MLPAO Laboratory Techniques and Procedures Questions and Answers 2

Question 1

What technique is used to separate DNA fragments by size during gel electrophoresis?

Accepted Answer

Migration through an agarose gel matrix under an electrical current

Answer

Centrifugation based on molecular density

Answer

Precipitation by salt concentration

Answer

Filtration through a molecular sieve membrane

Question 2

What is the principle of the polymerase chain reaction (PCR) in molecular diagnostics?

Accepted Answer

Amplification of specific DNA sequences through repeated cycles of denaturation, annealing, and extension

Answer

Separation of DNA fragments by size in a gel matrix

Answer

Detection of protein antigens using antibody-enzyme conjugates

Answer

Translation of mRNA sequences into protein

Question 3

In clinical microbiology, what is the purpose of inoculating a blood agar plate and a chocolate agar plate simultaneously when processing a respiratory specimen?

Accepted Answer

Blood agar detects beta-hemolytic organisms; chocolate agar supports fastidious organisms like Haemophilus and Neisseria that require growth factors released by heated RBCs

Answer

Blood agar supports fastidious organisms; chocolate agar supports anaerobes only

Answer

Both media are equivalent — inoculating both ensures redundancy

Answer

Chocolate agar inhibits normal flora while blood agar supports all organisms

Question 4

Which laboratory method is used as the reference (gold standard) for diagnosing malaria?

Accepted Answer

Microscopic examination of Giemsa-stained thick and thin blood films

Answer

Malaria rapid antigen test (RDT)

Answer

PCR for Plasmodium species

Answer

ELISA for Plasmodium antibodies

Question 5

What type of pipette is most appropriate for delivering a precise volume of 100 μL for an ELISA assay?

Accepted Answer

Calibrated micropipette (100 μL fixed or adjustable)

Answer

Serological pipette (1 mL)

Answer

Pasteur pipette

Answer

Graduated glass pipette (1 mL TD)

Question 6

What is the CMLTO-recognized clinical significance of performing an extended red blood cell antigen typing before first transfusion in a patient with sickle cell disease?

Accepted Answer

To establish a baseline antigen profile to guide compatible RBC unit selection and prevent alloimmunization

Answer

To determine ABO compatibility only

Answer

To identify which blood group system is most immunogenic

Answer

To detect pre-formed antibodies from previous transfusions