Test
Biophysics MCQs PMU 1st YR/2nd Sem
Preguntas del test (60)
1Action potential of neurons is mainly a result of
- ANa and K
- BNa and Mg
- CCa and K
2Strength of ion currents during action potential is related to
- ADuration of hyperpolarisation action potential phase
- BEquilibrium potentials of ions
- CDistance from point of stimulation
3During action potential which quantity is altered
- APermeability of membrane for diffusion types of ions
- BDiametric permeability of membrane
- CNone
4Membrane potential operated channels are on
- Aactive fixed value
- Bpermanently active
- Cactive in certain range in membrane potential
5Mark correct
- Aall the ion channels
- Ball the ion channels let pass
- Cion flow depends on ion type and membrane potential
6Ion channel blockers
- AUniversal
- BSpecific to given channels
- CChemical substances attached to the channel during action potential
7Ion channels are filled with
- Awater
- Bair
- Clipid
8Action potential is
- Aalteration of electric polarity of the membrane when cell moves
- Bmembrane response to over-threshold irritation
- Cnonelectric quantity with chemical nature
9At physiological condition cell membrane is
- Asolid structure
- Bgas
- Cliquid-crystal structure
10Membrane hyperpolarization leads to
- Aelevation of the membrane potential
- Bdecrease of the membranes potential
- Calteration of membrane charge sign
11Membrane depolarization leads to
- AElevation of membrane potential
- BDecrease of membrane potential
- CNoe
12Resting potential of cell membrane is measured in
- AMegavolts
- BVolts (v)
- CMillavolts (mv)
13Action potential duration ten times of
- Aseconds
- Bmilliseconds
- Cnanoseconds
14Which term is not related to action potential
- AOvershoot
- BEntropy
- CDepolarisation
- DThreshold
15During the action potential
- Acation currents from intercellular to extracellular
- Bcation currents from extracellular to intercellular
- Cnone of above
16The first law or principle of thermodynamics(TD) is defined for
- Acovered TD system
- Bclosed TD system
- Copened TD system
17The ionophores are
- Aions used in medicine
- Btransport molecules
- Cions after the ion polarisation
18Blocking of Na/K pump working non-electrogenous in stage
- Amake depolarization of cell membrane
- Bmake hyperpolarisation of cell membrane
- Cmake no alteration of cell membrane
19The administration of the blocker tetradotoxin led to alteration of following stage of action potential
- Arepolarisation phase
- Bshape and type of trace potentials
- Cdepolarisation phase
20Electrochemical potential is measured by
- Adirect method with non polarized electrodes
- Bby the disperse phase velocity in constant electric field
- Cdirect method- electrophoresis with constant electric field
21In Boltzmann equation
- Aentropy is directly proportional to the temperature
- Bentropy logarithmically depends on the thermodynamic probability
- Centropy is directly proportional to the thermodynamical probability
22The filaments of muscles are based on
- Aactin fibers
- Btroponin globules
- Cmyosin fibers
23In cell membranes are present
- Ahydrophobic interactions omly
- Bhydrophilic interactions only
- Cboth types
24The basic condition for arising of membrane potential
- Adifference of ion concentration on the two sides of them
- Bdifference of temperature concentration on two sides of the membranes
- C"one way" permeability of the membrane
25The classic electrophoresis is performed by
- Aa constant current
- Balternated current
- Cmagnetic field
26Smooth muscles are two types
- Aphasic and tonic
- Btonic and synergic
- Cphasic and antagonistic
27In smooth muscle
- AOnly phosphorylated myosin can bind to actin
- BCa2+ calmodulin causes phosphorylation of myosin light chain kinase(MLCK)
- CPhosphorylated MLCK causes phosphorylation of myosin
- DA, B and C
- ENone of the above
28Each globular head group (often called a crossbridge) of a myosin molecule of skeletal muscle contains:
- AA binding site for the attachment of troponin
- BA binding site for the attachment of tropomyosin
- CAn actin binding site and a myosin ATPase site
- DOne site which binds troponin and another which binds tropomyosin
- EA site which is phosphorylated by protein kinase A(PKA), thereby allowing interaction with actin
29In order to make ATP (adenosine triphophate) in muscles, creatine phosphate (CP) transfers ________________ to adenosine diphosphate (ADP)
- AOxygen
- BPhosphate
- CAdenosine
30A sacromere is part of a
- AMyofibril
- BMyofilament
- CEndomysium
- DPerimysium
31Differences between striated (skeletal, cardiac) muscle and unstriated (smooth) muscle include:
- Aonly unstriated muscle is innervated by autonomic nervous system
- Bonly striated muscle exhibits pacemaker activity
- Cstriated muscle can contract in the absence of extracellular Ca2+, but unstriated muscle cannot
- Donly unstratied muscle has gap junctions
- Enone of the above are true
32As a skeletal muscle contracts
- AThe A bands become shorter
- BThe I band become shorter
- CAdjacent Z lines become farther apart
- DThe H zones don't change in size
- EThe M lines become shorter
33The period of contraction of a typical ventricular muscle fiber is
- Aabout the same as that of a typical slow skeletal muscle fiber
- Bshorter than that of a typical atrial muscle fiber
- Cslightly longer in duration than the action potential in the ventricular fiber
- Dslightly shorter in duration than the action potential in the ventricular fiber
- Elonger in duration than contraction in any smooth muscle cell
34The transverse tubular system of skeletal muscle
- Ahas a very small lumenal volume and large surface area relative to the cytoplasmic volume and surface area of the fiber
- Bpropogates action potentials at about the same speed as the surface membrane
- Cforms gap junctions with the sacroplasmic reticulum (SR)
- Dnever comes closer than about 1 micron from the SR membrane
- Edoes not contain voltage-gated Na+ channels
35During the plateau (phase 2) of the ventricular action potential
- ANa+ channels remain open causing the continued depolarization
- BCa2+ channels are mostly closed
- CK+ permeability of the membrane is greater than when the membrane is at rest
- DBoth Ca2+ and K+ permeability of the membrane is lower than when the membrane is at rest
- Enone of these
36Contractility (or inotropic state) of cardiac muscle is increased by
- Aincreased stretch of cardiac muscle (e.g increased filling of the heart)
- Bincreased myoplasmic Ca2+ during systole
- CCa2+ channel blockers
- DDecreased coronary blood supply
- EBoth A and B will increase contractility
37The sequence for smooth muscle contraction is....
