MLT GlobeDHA exam preparation (Dubai) – page 18
700 practice MCQs for the DHA medical laboratory exam. Level: Basic to intermediate.
Japanese encephalitis virus is transmitted to humans mainly by:
Culex mosquitoes breeding in rice fields transmit JE virus between pigs, water birds and humans.
The international biohazard symbol on waste bags and containers is usually printed in which colour?
Biohazard labels are fluorescent orange or orange-red with the symbol in a contrasting colour, often on red bags.
How should liquids be pipetted in a clinical laboratory?
Mouth pipetting is prohibited because of the risk of swallowing infectious or toxic material.
Before disposal, infectious microbiology waste such as used culture plates is commonly decontaminated by:
Steam sterilisation in an autoclave kills micro-organisms, including spores, before waste leaves the laboratory.
In the RACE fire response plan, what does the letter R stand for?
RACE means Rescue, Alarm, Contain (confine) and Extinguish or Evacuate.
Precision of a laboratory method refers to:
Precision is reproducibility; closeness to the true value is accuracy.
The gel in a serum separator tube (SST) serves to:
The gel has a density between serum and cells, so it moves up to form a barrier during centrifugation.
For a fingerstick in an adult, the recommended site is the:
The middle and ring fingers have enough tissue; the thumb has a pulse and the little finger has too little tissue over bone.
To make a 1:10 dilution using 0.2 mL of serum, what should the total final volume be?
In a 1:10 dilution the sample is one tenth of the total volume, so 0.2 mL × 10 = 2.0 mL total (0.2 mL serum + 1.8 mL diluent).
Most laboratory reagents and kits that need refrigeration are stored at:
Refrigerated storage is 2–8 °C; temperatures should be recorded daily.
Before a helper T cell can help a B cell make antibody, the helper T cell itself must first be activated by:
T cells recognise only processed peptide presented on MHC. Dendritic cells and macrophages present antigen on MHC II to CD4 cells, which then activate B cells.
On an indirect immunofluorescence ANA test using HEp-2 cells, the entire interphase nucleus stains evenly. This homogeneous pattern is most associated with antibodies to:
A homogeneous (diffuse) nuclear pattern reflects anti-dsDNA/anti-histone/nucleosome antibodies, seen in SLE and drug-induced lupus. Centromere gives discrete speckles; mitochondria stain cytoplasm.
Which of these is NOT part of innate (non-specific) immunity?
Antibodies in breast milk are specific and represent naturally acquired passive immunity. Lysozyme, commensal flora and gastric acid are innate barriers.
Which feature is NOT typical of mycetoma (Madura foot)?
Mycetoma is a chronic painless swelling with sinuses discharging grains, caused by fungi or actinomycetes. Systemic fever is not typical.
Which organism does NOT typically cause vaginal discharge?
Cryptococcus causes meningitis and lung disease. The others are associated with vaginosis, vaginitis or cervicitis with discharge.
When should a blood film be collected from a patient with suspected malaria, according to current guidance?
WHO/CDC advise sampling as soon as malaria is suspected, before treatment and regardless of fever timing; if negative, films are repeated (usually every 12–24 h, three sets). Waiting for a paroxysm delays diagnosis.
Which protozoal infection is typically self-limiting in immunocompetent people but may become chronic and life-threatening in AIDS?
Cryptosporidium diarrhoea resolves within about two weeks in healthy hosts but can be severe and persistent with low CD4 counts. Untreated kala-azar, PAM and severe falciparum malaria are often fatal regardless.
Horse flies (Tabanus) are known to transmit which infection mechanically via contaminated mouthparts?
Tabanids can mechanically transmit Bacillus anthracis and Francisella tularensis. Leishmaniasis is spread by sandflies, malaria by Anopheles, and typhoid faeco-orally.
Which intestinal protozoan exists only as a trophozoite and does not form cysts?
Pentatrichomonas (Trichomonas) hominis, like other trichomonads, has no cyst stage. Balantidium, Giardia and E. histolytica are transmitted as cysts.
For which parasite are pigs or dogs NOT a usual source of human infection?
A. lumbricoides spreads human to human via soil-contaminated eggs. Pigs transmit T. solium and Trichinella, and dogs shed Echinococcus eggs.