Foundations.txt

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Foundations.txt
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Foundations Assessments
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Foundations Assessments
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  1. Immune responses in adaptive immunity
    • A. Are immediate
    • B. Are mediated by a large repertoire of receptors encoded by rearranging genes to recognize a multitude of antigens
    • C. Generate long standing memory
    • D. All of the above
    • E. Only B and C
    • Points Earned: 1/1
    • Correct Answer: E
  2. Which statements are correct?
    • A. Somatic hypermutation does not generate diversity in T cell receptor
    • B. Somatic hypermutation generates diversity in T cell receptor
    • C. Somatic hypermutation does not generate diversity in B cell receptor
    • D. Somatic hypermutation generates diversity in B cell receptor
    • E. A and D
    • Your Response: E
  3. In T cell alloreactivity (such as during transplantation) the following interactions can be observed with non-self MHC
    • A. Peptide dominant binding in the absence of binding to non-self MHC
    • B. non self MHC dominant binding in the absence of binding to peptide fragment in the groove of the MHC
    • C. Peptide dominant binding will never occur without binding to non-self MHC
    • D. MHC dominant binding will not occur without binding to peptide fragment in the groove of the non-self MHC
    • E. A and B
    • Your Response: E
  4. Leukocytes bind to each other or to endothelial cells via the following adhesion molecules
    • A. Selectins which provide strong binding
    • B. Integrins which provide strong binding
    • C. Ig superfamily which are ligands for Integrins
    • D. Selectins which provide weak binding
    • E. Integrins which provide weak binding
    • F. Only B, C and D
    • G. Only A, E and C
    • Points Earned: 1/1
    • Correct Answer: F
    • Your Response: F
  5. The followings are considered secondary lymphoid organs
    • A. Lymph nodes
    • B. Thymus
    • C. Gut associated lymphoid tissues (GALT)
    • D. Bronchial associated lymphoid tissues (BALT)
    • E. A, C and D
    • F. A, B and C
    • Points Earned: 1/1
    • Correct Answer: E
    • Your Response: E
  6. Complement system consists of the following pathways
    • A. Classical and Alternative and Toll like
    • B. MB Lectin, Classical and Toll like
    • C. MB Lectin, Collectin and Toll like
    • D. Classical, Alternative and MB Lectin
    • E. Only A and D
    • F. Only C and D
    • Points Earned: 1/1
    • Correct Answer: D
    • Your Response: D
  7. The followings are pattern recognition receptors
    • A. Mannose-binding Lectin
    • B. B cell antigen receptor
    • C. Toll Like receptors
    • D. NOD
    • E. Answers A, C and D
    • F. Answers A and C
    • Points Earned: 1/1
    • Correct Answer: E
    • Your Response: E
  8. Give example(s) of antigen presenting cell(s)
    • A. B cells, macrophages and dendritic cells
    • B. B cells and dendritic cells
    • C. Thymic epithelial cells, dendritic cells and B cells
    • D. Fibroblasts, endothelial cells and dendritic cells
    • E. Dendritic cells
    • Points Earned: 1/1
    • Correct Answer: A
    • Your Response: A
  9. Immune responses in Innate Immunity
    • A. Are immediate
    • B. Are mediated by triggering of variable receptors on innate immune cells
    • C. Do not generate memory
    • D. All of the above
    • E. A and C
    • Points Earned: 1/1
    • Correct Answer: E
    • Your Response: E
  10. In innate immunity, receptors with specificity for pathogens recognize patterns of repeated structural motifs on pathogens called
    • A. Pathogen-associated molecular patterns (PAMPs)
    • B. pattern recognition receptors
    • C. MB Lectin, Classical and Toll like
    • D. Classical, Alternative and MB Lectin
    • E. Only A and D
    • F. Only C and D
    • Points Earned: 1/1
    • Correct Answer: A
    • Your Response: A
  11. Which statement(s) is (are) true
    • A. All cells except T and NK cells express MHC-Class I
    • B. All cells except Antigen Presenting cells express MHC-Class I
    • C. All cells except Red Blood Cells express MHC-Class I
    • D. All cells except Epithelial cells of the thymus express MHC-Class I
    • E. Answers C and D
    • Points Earned: 1/1
    • Correct Answer: C
    • Your Response: C
  12. Gene recombination ensures the generation of enough
    • A. Diversity within the T and B cell receptors for the recognition of a multitude of antigens
    • B. Diversity within the T cell receptors for the recognition of only non-self antigens
    • C. Diversity for the survival of the human species
    • D. Diversity within the T cell receptors for the recognition of only self antigens
    • E. Both answers A and C, above
    • Points Earned: 1/1
    • Correct Answer: E
    • Your Response: E
  13. The followings are C3 convertases
    • A. C3b and C4b
    • B. C4b and C5b
    • C. C4b2a and C3b
    • D. C4b2a and C3bBb
    • E. C4b2aC3b and (C3b)2Bb
    • F. All of the above
    • Points Earned: 1/1
    • Correct Answer: D
    • Your Response: D
  14. Which statements are true?
    • A. Clonal selection of lymphocytes is the central principal of adaptive immunity
    • B. In clonal selection a single progenitor cell gives rise to a large number of lymphocytes each with a different specificity
    • C. In clonal selection lymphocytes with receptors which are self reactive are deleted
    • D. A, B and C
    • E. Only A and B
    • Points Earned: 1/1
    • Correct Answer: D
    • Your Response: D
  15. Which characteristics of Major Histocompatibility Complex (MHC) provide sufficient diversity to present significant numbers of antigens for the survival of species?
