問題一覧
1
The nerve impulse propagates with the highest speed in:
myelinated nerve fibers
2
What are the main factors that lead to the emergence of membrane potential?
selective membrane permeability and ion concentration gradient
3
The theory of indirect effect of radiation on bio-objects is based on:
radiolysis of water and action of its products on biomolecules
4
The impedance dispersion of bio-objects reflects:
vanishing of some polarization types with increasing frequency of the current
5
Interruption of the peroxidation chain reaction can be achieved by: (select one of a, b, c, d, e, f): A) metal ions with variable valency; B) recombination of free radicals; C) inhibitors
B and C are true
6
At same difference of ion concentration across a membrane, the value of which potential is higher:
they are the same
7
What are the main factors that lead to the emergence of membrane potential?
selective membrane permeability and ion concentration gradient
8
The dispersion of the impedance is:
dependence of the impedance on the frequency of the current
9
The passive electrical properties of bio-objects are:
resistance and capacitance
10
Electric double layer around the cells occurs due to: (select one of a, b, c, d, e, f): A) the presence of dissolved ions in the medium; B) the presence of the protein pumps for active transport into the cell membrane; C) the presence of surface charge of the cell.
A) and C)
11
The thick filaments in the sarcomere are made up from:
myosin
12
Whole-body impedance is a physical quantity, which characterizes organism from the point of view of itsability:
To conduct alternating electrical current
13
The protection of cells from free radical peroxidation includes:
enzymes, antioxidants, inhibitors of free radicals
14
The current-voltage characteristics of biological tissue is the graphic record of functional dependence=f(U). It expresses the actual ability to conduct direct electric current, which amount is in inverseproortion:
To its electric resistance
15
The singlet oxygen ¹O₂, has two electrons located:
on two separate orbitals having opposite spins
16
The double electric layer around the cells plays a role in: (select one of a, b, c, d, e, f): A) the generation of a transmembrane potential B) the stabilization of cell suspension C) Electrokinetic process
B) and C)
17
Zeta-potential is the value of the electric potential:Zeta-potential is the value of the electric potential:
in the slipping plane
18
The most susceptible to peroxidation are:
unsaturated fatty acid
19
Electric properties of the cell membranes - high resistance and capacitance are due to:
the lipid bilayer of the membrane
20
The quantity of Information in a message is higher if
the message reports about occurrence of an improbable event
21
The ion of which element is most important in muscle contraction?
calcium
22
The formation of free radicals can be achieved by:
homolysis, photolysis and radiolysis, single-electron transfer reaction with a suitable endogenous agent
23
The enzyme superoxide dismutase catalyzes:
dismutation of O2- to H2O2 and O2
24
The Target theory for the mechanism of the radiation effect on bio-objects is based on:
the existence of structures with increased radio-sensibility, their damage has a fatal effect
25
The repolarization of the membrane of excitable cells in caused by
passive transport of potassium ions
26
Electrokinetic phenomena are: (select one of a, b, c, d, e, f): A) electrolysis and electrofusion; B) phenomena occurring in dispersion systems due to the electric double layer at the interphase boundary between the dispersed phase and the dispersion medium; C) electrophoresis, electroosmosis, streaming potential and sedimentation potential.
B and C are true
27
The value of the action potential is most close to :
the equilibrium potential of Na⁺
28
Muscle contraction is due to:
Sliding of the actin and myosin filaments relative to each other due to a conformational change of the head of myosin, for which the energy of ATP is used.
29
The known types of dielectric permittivity dispersions in bio-objects ( α-,β-, γ-) are explained by:
Elimination of certain type of polarization of the object when the frequency of the current exceeds a relevant critical value , the sequential disappearance of the electronic, molecular, and orientational polarization of bio-objects when the frequency of the current increases.
30
During electromechanical coupling in muscle cells:
depolarization of the sarcolemma precedes muscle contraction
31
Phosphorescence occurs when the excited molecule pass:
from the triplet state to the ground state
32
Cybernetic systems are:
systems that use information to control their parameters according to a specific program
33
The sodium and potassium channels in the membrane of excitable tissues
open and close with the energy of ATP
34
The reactive oxygen species are:
harmful, because they oxidize and change biomacromolecules
35
The electric polarization of biological objects leads to change of:
the dielectric permittivity and the capacitance of the objects
36
The thin filaments in the sarcomere are made up mostly from:
actin
37
Action potential occurs in
excitable cells and tissues
38
The occurrence of electric polarization in biological objects is explained by:
displacement of their bound charges from their equilibrium position when bio-objects are placed in an external electric field
39
Nonenzymatic mechanisms for protection against free radicals include:
α - tocopherol and ascorbate
40
Photosensitizers enhance the effect of the visible light or UV-radiation as:
all of the above
41
The reactive forms of oxygen include: (OH.- hydroxyl radical; 1O2 - singlet oxygen; O2- superoxide anion radical; OH- - hydroxyl anion; O2 - oxygen; H2O2 - hydrogen peroxide; H2O - water; CO2 - carbon dioxide; CO - carbon oxide)
1O2, O2-., OH. and H2O2
42
K+/Na+ pump is presented?
In the plasmalemma of cell types
43
The surface electric charge is generated by:
dissociation of ionogenic surface groups
44
Cybernetic systems with negative feedback programs are
keeping their parameters constant at values given by the program
45
As the concentration of ions in the medium increases, the thickness of the diffusion layer of the double electric layer:
decreases
46
The following types of radiation are directly ionizing
α rays and β rays
47
The active resistance of the cell membranes is:
much higher than that the resistance of the cytoplasm
48
Which of the following membrane conditions activate the voltage-gated (potential-dependent) ion channels?
depolarization of the plasma membrane
49
Shannons model describes the principle of:
Transfer of information (communication)
50
During contraction muscle cells convert:
the chemical energy of ATP into mechanical work