Biochem Answers

BIOCHEMISTRY REVALIDA 1. In Rheumatoid Arthritis, an autoimmune disease, a) specificity b) diversity c) memory d) discrimination of self from non-self e) self - ________________ 2. While commuting to school you were exposed to a fellow passenger who kept on coughing in transit. This was the 1st time you were exposed to the bacteria that caused the passenger’s cough. Which complement pathway functions in this instance? a) Mannose-binding Lectin b) Classical c) Alternative d) None of the above 3. After eating shrimps, you developed an immediate hypersensitivity reaction. This is brought about by the following: a) humoral immunity b) cell-mediated immunity c) natural immunity d) all of the above 4. the following are basic structural charcteristics of DNA, except a) double stranded, with strands wound around each other b) strands run anti-parallel with respect to the other strand c) bases on the outside while phosphates and sugar on the inside d) hydrogen bonding occurs between bases of both sides 5. The following are examples of Chargaff’s rule except a) Investigators found blood splattered all over a possible crime scene, so samples were collected and tested to establish if it’s human in origin b) The DNA left behind by a missing girl whose photo was digitally aged was matched with that of the woman who looked similar to the photo c) DNA were tested from ancient remains where mixed non-human and human were found to segregate which were human and which were not d) When studying the composition of unknown DNA, you found that A is 20%, you can deduce that T is also 20% while G and C are 30% each

6. Steatorrhea characterized by clay-colored stools with increased amount of digested but unabsorbed fats is due to; a) deficiency of pancreatic juice b) deficiency of bile c) lack of gastric juice d) defect in intestinal mucosa 7. In the treatment of inborn errors of urea synthesis, the potential build-up of ammonia is prevented by a) limiting the ingestion of proteins b) giving levulose to promote excretion of NH3 in the stools c) giving antibiotics to kill NHs-producing bacteria d) all of the above e) a and c 8. How does vitamin B6 deficiency affect the kynurenine-anthranilate pathway? a) Trp will not be converted to kynurenine b) Hydroxyanthranilate will not be converted to niacin c) Kynurenine will not be converted to hydroxykynurenine d) Hydroxykynurenine will not be converted to hydroxyxanthranilate 9. Mental retardation, eye and skin lesions are manifestations of the disease a) PKU b) Hartnup disease c) Richner-hanhart syndrome d) Homocystinuria 10. Manifestation of riboflavin deficiency a) scaly and greasy eruptions around nose and mouth b) painful fissures at the angle of the mouth c) glossitis d) acrodynia in rats 11. carbon monoxide and cyanide inhibit ATP production by: a) decreasing the overall production of the electron transport chain b) uncoupling oxidative phosphorylation c) disturbing proton gradient across the mitochondrial membrane d) binding to cytochrome oxidase of the respiratory chain e) C and D are correct 12. All of the following describe skin lesions of vitamin d deficiency, a) black tongue b) casal’s necklace c) d)

13. Nitrogen enters the urea cycle as: a) NH4 and aspartate b) Glutamate and NH3 c) Ornithine and NH3+ d) Ornithine and citrulline 14. N-acetylglutamate specifically activates this enzyme a) ornithine transcabamylase b) carbamoyl phosphate synthetase I c) arginase d) glutamate dehydrogenase 15. Products of trans amination a) keto-acid b) amino acid c) ammonia d) all of the above e) a and b only 16. enzymes involved in oxidative deamination a) amino acid dehydrase b) amino acid desulfydrase c) L-amino acid oxidase d) All of the above e) A and b 17. In creatine synthesis, the last amino acid to be added is: a) methionine b) glycine c) arginine d) glutamic acid 18. True about intracellular protein degradation a) tissues undergoing major structural rearrangement have high mean rates of ______ b) the rate of protein degradation in a cell varies with its nutritional and hormonal level c) extracellular, membrane-associated and long-lived intracellular protein are degraded in lysosomes by ATPindependent proteins d) all are true e) B and C only are true 19. The N-terminal amino acid of glutathione is a) Glycine b) Cysteine c) Arginine d) Glutamic Acid 20. True regarding a neutral alpha-L-amino acid a) its isoelectric points is around pH 6.0 b) it is considered to be amphoteric

c) it is a mono-amino, monocarboxylic aminoacid d) all of the above e) only B and C are true 21. A protein, whe subjected to denaturation will exhibit the following changes: a) the peptide bond linking its component amino acids will be cleaved b) the hydrogen bonds exsisting between its peptide bonds will be out c) the disulfide bridges between cysteine residues will be cleaved d) all of the above e) only B and C 22. if you want to determine what is the last amino acid in a peptide chain, what reaction will you perform a) reaction with cyanogen bromide b) reaction with lithium borohydride c) reaction with deacetyl chloride d) none of the above 23. This can be a limiting amino acid a) glutamine b) asparagine c) typtophan d) all of the above 24. this amino acid can be synthesized both from essential and non-essential amino acid a) tyrosine b) glycine c) alanine d) serine 25. all of the following are committed enzymes, EXCEPT a) Phosphofructokinase b) Glucose-6-PO4 dehydrogenase c) Citrate synthase d) Pyruvate kinase 26. The r-group of amino acid can form an ionic bond with the R group of aspartic acid a) Threonine b) Lysine c) Glutamic Acid d) All of the above e) A and C only 27. The succeptibility of a protein to degradation is very rapid if it contains a) PEST sequence b) KFERQ sequence c) N-terminal Met residue d) N-terminal Ser residue

28. Given amino acid with the following pK values : pK1 = 2.2, pK2 = 9.6 pKr = 4.0 The amino acid is most likely to be a) Valine b) Arginine c) Apspartic Acid d) Asparagine 29. abnormal proteins that tend to accumulate in our body can be eliminated thru a) excretion in the stool b) excretion in the urine c) intracellular degradation d) all of the above

30. Glutamate dehydrogenase is the most active enzyme involved in a) Transamination b) Oxidaive deamination c) Non-oxidative deamination d) Decarboxylation 31. This form of folic acid provides carbon no. 2 of the purine nucleus a) N10-formyl THFA b) N10-hydroxymethyl THFA c) N5-methylene THFA d) N5-formomino THFA 32. functions of vitamin C a) coenzyme in collagen formation b) hydroxylation of steroid in adrenal cortex c) potentiates immune system d) all of the above e) a and c only 33. the most pronounced effect of folate deficiency a) inhibition of protein synthesis b) inhibition of DNA synthesis c) inhibition of ATP synthesis d) all of the above 34. this vitamin is now added to some bacon and other food to help promote the

________ of nitrosamines even before they enter the body a) Vit A b) Vit E c) Vit C d) Thiamine 35. Factors that affect the absorption and transport of Vitamin A a) low fat intake b) low protein intake c) measles, chicken pox, URTI d) all of the above e) A and B only 36. The single most important factor that determines the requirements for vitamin E a) exposure to air pollutants b) axposure to radicals formed in foods c) intake of PUFA d) intake of high cholesterol food 37. Methotrexate inhibits this enzyme a) thymidykate synthetase b) ribonucleotide reductase c) dihydrofolate reductase d) thioredovin reductase 38. Vitamin K is a component of a) cytochromes b) coenzyme A c) ubiquotone (?) d) all of the above 39. threonine is referred to as the “morale vitamin” because a) it is important in carbohydrate metabolism b) it is important in ATP generation c) it is important in metabolism of nerve tissues d) all of the above