Biofysikk Ingvild Januar 2006
Multiple choice questions 1 semester in Biophysics
Only question and the right answer!
The photoelectric effect (as the interaction of X-rays with the matter) causes:
-the ionization of the atom
Characteristic X-rays are generated
-in the innermost shell of an atom
X-rays have
-a superposition of a continuous spectrum and a line spectrum
As described by the Bohr’s model the energy of an electron orbiting in a given shell
-is inversely proportional to the square of the principal quantum number n
The vibrational energy transitions of a molecule are within the range of
-infrared rays
The mass number of a radioactive atom
-decreases by 4 in case of alpha decay
The specific ionization of an alpha radiation
-is the greatest just before the particles stop
The intensity of a nuclear gamma radiation decreases about to the 1000th of the intensity of the incident radiation, when the radiation penetrated the absorber in a depth which is
-the decrease is independent of the depth of penetration
The pair-production requires a photon-energy of
-1,02 MeV at least
The correct form of the radioactive decay law is
-N = N02 – t/T eller e sjekk ut!
To record an ESR spectrum, we have to
-put the sample in an electromagnetic wave field superimposed on an homogenous magnetic field
According to Moseley`s law
-the square root of the wave number is linearly proportional to the atomic number
The energy of an electron orbiting in the atom, according to the Bohr’s model
-inversely proportional to the square of the principal quantum number n of the orbit
The most obvious evidence of the wave nature of the light is
-the interference
Gamma radiation
-is an electromagnetic wave generated in the atomic nucleus
The intervention of a gamma photon is a photo effect, when the gamma photon interacts with
-an electron of the innermost shell
The most informative part of a molecular spectrum referring to the strength of chemical bonds is
-the vibration spectrum
The (optical) extinction
-is the logarithms of the ratio of the intensity of the incident light and the intensity
Characteristic X-rays are
-electromagnetic waves
The characteristic spectrum of X-rays is
-determined by the material of the anode
The work function of the photoelectric phenomenon is not
-proportional to the intensity of the incident light
-inversely proportional to the frequency of the incident light
-inversely proportional to the intensity of the incident light
The atomic number aftera positive beta decay
-decreases by one
The frequency of the light scattered by molecules
-may be smaller or greater than the frequency of the incident light
What is the photoelectric effect?
-some materials (e.g. alkali metals, some metal oxides) emit electrons under the effect of illumination by visible light
A consequence of the De Broglie formula that
- the wavelength of an electron is inversely proportional to its speed
X-rays are exclusively different from other electromagnetic waves because
- They are generated in the electronic shells
The degree of absorption of X-rays does not depend on
-the time duration of the experiment
The degree of absorption of X-rays does depend on
-the kind of the absorber
-the scattering of X-rays
-the wavelength of X-rays
-the thickness of the target
The value of the Planck constant may be determined
-by a photoelectric experiment
Which thermodynamic quantity is not a state function?
-entropy
The thermodynamic quantity state functions
-enthalpy
-Gibb’s free energy
-internal energy
-heat exchange of a system
The particles produced during pair production are
-photon and neutron
If the accelerating increases, the cut off-wavelength of the generated X-rays
-decreases
According to de Bogie’s matter wave theory a wave can be assigned to any moving particle, the wavelength of which is
-inversely proportional to the momentum of the particle
Following irradiation the fraction of surviving organisms
-decreases exponentially with increasing rate
During equalization of concentration difference the diffusion constant
-decreases to zero
In the photoelectric effect the number of the electrons emitted from the illuminated metal surface depend on
-the intensity of light
What is the frequency of light the wavelength of which is 500 nm (the speed of light is 3x108 m/s)?
-6 x 105 Hz
The total number of electronic states for a given principal quantum number n is
-2n2
X-rays differ from visible light in that
- its wavelength is longer
Diffusion is driven by
-the chemical interactions between the particles
Characteristic X-ray radiation
-is the result of gradual deceleration of electrons
During the emission of β (-) radiation the mass number
-increases by one
What is the relationship between the rate constant of the radioactive decay and half-life?
-they are not related to each other
In the physical and biological half-lives of a radioactive material are both 1 day, then the effective half-life is
-2 days
The effective half-life of a radioactive substance
-is practically the same as the biological half-life in case of very long physical half-life
β (-) radiation consists of
- Positrons… usikker på denne
The Compton Effect is
-ejection of electrons from the surface of an illuminated metal
Based on the D37 one can determine
-the volume of the radiosensitive site
Which quantity is not extensive?
-Volume
Which quantities are extensive?
-mass
-temperature
-internal energy
-entropy
Which statement applies to a reversible process?
-the work done by the system is the greatest
Thermodynamic probability
-is inversely proportional to mathematical probability
Example of the application of thermo diffusion
-separation of compounds with different molecular weight
During equalization of concentration differences the diffusion constant
-decreases to zero
In the photoelectric effect the number of electrons emitted from the illuminated metal surface depend on
-the frequency of light
-the wavelength of light
-the intensity of light
The total energy emitted by a black body at a given T temperature
-
The radius of an atom is approximately
-
The effective half-life of a radioactive substance
-
Following irradiation of surviving organisms
-
What type of thermodynamic system is the living organism?
