Laboratory Report 3 Phase-Contrast A. Short-Answer Questions Staining of cells i

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Laboratory Report 3 Phase-Contrast A. Short-Answer Questions Staining of cells is ofiten performed so enhance imapes acquired by bicocoy Phase contrast microcopy s roqung cell st why is thi·abatapum? phase shift occurs? How do coincidence and interference of lgh eays diffes? What type o image does eah peodace Ho docs thait contnibulc to a sharper imape 4· Differentiate between brighephase and dark-phase masopy in mof phae Which two items can be used to check the alignment of the annulus and phse ring ANSWERS B Multiple Choice by huving a ocular lens h diaphragm wih an annolar stop c phase plate in the objective les All ate cOTE 23 2. Which of the following would be best obsoved for a hacterial cell 2. using phase-comrast microsopy? a. Mbtility of cells h. Bacterial looid d. Glycocalyx Ampliaude summation occurs in phase-costrast optics when bodh direct and diffracted tays are a. in phasc h in revense phase d. None of these are ceerect

Explanation / Answer

in many cases, cell staining would lead to cell cell death. As a result of which, the movement of cells cannot be tracked if stained. Hence, phase contrast is advantageous. For the direct rays, there would be no phase shift as the rays will be unaffected. For the diffracted rays, there would be a Bend, as a result, there would be a phase shift by 1/4 of wavelength. Coincidence rays result in formation of brighter images whereas, interference rays result in formation of darker images. In bright phase microscopy, there is an amplitude summation, that results in brighter images. Whwereas, in dark phase microscopy, there is interference of amplitudes, resulting in darker images. The two items that could be used for checking of alignments of the phase ring as well as the annulus are the optovar as well as the ce-ntering telescope. D) Both b and c: as there is a difference in the diaphragm as well as the annular stop along with the objective lens having the phase plate. A) Motility of cells, A) in phase

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