MLT GlobeDOH exam preparation (Abu Dhabi) – page 18
700 practice MCQs for the DOH medical laboratory exam. Level: Basic to intermediate.
Thoracentesis is performed to collect which fluid?
Thoracentesis is needle aspiration of the pleural space. Paracentesis collects peritoneal fluid, pericardiocentesis pericardial fluid and arthrocentesis synovial fluid.
Amniotic fluid is collected by which procedure?
Amniocentesis is transabdominal needle aspiration of amniotic fluid from the amniotic sac, used for genetic and fetal testing.
Fungal hyphae with regular cross-walls are described as:
Septate hyphae have cross-walls (septa), as in Aspergillus and dermatophytes; Mucorales have mostly aseptate hyphae.
Cryptococcus neoformans is commonly found in the environment in:
C. neoformans grows well in soil enriched with pigeon droppings; infection follows inhalation.
Routine fungal cultures for moulds are usually incubated at:
Most moulds grow best at 25–30 °C; 37 °C is used additionally to show the yeast phase of dimorphic fungi.
Vaginal candidiasis typically produces a discharge that is:
Candida gives a cottage-cheese-like discharge with itching; frothy discharge suggests Trichomonas and fishy grey discharge suggests bacterial vaginosis.
Candida albicans is best described as:
C. albicans is normal flora of the mouth, gut and vagina and causes disease when defences or normal flora are disturbed.
After a chemical splash to the eyes, they should be flushed at the eyewash station for at least:
Continuous flushing for at least 15 minutes is recommended to remove the chemical, followed by medical review.
Most laboratory errors occur in which phase of testing?
Errors in ordering, patient identification, collection, labelling and transport account for most laboratory errors.
A written, step-by-step document describing exactly how a test is performed in the laboratory is called a:
SOPs ensure every staff member performs the test the same way and are part of document control.
A patient with macrocytic anaemia has normal folate. Which raised urinary metabolite best supports cobalamin deficiency?
Methylmalonyl-CoA mutase needs vitamin B12; without it methylmalonic acid accumulates and is excreted. Folate deficiency raises homocysteine but not methylmalonate.
Which amino acid most strongly favours formation of an α-helix?
Alanine's small, uncharged side chain fits the helix well. Proline's rigid ring breaks helices, and glycine is too flexible.
Enzymes that transfer the amide nitrogen of glutamine to acceptors (e.g., in purine synthesis) belong to which class?
Amidotransferases hydrolyse glutamine's amide and pass the NH3 to substrates such as PRPP. Glutamine synthetase forms glutamine rather than using it.
Which statement about protein secondary structure is correct?
Proline's fixed angle and glycine's flexibility suit tight β-turns. β-Sheets can be parallel or antiparallel, and α-helices are stabilised by backbone hydrogen bonds within one chain.
Which lipid is a glycerol-based ether phospholipid lacking sphingosine?
Plasmalogens have a vinyl-ether link at glycerol C1. Sphingomyelin, cerebrosides and gangliosides are built on sphingosine.
Mixing which pair of solutions produces a buffer?
Partial neutralisation leaves weak base NH4OH together with its salt NH4Cl, a buffer pair. Strong acid–strong base mixtures and excess strong base cannot buffer.
Which drug lowers leukotriene production without inhibiting cyclooxygenase?
Zileuton blocks 5-lipoxygenase, the leukotriene pathway, and is used in asthma. Ibuprofen, indomethacin and aspirin are COX inhibitors.
The pyruvate dehydrogenase complex requires TPP, lipoate, FAD, NAD⁺ and which other cofactor?
Coenzyme A accepts the acetyl group, producing acetyl-CoA. Pyridoxal phosphate serves transaminases; biotin serves carboxylases.
If sucrose is injected intravenously, what happens to it?
Sucrase exists only on the intestinal brush border, so circulating sucrose is not hydrolysed and is filtered by the kidneys unchanged.
Which structural feature is shared by glycosaminoglycans such as hyaluronate and chondroitin sulfate?
GAGs are long linear polymers of repeating disaccharides (amino sugar plus uronic acid). Carboxyl and sulfate groups make them strongly negative, not positive.