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Biophysics MCQs PMU 1st YR/2nd Sem

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Biophysics mcqs
Med Student
Quiz by Med Student , updated more than 1 year ago
Med Student
Created by Med Student over 8 years ago
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Resource summary

Question 1

Question
Action potential of neurons is mainly a result of
Answer
  • Na and K
  • Na and Mg
  • Ca and K

Question 2

Question
Strength of ion currents during action potential is related to
Answer
  • Duration of hyperpolarisation action potential phase
  • Equilibrium potentials of ions
  • Distance from point of stimulation

Question 3

Question
During action potential which quantity is altered
Answer
  • Permeability of membrane for diffusion types of ions
  • Diametric permeability of membrane
  • None

Question 4

Question
Membrane potential operated channels are on
Answer
  • active fixed value
  • permanently active
  • active in certain range in membrane potential

Question 5

Question
Mark correct
Answer
  • all the ion channels
  • all the ion channels let pass
  • ion flow depends on ion type and membrane potential

Question 6

Question
Ion channel blockers
Answer
  • Universal
  • Specific to given channels
  • Chemical substances attached to the channel during action potential

Question 7

Question
Ion channels are filled with
Answer
  • water
  • air
  • lipid

Question 8

Question
Action potential is
Answer
  • alteration of electric polarity of the membrane when cell moves
  • membrane response to over-threshold irritation
  • nonelectric quantity with chemical nature

Question 9

Question
At physiological condition cell membrane is
Answer
  • solid structure
  • gas
  • liquid-crystal structure

Question 10

Question
Membrane hyperpolarization leads to
Answer
  • elevation of the membrane potential
  • decrease of the membranes potential
  • alteration of membrane charge sign

Question 11

Question
Membrane depolarization leads to
Answer
  • Elevation of membrane potential
  • Decrease of membrane potential
  • Noe

Question 12

Question
Resting potential of cell membrane is measured in
Answer
  • Megavolts
  • Volts (v)
  • Millavolts (mv)

Question 13

Question
Action potential duration ten times of
Answer
  • seconds
  • milliseconds
  • nanoseconds

Question 14

Question
Which term is not related to action potential
Answer
  • Overshoot
  • Entropy
  • Depolarisation
  • Threshold

Question 15

Question
During the action potential
Answer
  • cation currents from intercellular to extracellular
  • cation currents from extracellular to intercellular
  • none of above

Question 16

Question
The first law or principle of thermodynamics(TD) is defined for
Answer
  • covered TD system
  • closed TD system
  • opened TD system

Question 17

Question
The ionophores are
Answer
  • ions used in medicine
  • transport molecules
  • ions after the ion polarisation

Question 18

Question
Blocking of Na/K pump working non-electrogenous in stage
Answer
  • make depolarization of cell membrane
  • make hyperpolarisation of cell membrane
  • make no alteration of cell membrane

Question 19

Question
The administration of the blocker tetradotoxin led to alteration of following stage of action potential
Answer
  • repolarisation phase
  • shape and type of trace potentials
  • depolarisation phase

Question 20

Question
Electrochemical potential is measured by
Answer
  • direct method with non polarized electrodes
  • by the disperse phase velocity in constant electric field
  • direct method- electrophoresis with constant electric field

Question 21

Question
In Boltzmann equation
Answer
  • entropy is directly proportional to the temperature
  • entropy logarithmically depends on the thermodynamic probability
  • entropy is directly proportional to the thermodynamical probability

Question 22

Question
The filaments of muscles are based on
Answer
  • actin fibers
  • troponin globules
  • myosin fibers

Question 23

Question
In cell membranes are present
Answer
  • hydrophobic interactions omly
  • hydrophilic interactions only
  • both types

Question 24

Question
The basic condition for arising of membrane potential
Answer
  • difference of ion concentration on the two sides of them
  • difference of temperature concentration on two sides of the membranes
  • "one way" permeability of the membrane

Question 25

Question
The classic electrophoresis is performed by
Answer
  • a constant current
  • alternated current
  • magnetic field

Question 26

Question
Smooth muscles are two types
Answer
  • phasic and tonic
  • tonic and synergic
  • phasic and antagonistic

Question 27

Question
In smooth muscle
Answer
  • Only phosphorylated myosin can bind to actin
  • Ca2+ calmodulin causes phosphorylation of myosin light chain kinase(MLCK)
  • Phosphorylated MLCK causes phosphorylation of myosin
  • A, B and C
  • None of the above

Question 28

Question
Each globular head group (often called a crossbridge) of a myosin molecule of skeletal muscle contains:
Answer
  • A binding site for the attachment of troponin
  • A binding site for the attachment of tropomyosin
  • An actin binding site and a myosin ATPase site
  • One site which binds troponin and another which binds tropomyosin
  • A site which is phosphorylated by protein kinase A(PKA), thereby allowing interaction with actin

Question 29

Question
In order to make ATP (adenosine triphophate) in muscles, creatine phosphate (CP) transfers ________________ to adenosine diphosphate (ADP)
Answer
  • Oxygen
  • Phosphate
  • Adenosine

Question 30

Question
A sacromere is part of a
Answer
  • Myofibril
  • Myofilament
  • Endomysium
  • Perimysium

Question 31

Question
Differences between striated (skeletal, cardiac) muscle and unstriated (smooth) muscle include:
Answer
  • only unstriated muscle is innervated by autonomic nervous system
  • only striated muscle exhibits pacemaker activity
  • striated muscle can contract in the absence of extracellular Ca2+, but unstriated muscle cannot
  • only unstratied muscle has gap junctions
  • none of the above are true

