Biochemistry Mock Boards Examination(2)

Biochemistry Mock Boards Examination

1. Which of the following nitrogenous base is found only in DNA? a. Cytosine b. thymine

c. adenine

d. guanine

2. Which is not used as a building block of nucleic acids? a. Xanthuine

c. nitrogenous base

b. Ribose or deoxyribose d. phosphoric acid 3. One of the following is a nbucleoside a. AMP

b. adenylic acid

c. cGMP

d. thymidine

4. Which is true of the Watson and Crick model of DNA? a. Presence of major and minor groove b. Made up of 12 base pairs per turn of the helix c. The two chains are left-handed helix d. The two chains are parallel to each other with some polarity 5. What is the highest level of structural organization of DNA? a. Bare double-helix DNA

c. nucleosome

b. Chromosome

d. supercoiled nucleosome

6. N3 and N9 of the purine ring is derived from: a. Glutamine

b. aspartate c. glycine

d. formylFH4

7. N3 of the pyrimidine ring is derived from: a. Glycine

b. asparagine

c. glutamine d. aspartate

8. What is the end-product of pyrimidine metabolism in man? a. Allantoin b. uric acid

c. urea

d. beta-alanine

9. Deficiency of this enzyme will cause immunodeficiency of B-calle and T-cells. a. HGPRTaase b. APRTase

c. adenosine deaminase d. IMP dehydrogenase

10.The rate-limiting enzyme in the de novo synthesis of pyrimidine nucleotide a. Carbamoyl phosphate synthetase II phosphorylase

c. purine nucleoside

b. PRPP amidotransferase

d. orotidylate decarboxylase

11.Dihydrofolate reductase is inhibited by: a. Thymidylate synthase

c. allopurinol

b. Amethopterin

d. mefenamic acid

12.The first pyrimidine nucleotide to be synthesized is: a. Orotidylic acid

c. adenylic acid

b. Thymidylic acid

d. inosinic acid

13.This enzyme unwinds short segments of DNA during replication: a. Helicase

c. DNA ligase

b. Primase

d. topoisomerase

14.The leading strand replicase in eukaryotic DNA replication is” a. DNA polymerase alpha b. DNA polymerase beta

c. DNA polymerase gamma d. DNA polymerase delta

15.The quinolone group of antibiotics will inhibit this enzyme of replication: a. DNA gyrase

c. DNA ligase

b. DNA pol I

d. DNA pol III

16.Which is true regarding the elongation phase of replication? a. Bidirectional b. Okazaki fragments are formed in the leading strand c. Leading strand is replicated discontinuously d. Major enzyme involved is DNA polymerase I 17.All of the following are needed during replication, EXCEPT: a. DNA template

c. RNA primer

b. dATP, dGTP, dTTP, dCTP

d. reverse transcriptase

18.Transfer RNA in mammalian cells is synthesized by: a. RNAP I

b. RNAP II

c. RNAP III

d. RNAP IV

19.This subunit of RNA polymerase helps the enzyme in locating the promoter site of the gene a. Alpha

b. beta

c. gamma

d. sigma

20.Removal of introns and splicing of exons occur during this step of transcription a. Recognition of promoter site c. elongation b. Initiation

d. posttranscriptional modification

21.RNA polymerase are differentiated from one another by: a. Amanitin (?)

b. pyrazinamide

c. rifampicin d. ethambutol

22.The anticodon is present in this final product of transcription a. tRNA

b. mRNA

c. hnRNA

d. rRNA

23.The initiating amino acid in prokaryotes is: a. Formylmethionine

b. threonine c. methionine

d. glutamine

24.The translocation step during elongation of polypeptide chain is inhibited by a. Streptomycin

b. tetracyclie

c. chloramphenicol d. erythromycin

25.Which part of mRNA is recognized by tRNA? a. Amino acid arm

c. codon

b. Enzyme recognition site

d. ribosome recognition site

26.What is the major enzyme in translation? a. Aminoacyl tRNA synthetase

c. translocase

b. Peptidyl transferase

d. elongase

27.Which of the following posttranscriptional modification is involved in the conversion of preproinsulin to proinsulin? a. Removal of leader peptide b. Glycosylation

c. carboxylation d. phosphorylation

28.The fact that a codon specifies only one amino acid means that the genetic code is: a. Degenerate commaless

b. unambiguous

c. universal d.

