HELP WITH THE FOLLOWING MULTIPLE-CHOICE PLEASE

IMPORTANT: THIS IS FROM PREVIOUS EXAMS (not submitting, only practice)

6. Capacitors and batteries are similar because...

A) Both can generate voltage.

B) Both will deplete their voltage when driving current through an electrical circuit.

C) Both consist of a thin insulator between two conductive plates.

D) Both have the ability to drive current through a resistor.

E) Answers B and D are true.

9. Which of the following statements about the Nernst equation is false?

A) It provides the voltage (i.e. equilibrium potential) at which a given ion concentration gradient remains stable across the cell membrane.

B) It reveals that the equilibrium potential for a given ion (i.e. Eion) is dependent on the ambient temperature and the charge of the ion.

C) It provides the voltage resulting from the passive flow of ions across the cell membrane, given a fixed concentration ratio (i.e. [Ion]in / [Ion]out).

D) It assumes that the ion in question is able to passively diffuse across the cell membrane.

E) It integrates the kinetic energy that causes ions to diffuse to regions of low concentration, with electrical potential energy that exerts force on said ions in solution.

14. Which statement about macroscopic whole-cell currents is true?

A) Result from summing multiple currents recorded through a single ion channel multiple times separately.

B) Can be recorded in the squid giant axon using the voltage-clamp technique.

C) Reveal the stochastic properties of single channel activation and inactivation.

D) Can be recorded using inside-out and/or outside-out patch configurations.

E) Where first recorded by Neher and Sakmann.

16. The voltage-clamp technique invented by Kenneth Cole was an important technological advancement because...

A) It allowed Hodgkin and Huxley to record the resting membrane potential of a neuron (the squid giant axon).

B)It allowed Hodgkin and Huxley to record Na+ and K+ currents across the axonal membrane at different depolarizing voltages.

C) It allowed Hodgkin and Huxley to record action potentials in the presence/absence of external Na+ ions.

D) It allowed Hodgkin and Keynes to test Bernstien's hypothesis on the ionic basis of resting membrane potential.

E) All of the above are true.

18. Which of the following statement(s) about Hodgkin and Huxley's equations shown below is false?

A) Contain parameters n, m and h, which account for changes in time and membrane voltage.

B) Were developed to simulate macroscopic Nav and Kv channel currents recorded using the voltage-clamp technique.

C) Were used by Hodgkin and Huxley to predict the trajectory of membrane voltage (Vm) during an action potential.

D) Were made possible by Hodgkin and Huxley's analysis of voltage-sensitive Na+ and K+ currents recorded from the squid giant axon using the voltage clamp technique.

E) The parameter h accounts for voltage-gated sodium channel inactivation.

Equation 1: GK(t)=GK(max)n4 Equation 2: GNa(t)=GNa(max)m3h

19. Which of the following statements about the equation below, which defines the axial/cytoplasmic resistance (Ra) of a section of axon with radius r, length l, and specific axial resistance (Rsa), is false?

A) Large radius axons, such as the squid giant axon, have low Ra.

B) Specific axial resistance (Rsa) is dependent on the electrolyte concentration of the cytoplasm, where higher salt concentrations cause lower Rsa values.

C) Decreasing the surface area of a cross section of axon increases the axial resistance Ra.

D) The radius or length of an axon has no bearing on Rsa.

E) The axial resistance Ra is dependent on the surface area of the cell membrane present in the section of axon.

20. Which of the following statements about the equation below, which defines the length constant () of an axon based on its radius r, length l, specific membrane resistance (Rsm) and specific axial resistance (Rsa) is false?

A) Changing the axon's length does not influence the length constant.

B) Increasing the salt concentration of the cytoplasm decreases the length constant.

C) increasing the density of leak channels in the membrane decreases the length constant.

D) The length constant of an axon is independent of the membrane capacitance.

E) Axons with higher transmit faster action potentials.

=

21. The squid giant axon...

A) Is involved in the predatory behavior of the squid.

B) Has a larger membrane capacitance that would speed up the spread of membrane depolarization along the length of the axon during an action potential.

C) Has a lowered membrane resistance due to its large radius.

D) Is a unique type of axon structure only found in squids.

E) All of the above are true.

22. Which of the following statements about SK and BK channels is true?

A) BK channels activation does not depend on membrane voltage.

B) SK and BK channel activation is not dependent on cytoplasmic Ca2+ influx.