    • A. anchor residues and the length of the peptides
    • B. polymorphism and gene rearrangement
    • C. polygenic nature of MHC and point mutations
    • D. polymorphic and polygenic
    • E. All of the above
    • Points Earned: 1/1
    • Correct Answer: D
    • Your Response: D
  16. Which of the following events is NOT observed in oral cancer?
    • A. Inactivation of cyclin D
    • B. Inactivation of p53
    • C. The overexpression of c-Myc
    • D. Ras mutation
    • E. The overexpression of TGF-alpha
    • Points Earned: 1/1
    • Correct Answer: A
    • Your Response: A
  17. Which of the following proteins has anti-apoptotic function?
    • A. Bcl-xl
    • B. Bad
    • C. Bax
    • D. p53
    • E. Rb
    • Points Earned: 1/1
    • Correct Answer: A
    • Your Response: A
  18. When a ligand binds to a tyrosine kinase receptor, which of the following occurs?
    • A. The receptor dimerizes and transduces its signal to a G protein.
    • B. The receptor dimerizes and activates intrinsic tyrosine kinase activity in its cytoplasmic tail.
    • C. The receptor dimerizes and creates a channel for passage of ion channels.
    • D. The receptor dimerizes and activates phosphatase activity in its cytoplasmic tail.
    • E. The receptor dimerizes and activates guanylate cyclase activity in its cytoplasmic tail.
    • Points Earned: 1/1
    • Correct Answer: B
    • Your Response: B
  19. Which of the following statements is FALSE?
    • A. Rb is a tumor suppressor
    • B. Rb is a transcription factor
    • C. Rb regulates E2F
    • D. Rb can be phosphorylated
    • E. Rb can be dephosphorylated
    • Points Earned: 1/1
    • Correct Answer: B
    • Your Response: B
  20. Which of the following is true about MAP Kinase activation?
    • A. To be activated, MAP Kinase is phosphorylated by MAP Kinase Kinase (MAPKK or MEK) on two (tyrosine and threonine) residues.
    • B. It involves activation of three kinases in series.
    • C. Once activated, MAP Kinase can translocate into the nucleus.
    • D. None of the above.
    • E. All of the above.
    • Points Earned: 1/1
    • Correct Answer: E
    • Your Response: E
  21. Which of the following proteins is a tumor suppressor?
    • A. Bcl-2
    • B. Bad
    • C. Src
    • D. Myc
    • E. E2F
    • Points Earned: 1/1
    • Correct Answer: B
    • Your Response: B
  22. Which of the following statements on protein ubiquitination is FALSE?
    • A. Ubiquitin is a protein
    • B. The non-covalent conjugation of ubiquitin to cellular proteins is called ubiquitination
    • C. E3 has high substrate specificity
    • D. Ubiquitin is attached to lysine residues of substrates
    • E. Several enzymes are involved in protein ubiquitination
    • Points Earned: 1/1
    • Correct Answer: B
    • Your Response: B
  23. Which of the following events does NOT occur in mitosis?
    • A. Chromosome condensation
    • B. Chromosome segregation
    • C. Chromosome replication
    • D. Cytokinesis
    • E. Nuclear envelope breakdown
    • Points Earned: 1/1
    • Correct Answer: C
    • Your Response: C
  24. The phenotype of a yeast (S. pombe) mutant lacking Cdc25 is expected to be:
    • A. Cells are small
    • B. Cells are elongated
    • C. Cells are normal in size
    • D. Some cells are small and some cells are elongated
    • E. None of the above
    • Points Earned: 1/1
    • Correct Answer: B
    • Your Response: B
  25. Which of the following statements is FALSE?
    • A. APC promotes the polyubiquitination of mototic cyclins
    • B. APC promotes the polyubiquitination of Securin
    • C. APC promotes the polyubiquitination of CDK
    • D. Cdh1 is a specificity cofactor of APC
    • E. Cdc20 is a specificity cofactor of APC
    • Points Earned: 1/1
    • Correct Answer: C
    • Your Response: C
  26. Which of the following cellular alterations can cause cancer?
    • A. Inactivation of tumor suppressors
    • B. Resistance to apoptosis
    • C. Insensitivity to antigrowth signals
    • D. Tissue invasion and metastasis
    • E. The activation of cell cycle checkpoints
    • Points Earned: 0/0
    • Correct Answer:
    • Your Response: A
  27. Sweet, bitter and umami taste receptors are:
    • A. Ionotropic receptors.
    • B. Tyrosine kinase receptors.
    • C. G-protein coupled receptors.
    • D. Expressed in distinct regions of the tongue.
    • E. Only expressed in humans.