-
Audible sound
-
According to Békésy’s theory, frequency recognition is based on
-
When the accelerating potential difference in an X-ray tube decreases, the limiting wavelength
-will increase
The α-radiation
-has a range proportional to its energy
The most informative part of a molecular spectrum referring to the strength of chemical bonds is
-the vibration spectrum
The main function of the sodium-potassium ATPase is
-to pump sodium ions out and potassium ions into the cell
The action potential
-is a consequence of a quick change in the ion permeability
The rods in the retina
-form receptor fields on the periphery of the retina
The osmosis
-is characterised by the gauge pressure in isotherm steady state conditions
The diffusion coefficient
-depends on the temperature
The equilibrium osmotic pressure does not depend on
-the elapsed time
The retinal
-is a carotenoid molecule
-has two stereoisomers configuration
-has alternate double bounds in its stereoisomer configuration
-undergoes a conformation change after absorption of a single photon
The receptor potential
-has an amplitude that depends on the stimulus intensity
According to Bernoulli’s law, the static pressure
-is increasing if the cross section area of the flow tube is increasing
The Gibb’s free energy
-determines the direction of the spontaneous processes on its own
The ciliary’s muscle (muscular ciliary’s)
-influences the dioptre of the eye lens
The Reynolds number
-below its critical value the flow is laminar
The work done by the heart
-is approximately equal to the work done by a motor with output of 1 Watt
Diffusion is generated
-due to the Brownian motion of the particles
The cross striated muscle
-has a I-band the length of which decreases during shortening
Donnan equilibrium can be estimated between two compartments separated by a membrane if
-the membrane is permeable for small ions but not permeable for charged macromolecules
During osmosis
-the more concentrated solution becomes diluted
Diffusion is driven by
-the random thermal motion of molecules
The equilibrium of which parameter between the two compartments indicates the onset of the osmotic equilibrium
-the chemical potential of the solvent
Red blood cells are placed in isotonic, hypotonic and hypertonic solutions. Which relationship is true for the volume of red blood cells?
-> hypotonic> isotonic > hypertonic
Newtonian fluids
-viscosity does not depend on the shear stress
According to Bernoulli law the static pressure
-increases when the diameter of the flow canal increases
When the Reynolds number exceeds to the critical value?
-the fluid flow becomes turbulent
Which law can explain the formation of the aneurism?
-Bernoulli’s law
Apparent blood viscosity depends on
-diameter of blood vessels
-plasma viscosity
-hematocrit value
The value of blood pressure
-changes periodically
In which segment of the vascular system is the blood pressure the highest?
-Aorta
When the heart rate increases
-the duration of the diastole decreases
In the work of the heart
-the volumetric component dominates
What type of interaction acts between water molecules in liquid water?
-hydrogen bonds
What parameters are plotted on the phase diagram of water?
-pressure – temperature
How many H-bonds does a water molecule participate in ordinary ice?
-4
The shape of a random polymer chain depends on
-its bending rigidity
The shape of a polymer chain free of interactions resembles
-the path of a particle performing random motion
The protein molecule can be unfolded by
-heat
-chemical effects
-mechanical force
Which bond type has a role in the formation of the tertiary structure of proteins?
-disulphide bridges
-hydrogen bonds
-salt bridges
-hydrophobic interactions
How can transmembrane proteins be extracted from a membrane
-by using detergents
What type of interaction holds the neighbouring lipid molecules together in a lipid bilayer or a micelle?
