MLT GlobeMOH exam preparation (UAE) – page 19
700 practice MCQs for the MOH medical laboratory exam. Level: Basic to intermediate.
Cardiolipin, the antigen used in non-treponemal syphilis tests such as VDRL, is concentrated in the:
Cardiolipin (diphosphatidylglycerol) is characteristic of the inner mitochondrial membrane, which is also low in cholesterol. The plasma membrane and myelin are cholesterol-rich.
Making one glucose from two lactate molecules in the liver consumes how many high-energy phosphate bonds?
Pyruvate carboxylase uses 2 ATP, PEP carboxykinase 2 GTP, and phosphoglycerate kinase 2 ATP, totalling 6. The Cori cycle therefore costs the liver more than the 2 ATP muscle gains.
Which one-carbon unit is NOT carried by tetrahydrofolate?
Tetrahydrofolate carries formyl, methenyl, methylene and methyl groups. CO2 is carried by biotin in carboxylation reactions.
Which electron-carrying protein uses haem, not FAD or FMN, as its prosthetic group?
Cytochrome c is a haem protein that shuttles electrons between Complexes III and IV. Complex I (FMN), succinate dehydrogenase (FAD) and xanthine oxidase (FAD) are flavoproteins.
Deficiency of which lipotropic nutrient causes fatty liver by impairing phosphatidylcholine synthesis and VLDL export?
Phosphatidylcholine is needed to assemble and secrete VLDL. Without choline, triglyceride builds up in hepatocytes.
Which fat-soluble vitamin acts as a membrane antioxidant alongside the selenium-containing enzyme glutathione peroxidase?
Vitamin E breaks lipid-peroxidation chains in membranes. Selenium-dependent glutathione peroxidase removes peroxides, so the two nutrients spare each other.
Which molecule acts as a coenzyme, carrying acyl groups in the pyruvate dehydrogenase complex?
Lipoic acid, bound to E2 as lipoamide, carries the acetyl group and electrons between subunits. Glucose-6-phosphate and glucose-1-phosphate are metabolic intermediates, not coenzymes.
Most of the body's vitamin A is stored as retinyl esters in which cells?
Hepatic stellate cells store about 80% of body vitamin A as retinyl esters. When these cells are activated in liver injury, they lose this store and lay down fibrous tissue.
Once Köhler illumination has been set, which action should NOT be used to reduce image brightness?
Condenser height and aperture are set for resolution and contrast during Köhler alignment; altering them degrades the image. Brightness should be changed with the rheostat or neutral density filters.
Platelet concentrates kept at 20–24 °C with agitation have what standard shelf life, unless an approved bacterial risk-control method is used?
Room-temperature storage risks bacterial growth, so the routine limit is 5 days; extension to 7 days is permitted only with approved bacterial detection or pathogen reduction. 35 days applies to red cells.
A young adult with liver disease and neuropsychiatric symptoms is suspected of Wilson disease. Which serum finding supports this?
Wilson disease (ATP7B defect) impairs copper incorporation into ceruloplasmin and biliary excretion, so ceruloplasmin is low while urinary copper rises.
Which gastric finding is expected in pernicious anemia?
Autoimmune destruction of parietal cells abolishes acid and intrinsic factor secretion. Achlorhydria drives G-cell hyperplasia, so gastrin is high; anti-intrinsic factor antibodies occur in about half of patients.
In a tube crossmatch, the phase that detects IgG antibodies coating donor red cells requires:
IgG antibodies sensitize cells without agglutinating them in saline; after 37 °C incubation, AHG bridges the coated cells. The immediate-spin saline phase detects ABO incompatibility.
In polycythemia vera, serum erythropoietin is typically:
The JAK2-mutant clone proliferates independently of erythropoietin, and feedback suppresses EPO. A high EPO points to secondary erythrocytosis such as hypoxia or renal tumors.
In current practice, cryoprecipitate is transfused mainly to replace:
Cryoprecipitate is rich in fibrinogen, factor VIII, vWF and XIII. Hemophilia A and vWD now use factor concentrates, so its main use is hypofibrinogenemia, e.g. in massive bleeding.
After an RhD-negative mother delivers an RhD-positive baby, which test estimates fetomaternal hemorrhage to calculate the anti-D dose?
Fetal cells containing HbF resist acid elution and stain pink, allowing counting of fetal cells in maternal blood; flow cytometry is an alternative. The Singer test measures HbF, not cells.
Which of these laboratory tests is based on an agglutination reaction?
In the RF latex test, IgG-coated latex particles clump visibly when RF binds them. Immunodiffusion and immunofixation are precipitation methods; ELISA uses enzyme labels.
In which neonatal situation is fresh frozen plasma appropriately indicated?
FFP replaces multiple coagulation factors, so it suits bleeding neonates with DIC (or vitamin K deficiency bleeding, factor deficiencies). It carries no red cells and should not be used for volume alone.
HLA antibodies, typically formed after pregnancy or transfusion, are chiefly of which class?
Alloimmunisation to HLA produces mainly IgG antibodies, which cause platelet refractoriness, febrile reactions and transplant rejection.
Which patient is NOT an appropriate candidate for fresh frozen plasma?
FFP replaces clotting factors and ADAMTS13. Sensitisation to leukocyte or platelet antigens calls for leukoreduced or HLA-matched products, not plasma.