Laboratory Techniques and Procedures Questions and Answers Flashcards
6 cards from real MLPAO practice questions. Tap to flip, then mark Knew It or Still Learning — missed cards come back until you master them.
Read the first 6 Laboratory Techniques and Procedures Questions and Answers flashcards as text
What is the principle of the quantitative immunoglobulin measurement by nephelometry?
Answer: Measurement of light scattered by antigen-antibody complexes to determine protein concentration
Nephelometry measures the intensity of laser light scattered at an angle by antigen-antibody complexes formed when patient immunoglobulins bind to specific antibody reagents. Scatter intensity is proportional to protein concentration.
During a peripheral blood film examination, a medical laboratory technologist observes red blood cells with a single pale area and a dense hemoglobin border around the edge. What is the name of these cells?
Answer: Target cells (codocytes)
Target cells (codocytes) are RBCs with a bull's-eye appearance — a central dense area and peripheral ring of hemoglobin separated by a pale zone — caused by excess membrane relative to hemoglobin content.
What is the clinical significance of a positive DAT (direct antiglobulin test/direct Coombs) result?
Answer: Immunoglobulin or complement is bound to the patient's red blood cells in vivo
A positive DAT indicates that IgG antibody or complement (C3d) is coating the patient's own RBCs in vivo, indicating immune-mediated RBC sensitization.
Which culture medium is selective and differential for the isolation of Salmonella and Shigella from stool specimens?
Answer: Salmonella-Shigella (SS) agar or Hektoen enteric agar
SS agar and Hektoen enteric agar are selective (inhibiting normal flora with bile salts and dyes) and differential (detecting lactose fermentation and H2S production) media designed to isolate enteric pathogens.
In clinical chemistry, what is the difference between an 'endpoint' and a 'kinetic' (rate) assay?
Answer: Endpoint assays measure absorbance after the reaction is complete; kinetic assays measure the rate of absorbance change during the reaction
Endpoint assays measure absorbance after the reaction has gone to completion; kinetic assays measure the rate of absorbance change per minute during the reaction, which is proportional to enzyme activity or analyte concentration.
What does the term 'cross-reactivity' mean in the context of immunoassay design?
Answer: An antibody's unintended reaction with a structurally similar but different molecule than its intended target
Cross-reactivity occurs when an antibody recognizes and binds to a molecule structurally similar to but different from its intended target antigen, potentially causing false-positive or falsely elevated results.