    • Points Earned: 1/1
    • Correct Answer: C
    • Your Response: C
  28. Which of the following statements is FALSE?
    • A. The activation of E2F is required for G1->S transition
    • B. Cyclin D is required for G1->S transition
    • C. E2F stimulates the transcription of Cyclin E
    • D. E2F stimulates its own synthesis
    • E. E2F stimulates the transcription of Rb
    • Points Earned: 1/1
    • Correct Answer: E
    • Your Response: E
  29. Which of the following statements is FALSE?
    • A. p53 can bind to DNA
    • B. p53 can induce MDM2
    • C. p53 can induce p21
    • D. MDM2 is a E3 ligase of p53
    • E. MDM2 is a tumor suppressor
    • Points Earned: 1/1
    • Correct Answer: E
    • Your Response: E
  30. Which of the following statements is FALSE?
    • A. Cyclin is a protein
    • B. The level of cyclin changes during the cell cycle
    • C. Cyclin has a short half-life
    • D. Cyclin is a kinase
    • E. Cyclin can be modified by ubiquitination
    • Points Earned: 1/1
    • Correct Answer: D
    • Your Response: D
  31. In muscle, ENa is approximately +50 mV and EK is approximately -100 mV. If Vrev of the nicotinic acetylcholine receptor is -25 mV, which of the following statements is TRUE? You may assume that the acetylcholine receptor is equally permeable to Na + and K+.
    • A. At -40 mV, the net current is outward.
    • B. At -25 mV, the net current through the acetylcholine receptor depolarizes the muscle cell.
    • C. Net current through the acetylcholine receptor channel switches from inward to outward during the muscle action potential.
    • D. At 0 mV, the influx of Na+ and the efflux of K+ through the acetylcholine receptor cancel each other out so that the net current through the receptor is 0.
    • E. Doubling the extracellular concentration of K+ has no effect on Vrev of the acetylcholine receptor.
    • Points Earned: 1/1
    • Correct Answer: C
    • Your Response: C
  32. Which statement concerning acetylcholine release at the neuromuscular junction is TRUE?
    • A. Every presynaptic action potential releases the same number of quanta.
    • B. Reducing the concentration of Ca2+ in the synaptic cleft reduces the number of quanta released.
    • C. Adding curare to the synaptic cleft reduces the number of quanta released.
    • D. The term ‘quantal content’ refers to the number of acetylcholine molecules released per vesicle.
    • E. Acetylcholine diffuses across the synaptic cleft and enters the muscle cell through open acetylcholine receptors.
    • Points Earned: 1/1
    • Correct Answer: B
    • Your Response: B
  33. Which of the following statements about phosphorylation is correct?
    • A. Phosphorylation of substrate proteins always results in activation of that protein.
    • B. Phosphorylation of substrate proteins always results in inactivation of that protein.
    • C. Substrate proteins can be phosphorylated at serine, threonine or tyrosine residues.
    • D. Substrate proteins can be phosphorylated at methionine, histidine and phenylalanine residues.
    • E. Phosphatases add phosphate groups to substrate proteins and kinases remove phosphate groups from substrate proteins.
    • Points Earned: 1/1
    • Correct Answer: C
    • Your Response: C
  34. In the nervous system, release of acetylcholine from a presynaptic terminal and subsequent binding to a receptor on the postsynaptic terminal is an example of:
    • A. Autocrine signaling
    • B. Endocrine signaling
    • C. Signaling by plasma membrane-attached proteins
    • D. Paracrine signaling
    • E. None of the above
    • Points Earned: 1/1
    • Correct Answer: D
    • Your Response: D
  35. Consider two axons A and B. The radius of A is 100 μm and the radius of B is 400 μm. Which of the following statements is most likely to be TRUE?
    • A. A stimulus that brings A to threshold may not evoke an action potential in B.
    • B. A stimulus that brings B to threshold may not evoke an action potential in A.
    • C. An action potential in B does not travel as far as an action potential in A.
    • D. An action potential in B does not travel as fast as an action potential in A.
    • E. During propagation, the peak amplitude of an action potential in A declines more than the peak amplitude of an action potential in B.
    • Points Earned: 1/1
    • Correct Answer: A
    • Your Response: A
  36. How does ligand binding to a G-protein coupled receptor transduce a signal to the inside of the cell?
    • A. Ligand binding triggers a conformational change in the receptor, leading to binding of GTP to the gamma subunit of the heterotrimeric G protein, dissociation of the alpha, beta and gamma subunits, and activation of an effector enzyme by the GTP-bound gamma subunit.
    • B. Ligand binding triggers a conformational change in the receptor, leading to binding of GDP to the alpha subunit of the heterotrimeric G protein, dissociation of the alpha, beta and gamma subunits, and activation of an effector enzyme by the GDP-bound alpha subunit.
    • C. Ligand binding triggers a conformational change in the receptor, leading to binding of GTP to the alpha subunit of the heterotrimeric G protein, dissociation of the alpha, beta and gamma subunits, and activation of an effector enzyme by the GTP-bound alpha subunit.
    • D. Ligand binding triggers dimerization of the receptor and provides docking sites for adaptor proteins.
    • E. Ligand binding opens a channel in the receptor, allowing ions to flow from the extracellular fluid into the cytoplasm.
    • Points Earned: 1/1
    • Correct Answer: C
    • Your Response: C
  37. When a ligand binds to a G protein coupled receptor that is coupled to G alpha q containing G proteins, which of the following signaling pathways is activated?