-hydrophobic interactions
Voltage gated Na+ channels
-open when the membrane is depolarized
When the stimulus intensity increases
-the amplitude of the receptor potential increases
A single neuron can have
- even hundreds of synapses
The positron emission tomography
-detects the active part of the central nervous system
The decay rate n a radioactive sample depends on
-number of undecayed atoms
To record an ESR spectrum, we have to
-put the sample in an electromagnetic wave field superimposed on a homogenous electric field
The anisotropy of the steady state fluorescence emission depends on
-the actual volume of the fluorescent dye
Photeselection
-excites an oriented fraction of the population of molecules
In a centrifuge
-particles may be separated only, if they have a mass density different from the mass density of the suspending medium
The Förster resonance transfer is a phenomenon, in which
-The energy of an exited state is transmitted by a dipole-dipole interaction
Stimulated emission
-produces a light wave that is in phase with the inducing light
The optical extinction
-the logarithm of the ratio of the intensity of the incident light and the intensity of the light at a distance x within a translucent object
The most informative part of a molecular spectrum referring to the strength of chemical bonds is
-the vibration spectrum
The spectrum of an organic compound (as a protein) may be
-absorption, band spectrum
When the accelerating potential in an x-ray tube decreases, the limiting wavelength
-will increase
Multiple comparisons
The absorbtivity (absorption ability) of a blackbody is high, because its emissivity (emission ability) is low
-
The electron microscope’s resolving power is greater than that of the optical microscope because the wavelength associated with the electron beam used in the electron microscope is much greater than the wavelength of visible light
- first is true
Light emitted by glowing He-gas has continuous spectrum, because light emission occurs according to Bohr’s second postulate
-
The speed of propagation of X-ray is greater than that of visible light because the frequency of X-ray is greater than that of visible light
-
The decay rate of a radioactive sample cannot be influenced, because the radioactive decay probability is not sensitive to external conditions
-
The periodic character of the current-voltage curve of the Franck-Hertz experiment disappears with increasing voltage, because the electrons removed from the atom by ionization have a n energy that is not quantized
- first is false, second is trueD
The energy emitted by a “black body” is proportional to the fourth power of the absolute temperature, because the energy of an electronic orbit is proportional to the second power of its radius
- first is true, second is falseC
The smaller the principal quantum number of an orbit, the smaller the binding energy of an electron, because binding energy is defined as the amount of energy required to remove an electron from the atom
- fist is false, second is trueD
The energy of an X-ray photon is limited by the electric potential difference across the X-ray tube, because the kinetic energy of the electrons is converted into photon-energy
- both are true, second explains the firstA
The X-ray spectrum has a typical limiting wavelength at a given accelerating voltage because the average efficiency of the energy conversion in an X-ray tube is 1 per cent
- both are true, second does not explain the firstB
The energy of an X-ray photon may be calculated as hv=eUbecause this calculation is accordance with the law of the conservations
- both are true, second does explain the firstA
The number of (photo) electrons ejected from an illuminating metal plate is proportional to the intensity of the induced light because the photoelectric effect has a threshold (cut off) frequency below which no photoelectrons released from the material
- both are true, second does not explain the first B
The emittivity of an absolute black body is greater than that of any other object because a black body perfectly absorbs the incident radiation of any wavelength
- first is false, second is trueD
An electron-positron pair are created every time when a gamma photon interacts with a target, because the an inhibition process results in generating gamma radiation
- first is false, second is trueD
The relative intensity of a light travelling in a medium depends on the distance covered because the decrease of the intensity is described by the equation: -dI=kI.dx
-both are true, second explains first A
An electron is removed from a metal with a greater velocity by ultraviolet radiation, then by red light, because ultraviolet radiation warms up the metal
-both are true, second does not explain the firstB
The wavelength and the intensity of X-rays can be controlled in an independent way because wavelength depends on the potential difference across the x-ray tube
- first is true, second is falseC
When generating X-rays, the emission of a photon of the characteristic radiation is always preceded by the emission of a “bremsstrahlung” because only slow electrons can interact with electrons of the innermost orbits
- both are falseE
The probability of the radioactive decay decreases with time, because the number of undecayed atoms decreases
- first is false, second is trueD
The wavelength of a particle (called “de Broglie” wavelength) increases with increasing the speed of the particles because photons both have wave and particle characteristics
- first is false, second is trueD
A sodium channel in the membrane may be opened by a depolarizing potential because it is a voltage gated channel
- both is true, second explains firstA
The penetration depth of a α particles is shorter than that of β particles, because α particles have shorter wavelength
- first is true, second is false C
Equal physical doses of ay nuclear radiation result in the same biological effect because the biological effect is closely related to the specific ionization
- first is false, second is trueD
The work done by the heart is smaller during hard physical exercise, than that at rest, because physical exercise results in a constriction of veins
- both are false E
The information content of a result is inversely proportional to the uncertainty belonging to the experiment, because the smallest unit of information is one bit
- both are true, but first does not explain secondB
The viscosity of the water is dependent on the temperature because water viscosity increases with increasing temperature
- first is true, second is falseC
The average lifetime of fluorescence is 1 to 100 ns because any exited state can be exited (relaxed) with or without photon radiation
- both is true, first does not explain the secondB
The imaging of a human eye may be modelled by a single lens, because the simple optical model of the human eye has six cardinal points
- first is true, second is falseC
Diffusion occurs only within gases and liquids because the particles of solids vibrates only
- both is false E
Spontaneous reactions proceed in a direction so that the changes in G or F are negative, because G and F are state functions and they depend only on the state of the system
- both is true, first does not explain the first oneB
4 0C is a biologically prominent temperature because the density of water is the greatest at this temperature
- both are true, second explains the firstA
The focal length of the eye lens can be increased by decreasing its radius of curvature (by the action of ciliary’s muscles), because the index of refraction of the other focal-length-affecting component, the vitreous humour relative so that of the air is constant, and its value is 0,2
-both are falseE
The sarcomere is the smallest functional unit of muscle, because skeletal muscle consist of striated muscle
- both are trueA or B…?
The human eye is sensitive only to photons, because the photoreceptors are located next to the choroids membrane therefore the photons must traverse the entire thickness of the retina to reach the cones and rods
- first is false, second is trueD
During the change of action potential the permeability to both Na+ and K+ ions changes, because action potential is accompanied in membrane structure
- first is true, second is falseC
The velocity of blood flow is the aorta is much smaller than in a capillary, because the cross sectional area of a capillary is much smaller than that of the aorta