096/23

51. Which fluorescent dye is used to stain bacterial nucleic acids in fluorescence
microscopy ?
A) Cyanoditolyl Tetrazolium Chloride (CTC) B) Auramine
C) Rhodamine D) Acridine Orange

52. In the table given below, Column | shows different microscopy techniques and

Column II shows major uses of the different microscopy techniques. Select the correct
combination.

Column! Column Il

Observation of dead stained organisms or live ones

1 | Bright Field | with sufficient natural colour contrast

Observation of unstained living or difficult-to-
stain organisms; allows one to see motion

2 | Dark Field |

Diagnostic tool for detection of organisms
3 | Fluorescence or antibodies in clinical specimens or for
immunologic studies

|4 | Confocal Observation of very specific levels of specimen

Observation of exterior surfaces of atoms or
Transmission Electron
molecules

Examination of thin sections of cells for details of
Scanning Tunneling internal structure, exterior of cells, and viruses,
or surfaces when freeze-fracturing is used

A) 1-a,2-b,3-f,4-e,5-d,6-c B) 1-a,2-b,3-c,4-d,5-f,6-e

C) 1-a,2-b,3-e,4-d,5-c,6-f D) 1-a,2-b,3-f, 4-d,5-c,6-e
53. Which step of the Gram staining process is responsible for the differentiation of

Gram-positive and Gram-negative bacteria ?

A) Application of crystal violet ©) Decolorization with ethanol or acetone

C) Application of iodine D) Counterstaining with safranin

54. Which of the following statements about lyophilization are true ?

A) Rapidly frozen organisms in vials are subjected to a vacuum instrument that
removes water from them and seals the vials under vacuum

B) The process allows large ice crystals to form inside the cell ensuring their
preservation

C) Microbiologists use lyophilization for destruction of cultures of microorganisms
rather than for long-term preservation

D) All of the above