    • A. Adenylate cyclase, cAMP and Protein Kinase A.
    • B. Guanylate cyclase, cGMP and Protein Kinase G.
    • C. Adenylate cyclase, DAG and IP3, Protein Kinase C and Cam Kinase.
    • D. Phospholipase C, DAG and IP3, Protein Kinase C and Cam Kinase.
    • E. Phospholipase C, cAMP and Protein Kinase A.
    • Points Earned: 1/1
    • Correct Answer: D
    • Your Response: D
  38. How is cAMP generated?
    • A. The enzyme adenylate cyclase generates cAMP from ATP.
    • B. A phosphatase converts ATP to cAMP.
    • C. A guanine nucleotide exchange factor (GEF) converts ATP to cAMP.
    • D. cAMP phosphodiesterase converts ATP to cAMP.
    • E. A GTPase activating protein (GAP) converts ATP to cAMP
    • Points Earned: 1/1
    • Correct Answer: A
    • Your Response: A
  39. NFκB is activated by Protein Kinase C. What type of G protein coupled receptor and downstream signal transduction cascade leads to PKC activation?
    • A. G alpha q coupled receptor, phospholipase C activation and cleavage of PIP2 to IP3 and DAG.
    • B. G alpha s coupled receptor, adenylate cyclase activation, and generation of cAMP.
    • C. G alpha s coupled receptor, guanylate cyclase activation and generation of cGMP.
    • D. G alpha i coupled receptor, adenylate cyclase inhibition, and decreases in cAMP.
    • E. G alpha i coupled receptor, guanylate cyclase inhibition, and decreases in cGMP.
    • Points Earned: 1/1
    • Correct Answer: A
    • Your Response: A
  40. Which of the following is true about calmodulin?
    • A. It is a highly conserved protein that binds cAMP.
    • B. It is a highly conserved protein that activates Protein Kinase C.
    • C. It is a highly conserved protein that binds calcium.
    • D. It is a heterotrimeric G-protein.
    • E. It is only present in mammalian cells.
    • Points Earned: 1/1
    • Correct Answer: C
    • Your Response: C
  41. Which of the following is a mechanism for terminating signal transduction?
    • A. Internalization of ligand-bound receptors and degradation in lysosomes.
    • B. Internalization of ligand-bound receptors and sequestration in endosomes.
    • C. Association of the ligand-bound receptor with an inactivating protein.
    • D. All of the above.
    • E. None of the above.
    • Points Earned: 1/1
    • Correct Answer: D
    • Your Response: D
  42. The following statements are true. Which of them supports the conclusion that Ca2+ influx triggers neurotransmitter release at the neuromuscular junction?
    • A. Introducing acetylcholine into the synaptic cleft by means of a pipette depolarizes the muscle cell.
    • B. Applying curare to the neuromuscular junction prevents muscle action potentials.
    • C. Eliminating the presynaptic action potential with a drug that blocks voltage-gated Na+ channels prevents neurotransmitter release.
    • D. Injecting Ca2+ into the presynaptic nerve terminal leads to depolarization of the muscle cell.
    • E. Stimulating the motor neuron causes synaptic vesicles to fuse with the presynaptic membrane.
    • Points Earned: 1/1
    • Correct Answer: D
    • Your Response: D
  43. How is PKA activated to phosphorylate substrate proteins in the nucleus?
    • A. cAMP binds to the catalytic subunits, triggering their activation and translocation into the nucleus.
    • B. cAMP binds to the regulatory subunits, triggering their activation and translocation into the nucleus.
    • C. cAMP phosphodiesterase activates PKA, which translocates into the nucleus.
    • D. cAMP binds to the regulatory subunits, leading to the release of free (kinase active) catalytic subunits. The catalytic subunits translocate into the nucleus.
    • E. ATP binds to the catalytic subunits and activates them. The catalytic subunits translocate into the nucleus.
    • Points Earned: 1/1
    • Correct Answer: D
    • Your Response: D
  44. The figure shown above should be familiar to you from the Synapse Lab. In this experiment, curare (4 μM) was applied to the synaptic cleft. In response to a presynaptic action potential (not shown), the end plate current (EPC, the current through the acetylcholine receptor) and the membrane potential of the postsynaptic muscle cell (Vm) were recorded. Note that the EPC peaks before Vm reaches its maximum value. The best explanation for this is:
    • A. It takes time for acetylcholine to diffuse across the synaptic cleft.
    • B. Even though the EPC reverses direction, Na+ influx through voltage-gated Na+ channels continues to depolarize the muscle cell.
    • C. After acetylcholine receptors open, it takes time for Vm to change.
    • D. Although current amplitude decreases after the peak of the EPC, Na+ influx through acetylcholine receptors continues to depolarize the muscle cell.
    • E. It takes time for voltage-gated Na+ channels to open before the cell reaches threshold.
    • Points Earned: 1/1
    • Correct Answer: D
    • Your Response: D
  45. Which of the following factors could contribute to the absolute and relative refractory periods?
    • A. The afterhyperpolarization is occurring.
    • B. Voltage-gated Na+ channels are inactivated.