29.There is no signal for the end of one codon and the beginning of the next codon which means the genetic code is: a. Degenerate

b. nonoverlapping c. universal d. commaless

30.Proteins with garbled amino acid sequence are produced when there is: a. Transition point mutation

c. missense mutation

b. Transversionpoint mutation

d. insertion frameshift mutation

31.When guanine is substituted by adenine in the genetic code, that is: a. Transition b. partially acceptable mutation c. transversion unacceptable mutation

d.

32.The appearance of a stop codon during mutation is a form of: a. Nonsense mutation

c. acceptable missense mutation

b. Partially acceptable missense

d. unacceptable missense mutation

33.Which of the following is an omega-6 fatty acid? a. Eicosapentaenoic acid

c. alpha-linoleic acid

b. Docosahexaenoic acid

d. arachidonic acid

34.Which is true of saponification reaction of triacylglycerol? a. Reaction is reversible

c. sodium or potassium soap is formed

b. Also called ordinary hydrolysis

d. products are insoluble in water

35.Which of the following is true of phosphatidyl ethanolamine a. A plasmalogen b. Also called cephalin

c. structural backbone is sphingosine d. ceremide is the parent compound

36.One of the following glycolipid contains sialic acid, hexoses and hexosamines a. Ganglioside

b. cerebroside

c. globoside d. sulfatide

37.Which of the following steroids is correctly classified:

a. Cholesterol is a C-27 steroid with 8 carbons in the side chain b. Testosterone is a C-24 steroid with 5 carbons in the side chain c. Cholic acid is a C-21 steroid with 2 carbons in the side chain d. Cortisol is a C-19 steroid with no side chain 38.Which of the following will NOT cause steatorrhea? a. Deficiency of pancreatic lipase

c. nontropical sprue

b. Deficiency of gastric lipase

d. deficiency of bile salts

39.Which of the following is true of extramitochondrial lipogenesis a. Requires acyl carrier protein b. Committed step is the formation of malonyl-ACP c. An elongation pathway d. End-product of the pathway is stearic acid 40.What is the source of glycerol 3-phosphate in the adipose tissue and muscle? a. Glycerokinase reaction

c. free glycerol

b. Glyceraldehyde 3-phosphate d. dihydroxyacetone phosphate 41.Which one is NOT needed for the activation of hormone-sensitive TAG lipase? a. Protein kinase

b. ATP

c. cAMP

d. insulin

42.What is the initial reactant in the de novo synthesis off phosphoglycerides a. CDP-diacylglycerol d. plasmalogen

b. phosphatidic acid

c. 1,2-diacylglycerol

43.Gaucher’s disease is due to the deficiency of this enzyme: a. Glucocerebrosidase

c. aryl sulfatase A

b. Hexosaminidase A

d. sphingomyelinase

44.The committed step in beta oxidation of fatty acid is catalyzed by: a. Fatty acyl CoA synthetase

c. carnitine-palmitoyl CoA transferase I

b. Acyl CoA dehydrogenase

d. acyl-carnitine translocase

45.The first ketone body to be synthesized is:

a. HMG-CoA

c. acetone

b. Acetoacetate

d. 3-hydroxybutyrate

46.The committed step in cholesterol synthesis involves the formation of: a. Mevalonate

c. squalene

b. Isopenteyl pyrophosphate

d. lanosterol

47.The formation of this intermediate metabolite is the most expensive tage in cholesterol synthesis a. Mevalonate pyrophosphate

b. lanosterol

c. squalene d. isopentyl

48.Which of the following lipoproteins is the substrate of extrahepatic lipoprotein lipase? a. Chylomicron remnant b. VLDL