- Aincreased cytosolic calcium, which binds to troponin, complex binds with myosin light-chain kinase which uses ATP to phosphorylate myosin cross-bridges, which bind to actin filaments, resulting in contraction
- Bincreased cytosolic calcium, which binds to calmodulin in cytosol, which binds with myosin cross-bridges resulting in contraction
- Cincreased cytosolic calcium, which binds to calmodulin in cytosol, which moves tromyosin from blocking active sites on actin filament, which binds with myosin cross-bridges, resulting in contraction
- Dincrease cytosolic calcium, which binds to troponin, which moves tropomyosin from blocking active actin filament, which binds with myosin cross-bridges resulting to contraction
38The neuron action potential starts with
- ANa+ influx
- BNa+ eflux
- CN+ influx
39The membrane potential after accessing its maximal valve by constant condition
- ARemain stable in time
- BDecrease exponentially
- CSlowly close resting membrane potential
40The trans-membrane proteins in difference with peripheral
- Ado transversal diffusion
- Bhave hydrophilic and hydrophobic parts
- Cpossess mainly enzymes activity
41The most punctual definition of membrane potential valve is defined with the equation of
- AGoldman
- BNernst
- CBernstein
42Sodium-potassium pump in electrogenic condition
- Adepolarized cell membrane
- Brepolarized cell membrane
- Chyperpolarized cell membrane
43TTX tetrodoxin is a blocker of
- Apotassium channels
- Bsodium channels
- Ccalcium channels
44The contraction of striated muscle
- Afaster than smooth muscle
- Bslower than smooth muscle
- Cequal to smooth muscle
45Thin filaments of muscle
- AActin fibers
- BTroponin
- CMyosin fibers
46Striated muscles are characterized
- Aperodically alter
- Bequal to zero membrane potential
- Cstable resting
47Source of calcium needed for contraction striated muscle (rapid transition)
- AExtracellular
- BEndoplasmic Reticulum
- CMotor Neurons
48Hyperpolarisation phase of striated muscles
- APreliminary to the stiulus
- BRepeats twice after each action potential occurs
- CIs missing
49Mark the correct expression
- Aall ion channels let pass ions from extra to intra cellular compartment
- Ball ion channels let pass ions from intra to intra cellular compartment
- Cion flow depends on ion type and membrane potential
50The membrane theory of excitation is based on the idea that stimulation of the surface membrane of an excitable cell causes a molecular restructuring that alters the membrane’s permeability and gives rise to transmembranous ion currents
- AVerdadero
- BFalso
51Source of calcium needed for contraction striated muscle tissue (rapid transition) is
- AExtracellular
- BEndoplasmic Reticulum
- CMotor Neurons
52Contraction of smooth muscle is _____________ than that of skeletal muscle
- Aslower
- Bfaster
- Cequal
53The trans-membrane transport (transdiffusion) is similar to
- AA filtration
- BA passive membrane transport
- CAn active membrane transport
54Smooth muscle's slow wave is defined by
- AConcentration of Na+, K+ and Ca2+
- BConcentrations of Na+, K+ and Ca2+ pump
- CConcentrations of Na+, K+ and Na/K pump
55Order the polarizations according to their time of appearing
- AIonic, Dipolar, Macrostructural
- BSurface, Dipolar, Ionic
- CSurface, Macrostructural, Dipolar
56The membrane potential after reaching maximum value
- ARemains constant in time
- BIs altered slowly to submaximal value
- CDecreases to zero
57The membrane lipids are
- Aamphiphilic
- Bformed glycocalcs
- Chave many transport function
58The lipids are
- Atransmembrane
- Bmembrane receptor
- Corganized in layers
59The plateau phase of myocardial cells is determined by
- AConcentrations of Ca2+ and Na+
- BConcentrations of Ca2+ and K+
- CConcentrations of Na
60Membrane potential depends on
- Atemparature of the thermodynamic system
- Bviscosity of the medium
- Cmedium's protein/lipid ration
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