    • C. Voltage-gated K+ channels are still open.
    • D. Opening all of the available voltage-gated Na+ channels is not sufficient to bring the cell to threshold.
    • E. All of the above.
    • Points Earned: 0/1
    • Correct Answer: E
    • Your Response: B
  46. Which of the following statements about the movement of materials across a phospholipid bilayer is TRUE?
    • A. Hydrophobic molecules and gases can readily diffuse across a phospholipid bilayer.
    • B. Diffusion of water across a phospholipid bilayer is limited so most water transport requires specific membrane proteins.
    • C. Transport of inorganic ions such as Ca2+, K+, and Na+ requires specific membrane proteins.
    • D. In biological membranes, transport proteins span the phospholipid bilayer.
    • E. All of the above.
    • Points Earned: 1/1
    • Correct Answer: E
  47. Which of the following statements about membrane transporters is FALSE?
    • A. Turnover of the Na+K+-ATPase can generate a net current across the membrane.
    • B. Primary active transporters hydrolyze ATP.
    • C. Secondary active transporters do not expend energy to move their substrates across the membrane.
    • D. Opening of voltage-gated ion channels can generate a net current across the membrane.
    • E. Transport proteins have substrate binding sites that are alternately exposed to opposite sides of the membrane.
    • Points Earned: 0/1
    • Correct Answer: C
  48. The cytoplasm of a cell is approximately 300 mOsm. Consider a cell that is dropped into a solution of 50 mM sucrose, 125 mM NaCl, and 20 mM MgCl2. Which of the following statements is FALSE?
    • A. There will be net movement of water across the cell membrane.
    • B. The osmolarity of the solution is 340 mOsm.
    • C. The osmolarity of the solution is 360 mOsm.
    • D. The cell will shrink.
    • E. All of the above.
    • Points Earned: 1/1
    • Correct Answer: B
  49. Which statement best describes the difference between downhill mediated transporters and ion channels?
    • A. Downhill mediated transporters must undergo a conformational change every time a substrate moves across the membrane whereas lots of ions cross the membrane when a channel is open.
    • B. Downhill mediated transporters rotate in the membrane whereas channels do not.
    • C. Downhill mediated transporters are driven by ATP hydrolysis whereas channels open and close in response to changes in voltage or ligand binding.
    • D. Downhill mediated transporters have higher turnover numbers than channels.
    • E. Downhill mediated transporters move their substrates toward equilibrium whereas channels use the potential energy stored in ion gradients to move their substrates away from equilibrium.
    • Points Earned: 1/1
    • Correct Answer: A
  50. Which of the following statements about action potential propagation is FALSE?
    • A. Action potentials propagate with no change in waveform.
    • B. Myelination increases conduction velocity by increasing the contribution of passive ion flow to action potential propagation.
    • C. Reinitiating an action potential in an adjacent patch of membrane is slow because it takes time for Na+ channels to open.
    • D. Action potentials don’t back propagate because voltage-gated K+ channels that opened during the action potential are still open.
    • E. None of the above.
    • Points Earned: 0/1
    • Correct Answer: D
  51. Pick the best answer for the following statement: Current amplitude though a highly-selective K+ channel equals zero when
    • A. All the channels are closed.
    • B. The driving force on Na+ is zero.
    • C. The driving force on K+ is zero.
    • D. The driving force on K+ and Na+ is zero.
    • E. All the channels are closed or the driving force on K+ is zero.
    • Points Earned: 1/1
    • Correct Answer: E
  52. Consider the following information: 1) The cytoplasm contains 150 mM K+, 15 mM Na+, and 5 mM Cl-; 2) The extracellular fluid contains 5 mM K+, 140 mM Na+, and 150 mM Cl-; and 3) The relative permeabilities of the ions are: PK = 100; PNa = 5; and PCl = 100. Which of the following statements is TRUE?
    • A. The cell has achieved a Gibbs-Donnan equilibrium.
    • B. Vm = EK = ECl = -86 mV.
    • C. K+ and Cl- are at equilibrium but Na+ is not.
    • D. All of the ions are at equilibrium.
    • E. None of the ions is at equilibrium.
    • Points Earned: 1/1
    • Correct Answer: E
  53. When applied to action potentials, the word ‘regenerative’ means:
    • A. Voltage-dependent opening of Na+ channels leads to Na+ influx which increases the depolarization and opens more Na+ channels.
    • B. Repolarization of the membrane potential allows Na+ channels to recover from inactivation so they are ready for the next action potential.
    • C. Delayed opening of K+ channels contributes to repolarization of the action potential.
    • D. After an action potential, the Na+-K+-ATPase reestablishes the gradients of Na+ and K+ across the membrane so that another action potential can be fired.
    • E. A, B, and C only.
    • Points Earned: 0/1
    • Correct Answer: A
  54. The afterhyperpolarization (also called the undershoot) is due to:
    • A. Inactivation of voltage-gated Na+ channels.
    • B. Opening of K+ leak channels.
    • C. Increased K+ permeability compared to resting conditions.
    • D. A change in EK due to K+ efflux during the action potential.
    • E. C and D.
    • Points Earned: 1/1
    • Correct Answer: C
  55. Which of the following statements best describes the resting membrane potential in a typical living cell?
    • A. At the resting membrane potential all ion channels are closed.
