the sugar-phosphate backbone B. Each requires the activity of a polymerase to replace one or more incorrect bases C. Each repairs multiple mismatched or damaged bases across a region D. Each requires the activity of DNA ligase and a DNA polymerase E. Nothing is similar between these three repair mechanisms - answer-D A family can share a genetic risk of developing cancer if: A. The cancer is caused by somatic cell mutations B. The cancer is caused by germ-line mutations in each individual who develops cancer C. A germ-line mutation in one of the genes implicated in the cancer occurred in an ancestor D. A somatic cell mutation in one of the genes implicated in the cancer occurred in an ancestor E. All of these choices are correct - answer-C Match the environmental agent with the type of DNA damage is caused. 1. X-rays 2. UV radiation 3. tobacco smoke 4. exposure to oxidizing agents such as household bleach or H2O2 ____ Addition of bulky sidegroups that hinder proper base pairing ____ Loss a a base from one of the deoxyribose sugars, resulting in a gap in one DNA strand ___ Breaks in one or both of the sugar-phosphate backbones ___ Cross-links between adjacent pyrimidine bases A. 3 4 1 2 B. 4 3 2 1 C. 3 1 3 2 D. 2 4 3 2 E. 3 2 1 4 - answer-A If a population of diploid organisms has three different alleles for a particular gene, how many different homozygous genotypes are possible? A. 2 B. 3 C. 6 D. 12 E. 16 - answer-B True or false: only those mutations that occur in somatic cells can be passed onto progeny A. True B. False - answer-B (Look up amino acid codes) For how many amino acids is it impossible that a synonymous (silent) mutation will occur? A. 2 B. 4 C. 8 D. 12 E 16 - answer-A Which statement about mutations is true? A. Mutations are random events B. Mutations only occur in regions of DNA that don't encode for proteins C. Mutations are always beneficial D. Mutations are always harmful E. Both A and B - answer-A The phenotype of an individual results from an interaction between A. Allele frequency and mutation rate B. Allele frequency and genotype C. Genotype and mutation rate D. Allele frequency and the environment E. Genotype and the environment - answer-E A population of mosquitoes is exposed to the pesticide DDT for several generations. At the end of that time, most individuals in the population are resistant to DDT. The most likely reason is that: A. DDT caused the mutations that led to resistance B. Some individuals in the original population had the mutations that led to resistance C. By chance, new mutations that led to DDT resistance arose after DDT was used D. Somatic mutations in the original population were passed on to subsequent generations E. Random mutations in each generation made mosquitoes resistant to DDT - answer-B UV light is a mutagen, but humans need some exposure to it in order to synthesize vitamin D3. The amount of UV light that penetrates the skin depends on the skin's pigmentation: more melanin means less penetration. Certain mutations result in decreased melanin production. Such mutations: A. Are harmful only if inherited from both parents B. Are beneficial only if inherited from both parents C. Are neutral only if inherited from one parent, not the other D. May be harmful in one environment and beneficial in another - answer-D An individual is heterozygous for a gene if: A. His or her mother is heterozygous for the gene B. His or her father is heterozygous for the gene C. He or she developed from a sperm and egg that carried different alleles D. He or she developed from a sperm and an egg that carried the same allele E. Only one allele is present in the population - answer-C Cancer can be caused by mutations. Genetic analysis of a tumor found in a patient we shall call Anna shows that the cell proliferation was triggered by a somatic mutation in the MYC gene, causing this gene to be inappropriately activated. Anna is concerned by passing this cancer on to the children she plans to have in the future. Should she be concerned? A. Yes, she should worry because the tumor growth was triggered by a genetic change, and mutations are passed n through cell divisions B. No, this is not something to worry about because mutations in cancer cells cannot be passed on in cell division C. No, she should not worry about her children because this did not occur in a germ-line cell - answer-C