C) SK channels bear calmodulin binding sites within their cytoplasmic regions, serving as a Ca2+ sensor, while BK channels bear Ca2+ sensor "Ca2+ bowl motifs" in their C-termini.

D) Upon activation, SK and BK channels promote cellular excitability.

E) SK and BK channels are both cys-loop channels.

23. Which if the following statements about pannexins/connexins/innexins is false?

A) Pannexins do not form gap junctions, only hemi-channels.

B) Innexins are homologous to connexins.

C) Innexins form gap junctions via innexon coupling in invertebrates.

D) Gap junctions in the central nervous system are used for fast electrical synaptic transmission.

E) Hemi-channels can be used to leak ATP into the extracellular environment.

24. The frequency of action potentials in a tonically firing neuron...

A) Can be increased by increasing Na+ leak conductances which depolarizes the cell membrane.

B) Can be increased by decreasing K+ leak conductances which depolarizes the cell membrane.

C) Can encode information about the strength of a sensory stimulus (e.g. light intensity in retinal ganglion cells).

D) Is dynamically regulated in neurons, via turning Na+ and K+ leak conductances up or down.

E) All of the above are true.

25. Chemical neuron-to-neuron and neuron-to-muscle synapses...

A) Both have prominent post-synaptic densities on electron micrographs caused by clustering of various scaffolding proteins, neurotransmitter receptors, and signaling proteins.

B) Both have post-junctional folds where Cys-loop acetylcholine receptors are localized.

C) All have a basal lamina in the synaptic cleft containing the enzyme acetylcholinesterase.

D) Both have dendritic spines which serve as specialised sites for synaptic transmission.

E) Both use Cav2 type channels to drive pre-synaptic exocytosis of neurotransmitters.

26. Which of the following statements about acetylcholine receptors (AChRs) at the vertebrate neuromuscular junction is false?

A) Curare, a plant extract, contains an active compound turbocuranine that competes with AChRs to block ligand activation and channel opening.

B) -bungarotoxin is a snake peptide toxin that irreversibly binds AChRs, which was used to biochemically isolate the receptor complexes from electric organs of torpedo rays.

C) AChRs are distributed throughout the entire membrane of the post-synaptic muscle fiber.

D) Ionophoresis of acetylcholine onto a collagenase de-innervated muscle fiber only generates excitatory potentials when applied right over or in very close proximity to the craters of the motor end plate.

E) Fluorescent -bungarotoxin applied to muscle fibers only labels the neuron-muscle contact sites of the motor end plate.

27. In the vertebrate CNS, the predominant form of excitatory chemical synaptic transmission is mediated by...

A) Acetylcholine mediated activation of cys-loop acetylcholine receptors.

B) Glutamate mediated activation of Kainate receptors.

C) Serotonin activation of 5-HT3 receptors.

D) Glutamate mediated activation of AMPA receptors.

E) Glutamate mediated activation of NMDA receptors.

28. Pre-synaptic inhibition involves...

A) An inhibitory synaptic potential (IPSP) arriving just before an action potential at an excitatory neuron's axon terminal.

B) An inhibitory synaptic potential (IPSP) arrives just after an action potential at an excitatory neuron's axon terminal.

C) Activation of extra-synaptic GABAB receptors, which inhibits pre-synaptic Cav channels and vesicle exocytosis.

D) Inhibition of the synapse by experimental application of a compound that blocks pre-synaptic secretion.

E) All of the above.

29. Linas' experiments on synaptic delay at the squid giant synapse revealed that...

A) Synaptic delay could be largely accounted for by pre-synaptic activation of Cav channels and Ca2+ influx. B) Was not influenced by temperature.

C) Was faster at colder temperatures than at warm temperatures.

D) Could be largely accounted for by the diffusion of neurotransmitters across the synaptic cleft.

E) Na+ and K+ movement across the membrane plays a direct role in the pre-synaptic release of neurotransmitters.

30. Which of the following statements about synaptic transmission is false?

A) Ionotropic synaptic transmission involves ligand activation of ion channels.

B) Metabotropic synaptic transmission involves activation of G-protein coupled receptors.

C) Metabotropic synaptic processes are slower than ionotropic processes.

D) Acetylcholine is the main neurotransmitter at the vertebrate neuromuscular junction.

E) Glycine is the major inhibitory neurotransmitter in the vertebrate brain.

31. Examples of membrane-delimited G protein signaling include...

A) G potentiation of GIRK channel activity.

B) G inhibition of presynaptic Cav2 channels.

C) Potentiation of Cav1 channels in cardiomyocytes via protein kinase A.