c. LDL

d. HDL

49.The LCAT reaction takes place in which lipoprotein? a. Chylomicron

b. alpha lipoproteinc. prebeta lipoprot d. beta lipoprot

50.Which statement best describe allosteric enzymes? a. They are not usually controlled by feedback inhibition b. Effectors may enhance or inhibit substrate binding c. The regulatory site may also be the catalytic site d. Michaelis-Menten Kinetics describe their activity 51.Which statement does not describe the active site site? a. Small relative to the entire enzyme b. 2 dimensional in structure c. Usually a cleft or crevice d. Binds substrates by weak interactions 52.A low Km of an enzyme for its substrate means a. Low affinity of the enzyme for its substrate b. Low specificity of the enzyme for its substrate

c. Strong affinity of the enzyme for its substrate d. Shows a sigmoid curve 53.This is a change in entropy, that part of enthalpy which is not available to do work a. ∆S

b. ∆G

c. ∆H

d. ∆T

54.Which of the following will inhibit complex I of the ETC a. Hydrogen cyanide b. Carbon monoxide c. Hydrogen sulfide d. Amytal 55.Which of the following has a lower free energy of hydrolysis than ATP? a. Creatine phosphate b. Pyrophosphate c. Phosphoenolpyruvate d. Carbamyl phosphate 56.This is what we call electrochemical potential a. Standard free energy charge b. Electrochemical gradient c. Proton motive force d. Energy of activation 57.Most potent antioxidant that neutralizes reactive oxygen spicies in the cell membrane a. Vitamin E b. Vitamin A c. Ascorbic acid d. Beta carotene 58.Form of vitamin A that is present in rhodopsin

a. Retinoic acid b. Retinal c. Retinol d. Rotenone 59.Reaction catalyzed by vitamin K during the maturation of prothrombin ___ of glutamate a. Methylation b. Sulfation c. Acetytlation d. Gamma-carboxylation 60.Which is involved in carboxylation reaction a. Biotin b. Thiamine c. Niacin d. Riboflavin 61.Deficiency of this vitamin will cause pernicious anemia a. Pyridoxine b. Folic acid c. Ascorbic acid d. Cobalamin 62.This vitamin is a component of acyl carrier protein and coenzyme A a. Vit B1 b. Vit B5 c. Vit B3 d. Vit B12 63.This derivative of Vitamin D is synthesized in the kidney and primarily involved in calcium metabolism

a. 25-hydroxycholecalciferol b. 1,125-dihydroxycholecalciferol c. 1-hydroxycholecalciferol d. 24,25-dihydroxycholecalciferol 64.Microcytic, hypochromic anemia is due to the deficiency of a. Cyanocobalamin b. Folic acid c. Pyridoxine d. Riboflavin 65.The coenzyme derivative of this vitamin serves as a carrier of one-carbon atom a. Retinol b. Phylloquinone c. Folic acid d. Tocopherol 66.Deficiency of this vitamin will cause hemorrhagic disease of the newborn a. Tocopherol b. Menaquinone c. Biotin d. Cholecalciferol 67.The two monosaccharide units that make up sucrose are a. Glucose and galactose b. Manose nad glucose c. Glucose and fructose d. Fructose and galactose 68.Which of the following polysaccharides is NOT a polymer of glucose a. Inulin

b. Glycogen c. Cellulose d. Dextran 69.Two sugars that differ from one another in the configuration around one asymmetric carbon atom are called a. Optical isomers b. Diastereoisomers c. Anomers d. Epimers 70.Which of the following mucopolysaccharides is made up of alternating units of D-glucuronic acid and N-acetylglucosamine a. Chondroitin sulfate b. Hyaluronic acid c. Heparin keratin sulfate 75. Which of the following is used as a test for the presence of reducing sugars in the urine a. Benedicts test b. Salkowskis test c. Gmelins test d. Iodone test 76. The most important carbohydrate-digesting enzyme in the GIT is a. ptyalin b. amylopsin c. lactase d. maltase 77. Which is true of hexokinase a. specific for glucose

