Exam (single choice) Flashcards
In a brightfieldmicroscope, which component ensures that the illumination light is collected and guided onto the specimen?
a) Ocular lens
b) Field lens
c) Tube lens
d) Objective lens
e) Condenser lens
e) Condenser lens
In which type of microscopes is the birefringence (anisotropy) of a structure detected?
a) Epifluorescence microscope
b) Polarization microscope
c) Dark field microscope
d) Scanning electron microscope
e) Multiphoton microscope
b) Polarization microscope
Which principle do light microscopes use to form an image visible to the eye under ultraviolet illumination?
a) Phase shifts
b) Twophotonabsorption
c) Angular illumination
d) Fluorescence
e) A confocalpinhole
d) Fluorescence
How are field of view and resolution usually related in a microscopic image?
a) The larger the field of view, the greater the resolution.
b) The higher the resolution, the larger the microscope.
c) The larger the magnification of the objective, the smaller the field of view.
d) The larger the NA of the objective, the larger the field of view.
c) The larger the magnification of the objective, the smaller the field of view.
What physical laws govern photophysics?
a) Huygens principle
b) The quantization of all energy states as described by quantum mechanics
c) The three laws of thermodynamics
d) The conservation of momentum
b)The quantization of all energy states as described by quantum mechanics
What is the advantage of fluorescent dyes with a large Stokes shift?
a) Easier separation of excitation and fluorescence radiation
b) Higher resolution
c) Better contrast
d) Higher photostability of the dye
a) Easier separation of excitation and fluorescence radiation
What are common features of confocal microscopy (CM) and structured illumination microscopy (SIM).
a) Both reduce photodamage compared to classical microscopy
b) Both allow faster imaging speed than classical microscopy
c) Both have higher detection sensitivity than classical microscopy
d) Both increase resolution compared to classical microscopy
d) Both increase resolution compared to classical microscopy
What is called deconvolution in microscopy?
a) The enlargement of the image field by combining multiple microscopic images
b) The consideration of the effect of the point spread function (PSF) on imaging
c) The combination of images from different directions to improve the signal-to-noise ratio
d) The separation of phase from amplitude information in a microscopic image.
b) The consideration of the effect of the point spread function(PSF) on imaging
What mathematical transformation connects the light fields in the image and apertureplanes?
a) Fourier transform
b) Imaging equation
c) Hilbert transform
d) Sine transform
a) Fourier transform
Which statement about total internal reflection fluorescence microscopy (TIRF) is correct?
a) With TIRF, a resolution in the range of a few nm can be achieved independently of the NA of the imaging objective.
b) In TIRF, the fluorescence light is guided through fibers via total internal reflection to the photodetectors.
c) Due to the total reflection of the excitation laser light, the fluorescence is excited by an evanescent field within a layer of only 200 nm thickness, so that the axial resolution in TIRF can be very high.
d) TIRF is a scanning microscopy method, since the fluorescence is generated only in the focus due to the nonlinearity of total reflection.
e)TIRF only works with ultrashort laser pulses, since total internal reflection requires very high irradiances.
c) Due to the total reflection of the excitation laser light, the fluorescence is excited by an evanescent field within a layer of only 200 nm thickness, so that the axial resolution in TIRF can be very high.
What does the STED stand for in the super-resolution microscopy developed by Stefan Hell?
a) STED = Standard Excitation Development
b) STED = Stimulated Emission Depletion
c) STED = Standard Emission Darkness
d) STED = Super Transversal Excitation Directive
e) STED = Saturated Transmitted Emission Depletion
b) STED = Stimulated Emission Depletion
What is the advantage of fluorescence lifetime imaging microscopy (FLIM)?
a) It enables genetic encoding of fluorescence proteins.
b) It allows a high-speed recording at the picosecond scale, as it is based on nonlinear two-photon microscopy.
c) By employing a microscope objective with a higher numerical aperture (NA) it is possible to resolve single molecules.
d) It enables observation of the local environment of the fluorescence molecules.
d) It enables observation of the local environment of the fluorescence molecules.
What is an important advantage of two-photon microscopy over confocal microscopy for in vivo imaging?
a) The longer wavelength achieves a deeper penetration depth.
b) The introduction of nonlinear fluorescent molecules increases the survival rate of cells.
c) The generation of photon pairs makes molecular transporters visible.
d) The illumination is achieved through laser light, which prevents photobleaching of the dyes.
a) The longer wavelength achieves a deeper penetration depth.
What is time-correlated single-photon counting (TCSPC)?
a) TCSPC is a very fast method for spectral fluorescence imaging.
b) It accumulates single-photon arrival times in a histogram to determine the fluorescence decay time.
c) It correlates single molecules in the focus to measure diffusion times.
d) TCSPC is a single photon technology with high temporal resolution for accurate measurements of molecular concentrations.
b) It accumulates single-photon arrival times in a histogram to determine the fluorescence decay time.
How does Raman spectroscopy enable us to make statements about the structure of molecules?
a) Because Raman spectroscopy directly measures electronic transitions.
b) Because each molecule has as many clear Raman bands as it has atoms.
c) Because certain subgroups of molecules often have well separable and characteristic Raman bands.
d) Because chemical bonds have exactly one Raman band at a certain frequency.
e)Because an atomic species always vibrates at exactly one specific frequency.
c) Because certain subgroups of molecules often have well separable and characteristic Raman bands.
What is the main problem with Raman spectroscopy?
a) The high absorption of water in biological samples typically attenuates the light from the laser of the Raman measurement system.
b) The high scattering in tissue reduces the Raman signal.
c) The Raman scattering cross section is typically very small.
d) Raman systems use mid-infrared light, for which there are hardly any good optics available.
c) The Raman scattering cross section is typically very small.
What role do visualization methods play in modern microscopy?
a) Increase of the physical resolution
b) Protection of samples from photodamage
c) Acceleration of imaging
d) Visualization of complex 3-dimensional relationships in the sample
d) Visualization of complex 3-dimensional relationships in the sample
By which process can intracellular nanosurgery be realized with laser light in cells that are actually transparent?
a) The very high linear absorption of the irradiated laser light leads to very efficient energy deposition.
b) The irradiated photons are absorbed in the cell, so that due to the conservation of momentum a recoil is formed, which leads to a disruption of the cell structure.
c) Strong focusing of a laser pulse results in optical breakdown at the focus, where an expanding cavitation bubble disrupts the surrounding structures.
d) Homogeneous irradiation of the cells with a continuous laser leads to a photochemical process in which the cell membrane ruptures abruptly without a temperature increase.
c) Strong focusing of a laser pulse results in optical breakdown at the focus, where an expanding cavitation bubble disrupts the surrounding structures.
