Microscopy, Centrifugation, Spectrophotometry and Photometry

Which is the best method for examination of synovial crystals?

Polarized lighT

All of the following statements about fluorometry are true, EXCEPT:

Fluorescence is indirectly proportional to the analyte being measured.

Which of the following analytes would be decreased due to delay in centrifugation?

Folate

Which of the following analytes would be decreased due to delay in centrifugation?

Glucose

When operating a centrifuge, what happens if the centrifugation time is reduced and the speed increased?

Hemolysis of red cells can occur.

A spectrophotometric scan of amniotic fluid may be valuable in the determination of which of the following conditions:

Hemolytic disease of the newborn

Periodic verification that a centrifuge is operating correctly is determined by:

Measuring RPM with a tachometer

Which of the following analytes would be increased due to delay in centrifugation?

Potassium

Which of the following BEST describes the relation of nephelometry to turbidimetry?

Nephelometry directly measures the amount of light scattered by particles in solution, and turbidimetry measures the decrease in incident-light intensity

Identify the objectives and condenser in the image on the right.

G, I

Identify the Light intensity control and Stage controls.

H, F

Spectrophotometric absorbance is related to % transmittance in what way:

Inversely and logarithmically

Which of the following analytes would be decreased due to delay in centrifugation?

Ionized Calcium

Which of the following does the most to minimize aerosol production during centrifugation?

Using stoppered centrifuge tubes or a cover over the rotor chamber

What is the minimum amount of time a specimen without additive or anticoagulant should be allowed to clot before centrifugation?

30 minutes

At a minimum, how frequently should an ocular micrometer be calibrated?

After major cleaning of the microscope or replacing objectives

How many microns are equivalent to one ocular micrometer at 40X given the following information? Stage micrometer: 0.4 Ocular micrometer: 53

7.5

In absorbance spectrophotometry

Absorbance is directly proportional to concentration

Identify the eye piece and diopter adjustment:

B, E

How many microns are equivalent to one ocular micrometer unit at 100X given the following information? ocular micrometer units: 50 stage micrometer units: .05

1.0 µm

The volume of urine recommended for centrifugation for a microscopic examination is:

10 - 15 mL

The wavelength of the light measured by a spectrophotometer is generally designated in nanometers. A nanometer is equal in meters to:

10-9 meters

With most light microscopes, what is the total magnification if using the objective lens that is closest to the specimen along with the ocular lens?

1000X

In the steps involved in performing a bone marrow differential what objective is used and how many cells must be counted?

100x (oil), 200 cells

Absorbance (A) of a solution may be derived from percent transmittance using which formula?

2- log%T

Of the following centrifuges, which one is properly loaded and balanced?

3

Identify the body/frame and illuminator/diaphragm in the image to the right.

A & J

Which of the following analytes would be increased due to delay in centrifugation?

ALT

Which of the following analytes would be increased due to delay in centrifugation?

AST

Beer's law states that concentration is directly proportional to which of the following?

Absorbance

All of the following are components of a basic single beam spectrophotometer, except:

Beam splitter

All of the following statements are true regarding the significance of performing direct microscopic examinations of specimens for culture, EXCEPT:

Allows the microbiologist to discard the sample and cancel testing if no organisms are observed.

If a plasma glucose specimen is not centrifuged, how will the test results be affected?

The glucose test result may be decreased.

When operating a centrifuge, what happens if the centrifuge is not properly balanced?

The potential breakage of collection tube is highly increased.

A chemical reaction that is utilized by many different analytical methods involves:

The reduction of NAD to NADH

When operating a centrifuge, what happens if the centrifugation time is reduced and the speed increased?

There will be incomplete separation of red blood cells and serum in the tube.

All of the following affect the relative centrifugal force of a centrifuge, EXCEPT?

Time

A tube has broken during centrifuging, what is the most likely reason?

Tube was not properly balanced in the centrifuge

What is the maximum recommended amount of time a specimen without additive or anticoagulant should be allowed to clot before centrifugation?

Two hours

Which of the following instruments measures light scatter by particles?

Nephelometer

What is the total magnification produced when using a 10X ocular lens and a 40X objective lens on a Bright Field light microscope?

400x

Which of the following analytes would be decreased due to delay in centrifugation?

Bicarbonate

Which of the following organisms is best visualized by use of a darkfield microscope?

Borrelia

Identify the Revolving nosepiece and Mechanical stage

C, D

Which part of the spectrophotometer is used for the isolation of individual wavelengths of light?

Diffraction grating

Which of the following instruments measures the amount of electricity passing between two electrodes?

Coulometer

Which of the following analytes would be increased due to delay in centrifugation?

Creatinine

Which of the following microscopic techniques is best suited for direct examination of the infectious agent of syphilis?

Dark-field microscopy

All of the following forms of microscopy are commonly used in the clinical laboratory, EXCEPT?

Electron microscopy

When operating a centrifuge, what happens if the centrifuge is not properly balanced?

Exposure to biohazardous agents

What part of the spectrophotometer isolates individual wavelengths of light?

Monochromator

The biuret reaction for the analysis of serum protein depends on the number of:

Peptide bonds

What is the BEST type of microscopy for performing manual platelet counts?

Phase contrast

When operating a centrifuge, what happens if the centrifuge is not properly balanced?

Potential breakage of collection tubes

Fluorometers are designed so that the path of the excitation light is at a right angle to the path of the emitted light. What is the purpose of this design?

Prevent incident light from striking the detector

When operating a centrifuge, what happens if the centrifugation time is reduced and the speed increased?

Residual separator gel particles may be present in the serum

Deviations from Beer's Law are caused by:

Stray light

Which of the following microscopic techniques is capable of producing a 3-dimensional image:

Scanning electron microscope

All of the following should be done when centrifuging specimens, EXCEPT?

Specimens with anticoagulant should sit for 20 minutes before centrifugation.

Which of the following instruments measures absorbance of light at a specific wavelength?

Spectrophotometer

Which of the following represents a diagram of a spectrophotometer

light source - monochromator - cuvette - detector - readout

Which of the following instruments measures changes in vapor pressure?

Osmometer

In automated methods utilizing a bi-chromatic analyzer, the dual wavelengths are employed to:

Minimize the effect of interference

All of the following are laboratory centrifuges, EXCEPT?

Ultraviolet (UV) centrifuge

What do the majority of centrifuge accidents stem from?

User error