D) All of the above.

E) Answers A and B.

32. Cardiac action potentials exhibit a prolonged depolarization (afterdepolarization) because...

A) High voltage-activated Cav1 channels open during the action potential, delaying the repolarization phase.

B) HCN channels reduce the amplitude and duration of the action potential undershoot.

C) Cardiomyocytes do not express voltage-gated Kv channels.

D) G-protein coupled receptors activate G protein subunits, which potentiate Cav1 channel activity.

E) Low voltage-activated calcium (Cav) channels activate at the peak of the action potential and prolong action potential membrane depolarization.

33. Vertebrate heart sino-atrial (SA) node cells...

A) Respond to acetylcholine by decreasing action potential frequency and hence heart rate, via activation of a K+ current.

B) Respond to norepinephrine by increasing heart rate, via elevation of cAMP levels and HCN channel activity.

C) Respond to acetylcholine by decreasing heart rate, via decreased cAMP levels and HCN channel activity.

D) Receive synaptic inputs from the Vagus nerve of the sympathetic nervous system. E) All of the above are true.

34. Silent glutamatergic synapses...

A) Require coincident depolarization of the post-synaptic cell with pre-synaptic release of glutamate to become active.

B) Require NMDA receptor trafficking to the post-synaptic membrane to become active, which is dependent on calmodulin kinase II (CaMKII).

C) Are silent because post-synaptic AMPA receptors have a voltage-dependent Mg2+ block that prevents them from responding to glutamate in the synaptic cleft.

D) Are silent because of G protein subunit inhibition of pre-synaptic Cav2 channels.

E) All of the above statements are true.

35. Which of the following statements about ionotropic glutamate receptors is false?

A) Include NMDA receptors, which exhibit voltage-dependent block by Mg2+.

B) Include AMPA receptors, which are mostly selective for Ca+ ions.

C) Include Kainate receptors, which play a minor role in excitatory transmission in the vertebrate brain compared to AMPA receptors.

D) Are crucial for synaptic plasticity for learning and memory (in particular NMDA and AMPA receptors).

E) Are thought to have evolved from P-loop channels via inversion across the cell membrane.

36. Which of the following statements about indirect synaptic transmission is false?

A) It is a fast form of synaptic transmission mediated by direct activation of ionotropic receptors.

B) It is a form of slow synaptic transmission mediated by direct activation of GPCRs.

C) It is ubiquitous in the central nervous system, where it serves to modulate direct synaptic transmission over extended periods of time.

D) It is distinct from electrical synaptic transmission where gap junctions permit electrical signals to travel directly from one neuron to another.

E) It often leads to modulation of ion channel activity via various intracellular signaling pathways.

37. G protein coupled receptors...

A) Are a large family of transmembrane receptors bearing 6 transmembrane helices (S1 to S6 helices).

B) Are unique to animals.

C) Can be activated by various ligands, including small molecules, light, proteolysis and cell adhesion.

D) Directly interact with calmodulin in the cytoplasm, which acts as a second messenger.

E) Conduct ions across the membrane upon ligand activation.

38. Hyperpolarization-activated cyclic nucleotide-gated (HCN) channels are...

A) Structurally similar to voltage-gated K+ P-loop channels (Kv channels). B) Sensitive to intracellular Ca2+ concentration.

C) Pentameric channel structures made up of five separate protein subunits. D) Only expressed in the central nervous system, and not the heart.

E) All of the above answers are false.

39. G protein modulation of M-type K+ channels involves...

A) Activation of Gq and phospholipase C, which cleaves and depletes the endogenous membrane bound M-type channel agonist PIP2.

B) Activation of the Go G complex, which enhances M-type channel activity.

C) Activation of adenylyl cyclase, which produces M-type channel intracellular activator cAMP.

D) Activation of Gs and protein kinase A, which phosphorylates the M-type channel to increase its activity. E) Adenylyl cyclase-mediated production of M-type channel activator muscarine.

40. Which of the following molecules are considered second messengers of GPCR/G-protein signaling?

A) Ca2+, cAMP and IP3

B) GTP, phospholipase C, and adenylyl cyclase C) Protein kinases A and C.

D) PIP2, G protein subunits.

E) Ion channels such as Cav1, Cav2 and GIRK.

41. The G protein trimeric complex responsible for direct modulation of phospholipase C is...

A) Gq.

B) Gs.

C) Gi.

D) Go.

E) All of the G proteins modulate the phospholipase C enzyme.

