Question

68. The Acid-fast stain                                                                                                                                         

A. is a differential stain that is helpful in diagnosing Mycobacterium tuberculosis.                                       

B. uses heat as a mordant.                                                                                                                                                   

C. Acid- fast organisms appear blue in color.                                                                                                                                   

D. is used to stain bacteria that have waxy mycolic acid layer.                                                                       

E. All of the above                                                                                                                                                           

F. A and D                                                                                                                                                                                   

G. All except C                                                                               

69. If an antimicrobial chemical has a PHENOL COEFFICIENT of 25, then which of thefollowing statements is TRUE?                                                                                                                                                                      

A. It will kill 25 times more bacteria than phenol.                                                                                              

B. It is 25-times less effective than phenol.                                                                                                         

C. It must be concentrated 25-times to have the same effect as phenol.                                                                      

D. It can be diluted twenty-five times and still have the same killing effect as phenol.                                     

E. It will kill bacteria 25-times faster than phenol.

70. The greatest resolution in light microscopy can be obtained with ___________
A. Longest wavelength of visible light used
B. An objective with minimum numerical aperture
C. Shortest wavelength of visible light used
D. Shortest wavelength of visible light used and an objective with the maximum numerical aperture

Answer 1

68. G

70. D

Explanation

68. Acid fast stain is the differential staining method to stain the bacteria which are not stained by gram satin. Used mainly in mycobacterium with wax like impermeable cell wall made of mycolic acid.Acid fast bacterial cell appear red in colour while non acid fast group are seen as blue colour, after the satining procedure .

70. resolution indicates the ability to distinguish two closely spaced objects as seperate entities. it indicate sharpness of the image. Shorter wave lenght yield higher resolution. Greater resolution near UV region.Higher the numerical aperture of the system better will be the resolution. A lense with larger numerical apperture can resolve the image better.