    • B. At the resting membrane potential K+ is at equilibrium.
    • C. At the resting potential the permeability of the membrane to K+ is zero.
    • D. At the resting membrane potential there is no net ion flux across the membrane.
    • E. All of the above.
    • Points Earned: 1/1
    • Correct Answer: D
  56. Which of the following statements about graded potentials is TRUE?
    • A. Graded potentials can be depolarizing or hyperpolarizing.
    • B. The amplitude of a graded potential depends on the amplitude of the stimulus.
    • C. Graded potentials decay with distance.
    • D. Graded potentials spread by passive flow of ions through the cytoplasm.
    • E. All of the above.
    • Points Earned: 1/1
    • Correct Answer: E
  57. Which of the following statements about the Nernst equation is FALSE?
    • A. The Nernst equation is used to calculate the voltage at which an ion feels no net force.
    • B. The Nernst equation is used to calculate the resting membrane potential of a typical living cell based on the K+ concentration gradient.
    • C. The Nernst equation is useful for figuring out which direction an ion will flow across the membrane at the resting membrane potential.
    • D. The Nernst potential for K+ (EK) depends on the K+ concentration gradient.
    • E. None of the above.
    • Correct Answer: B
  58. If the equilibrium potential for Na+ (ENa) is +56 mV and the equilibrium potential for K+ (EK) is -86, which of the following statements is TRUE?
    • A. Opening a Na+ channel at -25 mV leads to net Na+ efflux.
    • B. Opening a K+ channel at +15 mV leads to net K+ influx.
    • C. Opening a Na+ channel at +65 mV leads to net Na+ influx.
    • D. Opening a K+ channel at -100 mV leads to net K+ influx.
    • E. Opening a Na+ channel at +56 mV leads to net Na+ influx.
    • Correct Answer D
  59. Which of the following statements about voltage-gated ion channels is FALSE?
    • A. Voltage-gated ion channels have a high selectivity for particular ions.
    • B. Voltage-gated ion channels open with membrane depolarization.
    • C. Voltage-gated ion channels open and close instantaneously.
    • D. Each voltage-gated ion channel has four voltage sensors and one pore.
    • E. Voltage-gated ion channels contain an unusual transmembrane segment with positively-charged amino acid residues.
    • Correct Answer C
  60. Which of the following statements about action potentials is most accurate?
    • A. There is a net efflux of Na+ during the depolarizing phase of an action potential.
    • B. There is a net efflux of Na+ during the repolarizing phase of an action potential.
    • C. Na+ channel inactivation is maximal at the peak of the action potential.
    • D. There is a net efflux of K+ during the repolarizing phase of an action potential.
    • E. During an action potential, the membrane voltage moves from EK to ENa and back again.
    • Points Earned: 1/1
    • Correct Answer: D
    • Your Response: D
  61. Which of the following statements about diffusion is FALSE?
    • A. Diffusion is due to the random thermal movement of molecules.
    • B. The movement of molecules from a region of higher concentration to a region of lower concentration is probabilistic.
    • C. The diffusion coefficient of glucose, which has units of cm2/sec, is different in water and glycerol.
    • D. Glucose diffuses through water with an average speed of about 240 meters per second. That means that it only takes a fraction of a second for glucose to diffuse from the gastrointestinal tract to the brain.
    • E. None of the above.
    • Points Earned: 1/1
    • Correct Answer: D
  62. Which of the following is a NOT basic step in protein transport through the secretory pathway?
    • A. Protein synthesis and translocation into the endoplasmic reticulum.
    • B. Protein synthesis and folding in the cytoplasm.
    • C. Protein folding in the endoplasmic reticulum.
    • D. Vesicle budding.
    • E. Vesicle fusion.
    • Points Earned: 1/1
    • Correct Answer: B
  63. During the production of type I collagen fibrils, which of these steps happens LAST?
    • A. Removal of the signal peptide from pre-pro-collagen in the endoplasmic reticulum
    • B. Formation of triple helical collagen molecules
    • C. Lysyl oxidase-mediated cross-linking of collagen molecules
    • D. Removal of the N- and C-terminal pro-peptides by extracellular enzymes
    • E. Self-assembly of collagen molecules into staggered arrays
    • Points Earned: 1/1
    • Correct Answer: C
  64. Which of the following statements about biological membranes is FALSE?
    • A. When glycerophospholipids form bilayers, the entropy of water is increased.
    • B. Glycerophospholipids have high mobility in the plane of the membrane but generally do not flip spontaneously from one side of the bilayer to the other.
    • C. The surface of a transmembrane protein is likely to be uniformly hydrophobic.
    • D. In membrane proteins, transmembrane segments tend to form alpha-helices because this secondary structure satisfies the hydrogen bonding requirements of carbon and nitrogen atoms in the peptide background.
    • E. Oxygen (O2), carbon dioxide (CO2), and nitrogen (N2) are able to move across membranes without the assistance of membrane proteins.
    • Points Earned: 1/1
    • Correct Answer: C
  65. Most protein sorting signals are short stretches of amino acids. Which one of the following sorting signals does not consist of amino acids?