Question 32

Question
As a skeletal muscle contracts
Answer
  • The A bands become shorter
  • The I band become shorter
  • Adjacent Z lines become farther apart
  • The H zones don't change in size
  • The M lines become shorter

Question 33

Question
The period of contraction of a typical ventricular muscle fiber is
Answer
  • about the same as that of a typical slow skeletal muscle fiber
  • shorter than that of a typical atrial muscle fiber
  • slightly longer in duration than the action potential in the ventricular fiber
  • slightly shorter in duration than the action potential in the ventricular fiber
  • longer in duration than contraction in any smooth muscle cell

Question 34

Question
The transverse tubular system of skeletal muscle
Answer
  • has a very small lumenal volume and large surface area relative to the cytoplasmic volume and surface area of the fiber
  • propogates action potentials at about the same speed as the surface membrane
  • forms gap junctions with the sacroplasmic reticulum (SR)
  • never comes closer than about 1 micron from the SR membrane
  • does not contain voltage-gated Na+ channels

Question 35

Question
During the plateau (phase 2) of the ventricular action potential
Answer
  • Na+ channels remain open causing the continued depolarization
  • Ca2+ channels are mostly closed
  • K+ permeability of the membrane is greater than when the membrane is at rest
  • Both Ca2+ and K+ permeability of the membrane is lower than when the membrane is at rest
  • none of these

Question 36

Question
Contractility (or inotropic state) of cardiac muscle is increased by
Answer
  • increased stretch of cardiac muscle (e.g increased filling of the heart)
  • increased myoplasmic Ca2+ during systole
  • Ca2+ channel blockers
  • Decreased coronary blood supply
  • Both A and B will increase contractility

Question 37

Question
The sequence for smooth muscle contraction is....
Answer
  • increased 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
  • increased cytosolic calcium, which binds to calmodulin in cytosol, which binds with myosin cross-bridges resulting in contraction
  • increased 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
  • increase cytosolic calcium, which binds to troponin, which moves tropomyosin from blocking active actin filament, which binds with myosin cross-bridges resulting to contraction

Question 38

Question
The neuron action potential starts with
Answer
  • Na+ influx
  • Na+ eflux
  • N+ influx

Question 39

Question
The membrane potential after accessing its maximal valve by constant condition
Answer
  • Remain stable in time
  • Decrease exponentially
  • Slowly close resting membrane potential

Question 40

Question
The trans-membrane proteins in difference with peripheral
Answer
  • do transversal diffusion
  • have hydrophilic and hydrophobic parts
  • possess mainly enzymes activity

Question 41

Question
The most punctual definition of membrane potential valve is defined with the equation of
Answer
  • Goldman
  • Nernst
  • Bernstein

Question 42

Question
Sodium-potassium pump in electrogenic condition
Answer
  • depolarized cell membrane
  • repolarized cell membrane
  • hyperpolarized cell membrane

Question 43

Question
TTX tetrodoxin is a blocker of
Answer
  • potassium channels
  • sodium channels
  • calcium channels

Question 44

Question
The contraction of striated muscle
Answer
  • faster than smooth muscle
  • slower than smooth muscle
  • equal to smooth muscle

Question 45

Question
Thin filaments of muscle
Answer
  • Actin fibers
  • Troponin
  • Myosin fibers

Question 46

Question
Striated muscles are characterized
Answer
  • perodically alter
  • equal to zero membrane potential
  • stable resting

Question 47

Question
Source of calcium needed for contraction striated muscle (rapid transition)
Answer
  • Extracellular
  • Endoplasmic Reticulum
  • Motor Neurons

Question 48

Question
Hyperpolarisation phase of striated muscles
Answer
  • Preliminary to the stiulus
  • Repeats twice after each action potential occurs
  • Is missing

Question 49

Question
Mark the correct expression
Answer
  • all ion channels let pass ions from extra to intra cellular compartment
  • all ion channels let pass ions from intra to intra cellular compartment
  • ion flow depends on ion type and membrane potential

Question 50

Question
The 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
Answer
  • True
  • False

Question 51

Question
Source of calcium needed for contraction striated muscle tissue (rapid transition) is
Answer
  • Extracellular
  • Endoplasmic Reticulum
  • Motor Neurons

Question 52

Question
Contraction of smooth muscle is _____________ than that of skeletal muscle
Answer
  • slower
  • faster
  • equal

Question 53

Question
The trans-membrane transport (transdiffusion) is similar to
Answer
  • A filtration
  • A passive membrane transport
  • An active membrane transport

Question 54

Question
Smooth muscle's slow wave is defined by
Answer
  • Concentration of Na+, K+ and Ca2+
  • Concentrations of Na+, K+ and Ca2+ pump
  • Concentrations of Na+, K+ and Na/K pump

Question 55

Question
Order the polarizations according to their time of appearing
Answer
  • Ionic, Dipolar, Macrostructural
  • Surface, Dipolar, Ionic
  • Surface, Macrostructural, Dipolar

Question 56

Question
The membrane potential after reaching maximum value
Answer
  • Remains constant in time
  • Is altered slowly to submaximal value
  • Decreases to zero

Question 57

Question
The membrane lipids are
Answer
  • amphiphilic
  • formed glycocalcs
  • have many transport function

Question 58

Question
The lipids are
Answer
  • transmembrane
  • membrane receptor
  • organized in layers

Question 59

Question
The plateau phase of myocardial cells is determined by
Answer
  • Concentrations of Ca2+ and Na+
  • Concentrations of Ca2+ and K+
  • Concentrations of Na

Question 60

Question
Membrane potential depends on
Answer
  • temparature of the thermodynamic system
  • viscosity of the medium
  • medium's protein/lipid ration
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