National Licensure Examination for Veterinarians (NLEV) · Nepal · Nepal Veterinary Council (NVC Act 2055 BS)
Original practice questions written to the published syllabus · not past papersBiomolecules, enzymes and the metabolic pathways that turn feed into energy, milk, meat and eggs, including the ruminant's special dependence on volatile fatty acids and gluconeogenesis.
In the exams: ICAR AICE-JRF core group 08; ICAR AIEEA-PG 12 (Veterinary Biochemistry); China basic paper 12
How our questions for National Licensure Examination for Veterinarians spread across the units of Veterinary Biochemistry. Difficulty: 35 easy, 6 medium, 0 hard.
| Biochemical laboratory techniques | 7 | |
| Enzymes and enzyme kinetics | 4 | |
| Nucleic acids | 4 | |
| Minerals: biochemical roles | 4 | |
| Biomolecules and their interactions | 3 | |
| Carbohydrate metabolism | 3 | |
| Lipid metabolism | 3 | |
| Protein and amino-acid metabolism | 3 | |
| Hormones | 3 | |
| Ruminant metabolism: volatile fatty acids, gluconeogenesis and ketogenesis | 3 | |
| Vitamins: biochemical roles | 2 | |
| Cell signalling | 2 |
Choose an answer, then open the working. Each explanation says why the right answer is right and why the others are not.
Lactose, the sugar of milk, is made of which two monosaccharides?
B. Galactose and glucose
Lactose is galactose beta-1,4 glucose. Glucose plus fructose is sucrose, and two glucose units form maltose.
Further reading: Nelson DL, Cox MM, Lehninger Principles of Biochemistry, 8th ed.
In a Lineweaver-Burk plot, lines for an enzyme with and without a competitive inhibitor:
D. intersect on the y-axis
Competitive inhibitors leave Vmax (and so 1/Vmax, the y-intercept) unchanged while increasing the slope. Intersection on the x-axis is the pure non-competitive pattern; parallel lines indicate uncompetitive inhibition.
Further reading: Nelson DL, Cox MM, Lehninger Principles of Biochemistry, 8th ed.
Organophosphate insecticides inhibit acetylcholinesterase by:
B. phosphorylating the active-site serine, an effectively irreversible inhibition
Organophosphates covalently phosphorylate the catalytic serine; activity returns only as new enzyme is made or if oximes reactivate it before ageing. Carbamates bind in a slowly reversible way.
Further reading: Gupta RC (ed), Veterinary Toxicology, 3rd ed.
Which enzyme is the main rate-controlling step of glycolysis?
C. Phosphofructokinase-1
PFK-1 catalyses an irreversible step and is allosterically activated by AMP and fructose-2,6-bisphosphate and inhibited by ATP and citrate. Aldolase, isomerase and enolase catalyse near-equilibrium steps.
Further reading: Nelson DL, Cox MM, Lehninger Principles of Biochemistry, 8th ed.
Birds excrete most of their waste nitrogen as:
D. uric acid
Birds are uricotelic: they lack a functional hepatic urea cycle and make uric acid via purine synthesis, which is why arginine is essential in their diet. Mammals are ureotelic; many aquatic animals are ammonotelic.
Further reading: Nelson DL, Cox MM, Lehninger Principles of Biochemistry, 8th ed.
Which enzyme converts hypoxanthine and xanthine to uric acid?
B. Xanthine oxidase
Xanthine oxidase, a molybdenum enzyme inhibited by allopurinol, makes uric acid. Uricase oxidises uric acid to allantoin; HGPRT salvages purine bases.
Further reading: Nelson DL, Cox MM, Lehninger Principles of Biochemistry, 8th ed.
Thiamine pyrophosphate is the coenzyme of which enzyme?
A. Transketolase
TPP serves transketolase, pyruvate dehydrogenase and alpha-ketoglutarate dehydrogenase. ALT uses pyridoxal phosphate, acetyl-CoA carboxylase uses biotin, and the mutase uses vitamin B12.
Further reading: Nelson DL, Cox MM, Lehninger Principles of Biochemistry, 8th ed.
Which of the following is a direct metabolic effect of insulin?
C. Inhibition of lipolysis
Insulin is the hormone of the fed state: it inhibits lipolysis, gluconeogenesis and ketogenesis and promotes glycogen synthesis. The other three are effects of glucagon and catecholamines.
Further reading: Nelson DL, Cox MM, Lehninger Principles of Biochemistry, 8th ed.
Which second messenger is produced when glucagon binds its receptor on hepatocytes?
B. Cyclic AMP
The glucagon receptor couples to Gs, activating adenylyl cyclase to make cyclic AMP, which activates protein kinase A. IP3 and DAG come from Gq-coupled phospholipase C.
Further reading: Nelson DL, Cox MM, Lehninger Principles of Biochemistry, 8th ed.
Which tube is preferred when glucose measurement must be delayed?
A. Sodium fluoride-potassium oxalate
Fluoride inhibits enolase, stopping glycolysis by blood cells that would otherwise lower glucose. Unseparated plain or heparinised samples lose glucose with time; citrate is for coagulation tests.
Further reading: Stockham SL, Scott MA, Fundamentals of Veterinary Clinical Pathology, 2nd ed.
Ten here, 41 in the app. The Laisha app has every practice question we have written to National Licensure Examination for Veterinarians in this subject, marked as you go, with timed papers, a jump-to-unanswered list and a certificate when you pass at 70 per cent.
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