MLT GlobeMOH exam preparation (UAE) – page 23
700 practice MCQs for the MOH medical laboratory exam. Level: Basic to intermediate.
A soft contact lens wearer who rinses lenses in tap water develops a painful ring-shaped corneal infiltrate. Which organism is most likely?
Acanthamoeba causes sight-threatening keratitis in contact lens users; corneal scrapings show double-walled cysts. Naegleria causes acute meningoencephalitis, not keratitis.
Which statement correctly describes trematodes (flukes)?
Flukes are acoelomate flatworms with leaf-shaped unsegmented bodies. Cylindrical bodies with a pseudocoelom describe nematodes, and segmented ribbons describe cestodes.
Beef containing which larval stage transmits Taenia saginata to humans?
Cysticercus bovis in cattle muscle develops into the adult worm. C. cellulosae is the T. solium larva, the coracidium belongs to Diphyllobothrium, and the miracidium to flukes.
Chronic infection with which Plasmodium species is most associated with nephrotic syndrome, especially in children?
Quartan malarial nephropathy is caused by immune-complex glomerulonephritis in P. malariae infection. P. falciparum more often causes acute kidney injury, not nephrotic syndrome.
In bacterial conjugation or transduction, a recipient cell that is diploid for only part of its genome is called a:
Transfer of a DNA fragment makes the recipient a partial diploid, or merozygote; the process is called meromixis. Heterokaryons and zygospores are fungal terms.
Cytoadherence of P. falciparum-infected red cells to the endothelium of brain vessels leads mainly to:
Knobs with PfEMP1 make infected cells stick to cerebral endothelium, blocking microcirculation and causing coma. Blackwater fever is due to massive hemolysis.
The nephrotic syndrome of Plasmodium malariae infection is caused by:
Antigen-antibody complexes deposit in the glomeruli, causing membranoproliferative injury and proteinuria. Hypoproteinemia is a result, not a cause.
Which malaria parasite mainly infects older (senescent) red cells?
P. malariae prefers aged red cells, which keeps parasitemia low. P. vivax and P. ovale prefer reticulocytes, while P. falciparum invades red cells of all ages.
Which finding is not a typical feature of severe falciparum malaria?
WHO criteria for severe malaria include impaired consciousness, seizures, hypoglycemia and shock. Generalized lymph node enlargement is not a feature.
A patient from South Asia has nocturnal cough, wheeze, very high eosinophils and high anti-filarial antibodies. This tropical pulmonary eosinophilia is linked to:
Tropical pulmonary eosinophilia is an immune reaction to microfilariae of W. bancrofti or Brugia trapped in the lungs. It responds to diethylcarbamazine.
Which helminth produces operculated eggs?
D. latum eggs have an operculum (lid) at one end, as do Fasciola, Paragonimus and Clonorchis. Schistosome eggs have spines but no operculum.
Which protozoan has no flagella, cilia or pseudopodia and moves by gliding?
Apicomplexans such as Toxoplasma lack locomotory organelles and use gliding motility. Amoebae use pseudopodia, while Giardia and Trichomonas have flagella.
Crescent-shaped tachyzoites that multiply inside nucleated host cells by endodyogeny are characteristic of:
Toxoplasma tachyzoites are arc-shaped and divide by internal budding within many cell types. P. falciparum gametocytes are crescent-shaped but do not multiply, and Plasmodium reproduces by schizogony.
Streptococcus suis, a cause of meningitis and deafness in humans, is acquired mainly from:
S. suis is a swine pathogen; pig farmers and people who handle or eat raw pork are at risk. Person-to-person spread is not recognised.
A T cell ignores a soluble protein that a B cell recognizes. The best explanation is that the T-cell receptor:
TCRs are MHC-restricted, recognizing processed peptides presented by MHC. Antibodies and BCRs bind free, native antigen directly.
What do the T-cell receptor and antibody have in common?
Both BCR and TCR are membrane receptors. Only antibodies are secreted, switch class or contain J chains.
Laboratory diagnosis of most systemic and organ-specific autoimmune diseases relies mainly on detecting:
Autoantibodies (e.g., anti-dsDNA, anti-TPO, AChR antibodies) are measurable serum markers of lost self-tolerance, even in diseases where tissue damage is largely T-cell mediated, such as type 1 diabetes and rheumatoid arthritis.
A mature naive B cell has on its surface:
Naive B cells express monomeric IgM (with IgD) of a single specificity as the B-cell receptor.
Allergen immunotherapy (desensitisation) is thought to work partly by inducing an antibody that intercepts allergen before it reaches mast-cell IgE. Which class is this?
Repeated allergen doses shift the response toward allergen-specific IgG, mainly IgG4, which binds allergen and prevents IgE cross-linking on mast cells.
Which innate immune cell is most critical for clearing invasive Candida and Aspergillus infections, as shown by risk in neutropenic patients?
Neutropenia is the major risk factor for invasive candidiasis and aspergillosis because neutrophils kill hyphae and yeasts by oxidative burst. Antibody (B cells) plays a minor role.