b. inhibited by glucose 6 phosphate c. high Km for glucose d. found only in the liver 78. Rate-limiting step in glycolysis involves the formation of a. glucose 6 phosphate b. fructose 6 phosphate c. fructose 1,6- diphosphate d. 1,3-bisphosphoglycerate 79. The pyruvate dehydrogenase reaction links glycolysis to a. Krebs cycle b. pentose phosphate pathway c. gluconeogenesis d. glycogenesis 80. The committed step in the Krebs cycle is catalyzed by a. alpha-ketoglutarate dehydrogenase b. malate dehydrogenase c. succinate dehydrogenase d. citrate synthase 81. All of the following are substrates for gluconeogenesis, EXCEPT a. amino acids b. lactate c. fatty acid d. glycerol 82. Which of the following enzymes is NOT used to bypass the irreversible steps in glycolysis during gluconeogenesis a. glucose 6 phosphate b. pyruvate decarboxylase

c. fructose 1,6-bisphosphatase d. phosphoenolpyruvate carboxylase 83. What is the covalently modulated regulatory enzyme in glycogenesis a. glycogen synthase b. phosphoglucomutase c. branching enzyme d. UDP-glucose pyrophosphorylase 84. Second messenger that is used to regulate glycogenesis and glycogenolysis a. inositol trisphosphate b. cGMP c. calcium d. cAMP 85. Enzyme that is deficient in Von Gierke’s disease a. glycogen synthase b. phophoglucomutase c. glycogen phosphorylase d. glucose 6-phosphatase 86. The committed enzyme in the hexose monophosphate shunt a. transketolase b. transaldolase c. glucose 6-phosphate dehydrogenase d. phosphohexose isomerase 87. Functions of the HMP shunt, EXCEPT a. generates ATP b. generates ribose 5-phosphate c. formation of NADPH

d. interconversion of sugars 88. Which of the following proteins serve as carrier of bilirubin, fatty acids, and drugs in the blood a. protamine b. scleroprotein c. histone d. albumin 89. Which amino acids contain the indole group and absorbs ultraviolet light a. serine b. tryptophan c. isoleucine d. asparagine 90. Which amino acid is negatively charge at physiologic pH a. alanine b. arginine c. aspartae d. threonine 91. Shape or confirmation refer to this level of structural organization of proteins a. primary b. secondary c. tertiary d. quaternary 92. This level of structural organization of protein is stabilized only by hydrogen bonds formed between peptide bonds a. primary b. secondary c. tertiary

d. quaternary 93. Which is NOT formed during transamination reaction a. free ammonia b. pyridoxine phosphate c. new amino acid d. new alpha-keto acid 94. What is the most active oxidative deamination enzyme a. amino acid dehydrase b. D-amino acid oxidase c. amino acid desulfhydrase d. glutamate dehydrogenase 95. Transamination of alpha-ketoglutarate produces this amino acid a. phenylalanine b. aspartic acid c. glutamic acid d. alanine 96. Which amino acid is purely ketogenic a. proline b. leucine c. isoleucine d. threonine 97. Carnitine is syntheisized from this amino acid a. tryptophan b. histidine c. lysine d. valine

98. This nonprotein nitrogenous substance is derived from histidine a. serotonin b. glutathione c. niacin d. histamine 99. What is the most important role of amino acids in our body? a. used for synthesis of nonprotein nitrogenous tissue constituents b. used ofr synthesis of essential amino acids c. catabolism of the carbon and nitrogen group of amino acids d. building blocks for synthesis of tissue proteins 100. The major means by which the body detoxifies ammonia involves the formation of a. asparagine b. glutamate c. glutamine d. urea

Guys, sorry if this is uber late and for not picking up my phone for the last days. Literally na iniiiwan ko sa bahay yung telepono ko. Si lolo nasa hospital naka-tubo. Matter of time na lang. Baka mag-arrest na. Sorry.