MLT GlobeDHA exam preparation (Dubai) – page 10
700 practice MCQs for the DHA medical laboratory exam. Level: Basic to intermediate.
Which of the following is NOT a haemoflagellate?
Plasmodium knowlesi is an apicomplexan malaria parasite with no flagellum. The trypanosomes are flagellated blood parasites.
Which of these parasites is NOT transmitted by mosquitoes?
Leishmania is transmitted by sandflies. Plasmodium is spread by Anopheles, and W. bancrofti by Culex, Anopheles or Aedes mosquitoes.
Which medium is the standard primary culture medium for isolating fungi from clinical specimens?
SDA has a low pH and high glucose that favour fungi, often with antibiotics added to suppress bacteria.
In a wet mount of vaginal discharge, the jerky, twitching movement of Trichomonas vaginalis is produced by:
T. vaginalis has four anterior flagella and a short undulating membrane with a recurrent flagellum. Cilia belong to Balantidium and pseudopodia to amoebae.
A patient has itchy burrows between the fingers. Which laboratory procedure best confirms scabies?
Sarcoptes scabiei lives in epidermal burrows, so scraping the burrow and examining it in oil or KOH shows mites, eggs or scybala. Blood and stool tests are not useful.
Which parasitic infection is usually afebrile?
The dwarf tapeworm H. nana usually causes mild or no gut symptoms without fever. Naegleria meningoencephalitis, malaria and the invasive phase of trichinellosis all cause fever.
Why can P. vivax and P. ovale cause attacks months after the first episode has cleared?
Hypnozoites are dormant liver forms that later resume development, causing true relapse. Primaquine or tafenoquine is needed to clear them.
To detect Wuchereria bancrofti microfilariae in most endemic regions, blood should be collected:
Most W. bancrofti strains show nocturnal periodicity, peaking in blood at night when Culex vectors bite. Loa loa has diurnal periodicity.
Which name does not belong to a human Schistosoma species?
Buski refers to Fasciolopsis buski, the giant intestinal fluke. S. haematobium, S. mansoni and S. japonicum are the main human blood flukes.
What is the usual diagnostic stage of Ascaris lumbricoides in stool?
Eggs with a thick mammillated coat are shed in large numbers and identified on wet mount. Cysts and trophozoites are protozoan stages.
After an infected Anopheles bite, where do Plasmodium sporozoites first go to multiply in the human body?
Sporozoites travel to the liver and undergo exo-erythrocytic schizogony in hepatocytes. Only the merozoites released from the liver invade red cells.
A key effector role of complement is to:
Complement bound to antibody-coated cells can form the membrane attack complex and lyse them. Phagocytosis is performed by cells, not complement.
What is the main function of MHC class I and class II molecules?
MHC class I presents peptides to CD8 T cells and class II to CD4 T cells. Intracellular signalling is performed by CD3.
Which statement about interleukins is FALSE?
Interleukins are signalling proteins that act through receptors; they do not recognize antigens.
What is the main role of lymphokines?
Lymphokines are cytokines secreted by lymphocytes that activate and coordinate other immune cells.
Hypersensitivity types I, II and III share which feature?
Types I (IgE), II (IgG/IgM on cells) and III (immune complexes) involve antibodies, whereas type IV is T-cell mediated.
Which hypersensitivity type is mediated by T cells rather than antibody?
Type IV (delayed) reactions are driven by sensitized T cells and macrophages, as in tuberculin testing and contact dermatitis.
Which of these is NOT an autoimmune disease?
SCID is a primary immunodeficiency. Graves, RA and Addison disease involve autoimmunity.
Severe combined immunodeficiency is characterized by defective:
SCID affects both T cells and B-cell (antibody) responses. Selective IgA deficiency is a milder humoral defect.
Which is NOT an immunodeficiency disorder?
Graves disease is autoimmune (TSH-receptor antibodies). SCID, DiGeorge and hyper-IgM syndrome are immunodeficiencies.