MLT GlobeMOH exam preparation (UAE)
700 practice MCQs for the MOH medical laboratory exam. Level: Basic to intermediate.
Subject mix: Chemistry 17%, Hematology 16%, Bacteriology 14%, Blood Banking 12%, Immunology & Serology 10%, Urinalysis & Body Fluids 7%, Parasitology 7%, Laboratory Operations 7%, Virology 5%, Mycology 5%
Intact skin, mucus, cilia and gastric acid make up which line of defence?
Surface barriers are the first line of defence. Phagocytes and inflammation are the second line, and lymphocytes and antibodies are the third (adaptive) line.
What is the main role of epidermal Langerhans (dendritic) cells?
Langerhans cells are skin dendritic cells that take up antigens and carry them to lymph nodes for presentation. Arrector pili muscles raise hairs, and melanocytes make pigment.
Hair and nails are tough because their main structural protein is heavily cross-linked by disulphide bonds. Which protein is this?
α-Keratin is very rich in cysteine, whose disulphide bridges give hair and nails strength. Collagen is rich in glycine and proline instead.
Which is the most basic (first) level of DNA packaging in eukaryotic chromatin?
DNA wraps about 1.7 turns around a histone octamer to form a nucleosome; nucleosomes then coil into the 30-nm fibre and higher-order loops.
A serum sample left in a boiling water bath turns cloudy as its proteins precipitate. This is because heat:
Heat denaturation breaks hydrogen and hydrophobic interactions, unfolding the protein so it aggregates. The primary sequence (peptide bonds) stays intact.
Triglycerides made in the liver are exported to muscle and adipose tissue mainly in:
Very-low-density lipoproteins carry endogenous triglyceride from the liver. Chylomicrons carry dietary (exogenous) fat from the gut.
Which of these is an amino acid that the human body can make for itself?
Proline is formed from glutamate, so it is non-essential. Leucine, lysine and tryptophan must come from the diet.
Gram for gram, complete oxidation of which fuel releases the most energy?
Fat yields about 9 kcal/g because its carbons are highly reduced; carbohydrates and protein give about 4 kcal/g.
A preterm infant with respiratory distress lacks dipalmitoylphosphatidylcholine in the alveoli. Chemically, this surfactant is a:
Dipalmitoyl lecithin is glycerol esterified with two palmitates and phosphocholine. It lowers alveolar surface tension; cerebrosides and gangliosides are sphingolipids.
HIV copies its RNA genome into DNA using an enzyme best described as:
Reverse transcriptase reads an RNA template and makes complementary DNA, the basis of RT-PCR and antiretroviral targeting.
An infant fed only cow's milk for a long period is most at risk of lacking which vitamin?
Milk is a good source of vitamin A, riboflavin and B12 but provides very little ascorbic acid; iron is also deficient.
Glucocerebroside accumulates in macrophages in Gaucher disease. Which enzyme is deficient?
Glucocerebrosidase normally removes glucose from glucosylceramide. Hexosaminidase A deficiency causes Tay–Sachs; sphingomyelinase deficiency causes Niemann–Pick.
Glycogen breakdown in skeletal muscle cannot release free glucose into the blood because muscle lacks:
Only liver, kidney and intestine have glucose-6-phosphatase. Muscle uses its glucose-6-phosphate for its own glycolysis.
The lecithin/sphingomyelin ratio in amniotic fluid is measured to assess:
Surfactant lecithin rises sharply late in gestation; a ratio of 2 or more suggests low risk of neonatal respiratory distress syndrome.
An oil with a high iodine number is characterised by:
The iodine number is the grams of iodine absorbed per 100 g of fat, reflecting unsaturation. Rancidity is assessed by acid or peroxide values.
A 39-amino-acid peptide from the anterior pituitary that drives cortisol secretion by the adrenal cortex is:
ACTH is a 39-residue peptide cleaved from POMC in anterior pituitary corticotrophs. Glucagon (29 residues) and insulin are pancreatic; oxytocin is a posterior pituitary nonapeptide.
Compared with normal plasma, which intravenous solution is hypertonic?
3% saline has roughly three times the osmolality of plasma. 0.9% saline is isotonic, while 0.45% saline and water are hypotonic and would cause red cells to swell.
The first complete amino acid sequence of a protein, insulin, was determined by:
Sanger sequenced insulin using end-group labelling (FDNB) and fragment overlap. Edman later devised stepwise N-terminal degradation; Pauling described the α-helix.
A random urine sample from a healthy adult on a mixed diet typically has a pH of about:
Urine pH normally ranges 4.5–8.0 and averages about 6.0 because the kidney excretes the daily acid load. A pH of 9 suggests an old sample with urease-producing bacteria.
Digoxin, a drug often monitored in the laboratory, belongs to which chemical class?
Digoxin is a steroid linked to sugar residues through glycosidic bonds, i.e. a cardiac glycoside from foxglove. Its narrow therapeutic range requires TDM.