    • A. Sorting signal for sorting mannos-6-phosphate receptors into clathrin coated vesicle at the trans Golgi network.
    • B. Sorting signal for import into mitochondria.
    • C. Sorting signal for sorting soluble lysosomal enzymes into clathrin coated vesicle at the trans Golgi network.
    • D. Sorting signal for import into the nucleus.
    • E. Signal sequence for translocation into the ER.
    • Points Earned: 0/1
    • Correct Answer: C
  66. Which one of the following statements about the structure of collagen is FALSE?
    • A. Collagen molecules are comprised of three alpha chains.
    • B. Bulky proline residues contribute to the secondary structure of each alpha chain.
    • C. Close-packing of glycine residues enables the formation of triple helical collagen.
    • D. Covalent bonds between glycine and proline residues stabilize triple helical collagen.
    • E. The presence of hydroxyproline stabilizes triple helical collagen.
    • Points Earned: 1/1
    • Correct Answer: D
  67. Which of the following events in translational elongation is NOT correct?
    • A. The synthesized peptide attached to a tRNA is present at the P (peptide) site of the ribosome.
    • B. Ribosome association of amino acyl-tRNA during elongation is regulated by a GTPase switch protein.
    • C. The charged amino acyl-tRNA based pairs with the mRNA at the A (acceptor) site.
    • D. Peptide bond formation is catalyzed by a ribosomal protein in the small subunit.
    • E. mRNA translocation occurs after peptide bond formation.
    • Points Earned: 1/1
    • Correct Answer: D
  68. Which one of the following statements about elastic fibers if FALSE?
    • A. Elastic fibers allow tissues to stretch and recoil.
    • B. Elastic fibers are mainly comprised of elastin and fibrillin.
    • C. Glycine and proline-rich repeats account for the fixed tertiary structure of elastin.
    • D. Lysyl oxidase is needed to cross-link elastin molecules.
    • E. Genetic mutations that affect elastic fibers can cause heart and lung complications.
    • Points Earned: 1/1
    • Correct Answer: C
  69. Which feature of mRNA is especially important for the initation step of translation?
    • A. PolyA tail
    • B. 3’ untranslated region
    • C. Stop codon
    • D. The free OH group at the 3’ end of the mRNA
    • E. 5’ cap
    • Points Earned: 1/1
    • Correct Answer: E
  70. Which one of the following statements is FALSE?
    • A. Cargo proteins cluster together before coat assembly.
    • B. Coat proteins polymerize onto the cytoplasmic face of a membrane.
    • C. Once coated vesicle form, the coat is depolymerized.
    • D. Tethers act before SNARE proteins.
    • E. There are vesicle and target membrane SNARE proteins.
    • Points Earned: 1/1
    • Correct Answer: A
  71. Which molecule is NOT part of the major shock-absorbing complex in cartilage?
    • A. Chondroitin sulfate
    • B. Keratin sulfate
    • C. Aggrecan
    • D. Hyaluronan
    • E. Laminin
    • Points Earned: 1/1
    • Correct Answer: E
  72. Which of the following statements about the mineralization of teeth is FALSE?
    • A. Hydroxylapatite is the mineralized form of calcium phosphate found in enamel.
    • B. Amelogenins promote the growth of hydroxylapatite crystals.
    • C. Amelogenins replenish minerals lost from enamel over time.
    • D. Dentin phosphoprotein (DPP) chelates calcium and binds collagen.
    • E. Mature enamel contains almost no collagen.
    • Points Earned: 1/1
    • Correct Answer: C
  73. Which of the following is NOT true for tRNA charging with an amino acid?
    • A. It is catalyzed by an enzyme that can bind both the tRNA and amino acid
    • B. It is a two step process
    • C. The amino acid can be joined to the 3’ OH of the tRNA
    • D. one tRNA can be charged with more than one type of amino acid
    • E. The alpha carboxy group of the amino acid is joined to the tRNA
    • Points Earned: 1/1
    • Correct Answer: D
  74. A neutral molecule, Y, is at a concentration of 40 mM (C1) on one side of a barrier, and a concentration of 30 mM (C2) on the other side. The barrier is freely permeable to Y and has an area A and a thickness Δx. If C1, A, and Δx are simultaneously doubled, the net flux of Y would:
    • A. Increase by a factor of 10.
    • B. Increase by a factor of 5.
    • C. Increase by a factor of 2.5.
    • D. Increase by a factor of 1.5.
    • E. Not change.
    • Points Earned: 1/1
    • Correct Answer: B
  75. Osteogenesis Imperfecta (OI) is a genetic disease characterized by brittle bones. Which of the following mutations would you expect to find in a patient with SEVERE OI?
    • A. A missense mutation in COL1A1 that specifies the substitution Gly353Asp.
    • B. A missense mutation in COL1A1 that specifies the substitution Gly1100Asp.
    • C. A missense mutation in COL1A2 that specifies the substitution Gly350Val.
    • D. A missense mutation in COL4A5 that specifies the substitution Gly406Asp.
    • E. A missense mutation in COL4A5 that specifies the substitution Gly1193Asp.