42. Amino acid neurotransmitters include...

A) Dopamine, serotonin, norepinephrine and histamine. B) Acetylcholine, dopamine, norepinephrine and glycine. C) Glutamate, GABA and glycine.

D) ATP and other nucleotides.

E) Muscarine, nicotine and acetylcholine.

43. What kind of receptors do nicotine and muscarine activate in the central nervous system, respectively?

A) Acetylcholine G protein coupled receptors, acetylcholine ionotropic cys-loop receptors.

B) Acetylcholine ionotropic cys-loop receptors, acetylcholine G protein coupled receptors.

C) Adrenergic G protein coupled receptors, adrenergic ionotropic cys-loop receptors.

D) Adrenergic ionotropic cys-loop receptors, adrenergic G protein coupled receptors.

E) Dopaminergic G protein coupled receptors, dopaminergic ionotropic cys-loop receptors.

44. In the brain, cholinergic neurons tend to...

A) Increase the excitability of inhibitory neural circuits (e.g. GABAergic and glycinergic).

B) Decrease the excitability of inhibitory neural circuits (e.g. GABAergic and glycinergic).

C) Increase the excitability of excitatory glutamatergic neural circuits to increase attention and memory.

D) Decrease the excitability of excitatory glutamatergic neural circuits to increase attention and memory.

E) Exclusively secrete acetylcholine into synaptic clefts for detection by post-synaptic G protein coupled receptors.

45. Volume transmission...

A) Refers to the volume of neurotransmitter contained within one pre-synaptic vesicle (i.e. one quantum).

B) Is akin to local hormone signaling, where neurotransmitters are secreted into localized areas in the brain to affect synapses in the local vicinity.

C) Involves secretion of a neurotransmitter across the synaptic cleft, to directly activate post-synaptic receptors on the other side of the cleft.

D) Is exclusively used for pre-synaptic auto-inhibition.

E) All of the above statements are true.

46. In vertebrate cardiomyocytes, application of norepinephrine leads to...

A) Activation of the Gq pathway and protein kinase C, which phosphorylates Cav1 type calcium channels increasing their activity, leading to stronger contraction.

B) Activation of the Gs pathway and protein kinase A, which phosphorylates Cav1 type calcium channels increasing their activity, leading to stronger contraction.

C) Membrane-delimited inhibition of Cav1 channels via a G pathway, leading to weaker contraction.

D) Inhibition of HCN channels via inhibition of the adenylyl cyclase enzyme and a depletion of cAMP.

E) None of the above answers are true.

47. Mapping neurotransmitter systems in the CNS using marker genes...

A) Can be achieved by localizing expressed mRNAs or proteins of genes that are uniquely expressed in a specific neuron type (e.g. cholinergic neurons).

B) Provides useful information about where in the brain certain neurotransmitter systems types are located.

C) Often employs genes that are involved in neurotransmitter biosynthesis or transport.

D) Can identify nuclei within the brain where the cell bodies of a particular neuron-type are localized.

E) All of the above answers are correct.

48. Metabotropic G protein-coupled receptors in the brain that are activated by GABA...

A) Are called GABAA receptors.

B) Form a heterodimer, where each subunit can directly detect the ligand GABA and activate cytoplasmic G proteins.

C) Are typically associated with decreasing excitation of neurons.

D) Are directly responsible for inhibitory post-synaptic currents/potentials in neurons.

E) Show increased activity when agonists such as benzodiazepines are applied.

49. With respect to histaminergic synaptic transmission in the vertebrate brain...

A) Histamine only acts through the Gs and Gq G protein pathways.

B) A central nervous system histaminergic marker gene is tyrosine hydroxylase.

C) Histaminergic neuron bodies are located in the tuberomammilary nucleus in the brain.

D) Is a form of amino acid-based synaptic transmission.

E) Occurs exclusively via direct chemical synaptic transmission (i.e. as opposed to volume transmission).

50. Which of the following statements about dopamine in the vertebrate central nervous system is false?

A) Dopamine activates cationic cys-loop channels called 5-HT3 receptors.

B) Part of the dopamine biosynthesis pathway involves hydrolysis of tyrosine to by the serotonergic marker gene tyrosine hydroxylase.

C) Cell death of dopaminergic neurons in the substantia nigra is associated with Parkinson's disease.

D) Dopamine is mostly secreted via volume transmission in the brain.

E) Dopaminergic GPCR signaling in the nucleus accumbens is associated with drug addiction.