    • Points Earned: 1/1
    • Correct Answer: B
  76. Which of the following statements about chromatin is FALSE?
    • A. Chromatin is more compact than naked DNA
    • B. Chromatin contains histones, which are small basic proteins
    • C. In chromatin DNA is packed withing a protein shell of histones
    • D. In chromatin nucleosomes are packed into a solenoid structure
    • E. Chromatin structure can influence transcription
    • Points Earned: 1/1
    • Correct Answer: C
  77. Which of the following is TRUE for the last amino acid but not other amino acids in a polypeptide chain?
    • A. Contains a free alpha-amino group
    • B. Contains a free alpha-carboxy group
    • C. Contains a negatively-charged side chain
    • D. Contains a positively-charged side chain
    • E. Is always a cysteine
    • Points Earned: 1/1
    • Correct Answer: B
  78. Hydrogen bonds contribute to all of the following EXCEPT:
    • A. Stability of an alpha helix
    • B. Stability of a beta sheet
    • C. Stability of a beta turn
    • D. Stability of a disulfide bond
    • E. Stability of the abnormal, disease-causing form of the prion protein
    • Points Earned: 1/1
    • Correct Answer: D
  79. Which of the following is NOT true of splicing?
    • A. The 5’ splice site and the branch point are recognized by components of the spliceosome
    • B. The phosphodiester bond between the last nucleotide in the exon and the first nucleotide in the intron is cleaved.
    • C. A 3’ to 5’ phosphodiester bond is formed between the branch point A and the first nucleotide of the intron
    • D. The intron is looped to form a lariat structure
    • E. The same RNA can be spliced differently in different cell types
    • Points Earned: 1/1
    • Correct Answer: C
  80. Which part of the nucleotides in DNA are involved in base-pairing
    • A. The phosphates
    • B. The deoxyribose rings
    • C. The organic bases
    • D. Uracil
    • E. Phosphodiester bonds
    • Points Earned: 1/1
    • Correct Answer: C
  81. Which of the following is NOT true of prions?
    • A. They consist of an abnormally folded form of a cellular protein
    • B. The pathological prion protein has a different amino acid sequence than the normal cellular form of the protein
    • C. Prions cause neurodegenerative disease
    • D. The prion form of the protein has a different secondary structure than the cellular form
    • E. The prion form of the protein forms fiber
    • Points Earned: 1/1
    • Correct Answer: B
  82. Which one of the following elements are NOT present in the mature mRNA?
    • A. exons
    • B. promoter
    • C. 3’ UTR
    • D. polyA tail
    • E. 5’ cap
    • Points Earned: 1/1
    • Correct Answer: B
  83. Inheritance as a dominant-positive mutation means that:
    • A. Disease occurs only in individuals homozygous for the mutant allele
    • B. Disease occurs only in individuals homozygous for the normal allele
    • C. Disease occurs in individuals heterozygous for the mutant allele
    • D. Disease occurs only in individuals with somatic mutations
    • E. Disease occurs only in individuals who are hemizygous
    • Points Earned: 0/1
    • Correct Answer: C
  84. In which amino acid is the side chain joined to the alpha amino group?
    • A. glycine
    • B. proline
    • C. cysteine
    • D. tryptophan
    • E. leucine
    • Points Earned: 1/1
    • Correct Answer: B
  85. Mediator plays an important role in transcription initiation because:
    • A. It directly binds to enhancer elements
    • B. It directly binds to silencer elements
    • C. It links transcriptional activators and general transcription factors
    • D. It directly binds to the TATA box
    • E. It separates the DNA strands
    • Points Earned: 1/1
    • Correct Answer: C
  86. Which of the following are NOT copied by RNA polymerase II during transcription of a gene?
    • A. Introns
    • B. Exons
    • C. 5’ untranslated region
    • D. 3’ untranslated region
    • E. TATA box
    • Points Earned: 1/1
    • Correct Answer: E
  87. Which of the following does not involve cleavage of a 3’-5’ phosphodiester bond?
    • A. Alternative splicing
    • B. The first step of splicing that involves formation of a lariat structure
    • C. polyA tail formation
    • D. Histone acetylation
    • E. The last step of splicing that joins two exons together
    • Points Earned: 1/1
    • Correct Answer: D
  88. Which feature of hemoglobin is most responsible for cooperative oxygen binding and release?
    • A. Secondary structure of the hemoglobin subunits.
    • B. The primary structure of the hemoglobin subunits.
    • C. The quarternary structure of hemoglobin.
    • D. The presence of heme in the hemoglobin subunits.
    • E. The similar tertiary structure of myoblobin and the hemoglobin subunits.
    • Points Earned: 1/1
    • Correct Answer: C
  89. Which of the following does NOT require formation of a 3’ to 5’ phospodiester bond?
    • A. The last step of splicing that joins two exons together
    • B. Lariat formation during the first step of mRNA splicing
    • C. Transcription by RNA polymerase I
    • D. polyA tail synthesis
    • E. Transcription by RNA polymerase II
    • Points Earned: 1/1
    • Correct Answer: B
  90. All of the following are important for mRNA transcription initiation EXCEPT:
    • A.Chromatin structure
    • B.RNA polymerase II
    • C.Promoter proximal element
    • D.5’ untranslated region
    • E.TFIID
    • Points Earned:1/1
    • Correct Answer:D

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