Biochem Final All MCQs PDF

Which of the following statements about phenylalanine degradation are TRUE? 1) phenylalanine hydroxylase uses ascorbic acid as a cofactor 2) phenylalanine hydroxylase uses tetrahydrobiopterin as a cofactor 3) phenylalanine hydroxylase uses NADPH as a cofactor 4) a deficiency of homogentisate oxidase...

Which of the following statements about phenylalanine degradation are TRUE? 1) phenylalanine hydroxylase uses ascorbic acid as a cofactor 2) phenylalanine hydroxylase uses tetrahydrobiopterin as a cofactor 3) phenylalanine hydroxylase uses NADPH as a cofactor 4) a deficiency of homogentisate oxidase causes tyrosinemia type II 5) a deficiency of phenylalanine hydroxylase results in higher concentration of phenylpyruvate, phenyllactate and phenylacetate (2 βαθμοί) 2+4 1+5 2+5 1+4 3+4 2.Which statements concerning the anabolic processes are CORRECT? 1) they are processes of synthesis of cell-specific proteins and nucleic acids 2) they are processes of energy accumulation in microergic compounds 3) they are processes of oxidation of substrate molecules 4) they are processes of synthesis of ATP 5) they are reductive processes that “store” energy in the bonds of organic molecules (2 βαθμοί) 2+3 1+5 2+4 1+4 3+5 3.Which of the following hormones have a membrane receptor? 1) retinoic acid 2) ACTH 3) triiodothyronine 4) glucagon 5) calcitriol (2 βαθμοί) 3+4 2+4 2+5 1+3 1+5 4.Glycogen synthase is: (1 βαθμός) activated by glucagon inactive in its dephosphorylated form active in its dephosphorylated form inactivated by insulin activated by adrenalin 5.Which processes do NOT take place in the liver? 1) synthesis of chylomicrons 2) urea synthesis 3) synthesis of direct bilirubin 4) synthesis of bile acids 5) ammoniagenesis (2 βαθμοί) 1+5 2+4 1+3 3+4 2+5 6.What type of bond connects the nucleotides in DNA? (1 βαθμός) peptide hydrogen 3', 5'-phosphodiester N-glycosidic O-glycosidic 7.Which of the following statements about Krebs cycle is TRUE? 1) the regulatory enzymes are more active when the levels of ATP are high 2) the regulatory enzymes are less active when the levels of NADH are high 3) the cycle represents the final steps of oxidation of C-atoms that come from different substrates of biological oxidation 4) some of the intermediates of the cycle could be used for the synthesis of carbohydrates, lipids and proteins 5) the enzyme activities of the cycle are also found in the cytoplasm and various cell organelles (3 βαθμοί) 1+3+4 2+3+4 2+3+5 1+2+3 1+3+5 8.“Jaundice” is a condition of hyperbilirubinemia, the reasons for which could be: 1) intensive degradation of N-containing substrates in the cells 2) increased intake of N-containing molecules with food 3) abnormal breakdown of red blood cells (accelerated hemolysis) 4) obstruction of the biliary paths 5) defects in the enzyme UDP-glucuronyl transferase in the liver or other liver diseases (3 βαθμοί) 1+3+5 1+3+4 2+3+4 2+4+5 3+4+5 9.In тхе red blood cells (RBCs): 1) glycolysis can be performed either in aerobic or anaerobic conditions 2) the end product of glycolysis is always lactate 3) RBCs contain smaller amounts of 2,3-bisphosphoglycerate compared to the rest of the cells 4) the pentose phosphate pathway is of crucial importance for RBCs 5) reduced glutathione is of great importance for RBCs (3 βαθμοί) 2+3+4 2+3+5 2+4+5 1+2+3 1+3+4 10.The irreversible kinase reactions in glycolysis are catalyzed by: 1) hexokinase (glucokinase) 2) phosphoglycerate kinase 3) phosphofructokinase 4) phosphoenolpyruvate carboxykinase 5) pyruvate kinase (3 βαθμοί) 2+3+5 1+2+3 1+3+5 2+3+4 1+3+4 11.Which of the lipoprotein complexes transports exogenous (dietary) lipids, mainly TAG? (1 βαθμός)  LDL IDL HDL VLDL chylomicrons 12. Which of the following compounds does NOT derive from arginine: (1 βαθμός) polyamines nitric oxide (NO) ornithine ethanolamine creatine phosphate 13.The N-atom in carbamoyl phosphate, used for the pyrimidine ring synthesis, derives from: (1 βαθμός) ammonia (NH3) aspartate glutamate glutamine glycine 14.Which of the following statements about glycogen degradation in the liver is TRUE? (1 βαθμός) the regulatory enzyme is alpha-glucosidase the regulatory enzyme is the debranching enzyme it is the first mechanism for maintenance of the blood glucose level during fasting periods it is the mechanism for maintenance of the blood glucose level during long-term starvation it is a source of energy for the liver cells 15.Cholesterol: 1) is synthesized from Acetyl-CoA 2) is synthesized in the cytoplasm and the endoplasmic reticulum 3) the main regulatory enzyme of the synthesis is HMG-CoA synthase 4) is completely degraded in the liver 5) its synthesis is activated by insulin (3 βαθμοί) 1+2+3 1+2+5 2+3+4 1+3+4 2+3+5 16.Indicate the protein involved in the storage of iron in cells? (1 βαθμός) transferrin hepcidin divalent metal transporter 1 (DMT1) ferritin ceruloplasmin 17.Which of the following phospholipids contain sphingosine, one fatty acid, a phosphate group and choline? (1 βαθμός) sphingomyelins phosphatidylcholines phosphatidyl inositols ceramides glucocerebrosides 18.Which of the following mechanisms play role in ammonia detoxification? 1) glutamine biosynthesis in the brain 2) alanine biosynthesis in muscles 3) urea biosynthesis in muscles 4) urea biosynthesis in the kidneys 5) reductive amination of alpha-ketoglutarate (3 βαθμοί) 2+3+4 2+3+5 1+2+3 1+2+5 1+3+4 19.Which of the following shuttles is used in the synthesis of fatty acids? (1 βαθμός) citrate shuttle glycerol-3-phosphate shuttle malate shuttle carnitine shuttle shuttle of gluconeogenesis 20.Which of the following statements regarding the oxidation of fatty acids are CORRECT? 1) β-oxidation of fatty acids with an even number of carbon atoms, below 18 occurs in the mitochondria of the cells 2) all end products of the oxidation of fatty acids with an odd number of carbon atoms is Acetyl-CoA 3) oxidation of short-chain fatty acids occurs in peroxisomes 4) very long-chain fatty acids are oxidized in the cytoplasm 5) FADH2 and NADH are obtained in each of the cycles of β-oxidation in the mitochondria (2 βαθμοί) 1+3 2+5 3+4 2+4 1+5 21.Which of the following statements about the „de novo” synthesis of purines are TRUE? 1) the purine ring is built by adding atoms onto the basis of PRPP 2) phosphoribosyl is added to the already formed purine ring 3) a common metabolite of AMP and GMP synthesis is IMP 4) the synthesis begins with carbamoyl phosphate and aspartate 5) glycine and glutamine are involved in the synthesis (3 βαθμοί) 1+3+5 2+3+5 1+4+5 1+3+4 2+3+4 22.Which of the following statements about the regulation of the synthesis of fatty acids is TRUE? (1 βαθμός) the end product is an allosteric activator the main regulatory enzyme is the acyl synthase complex the synthesis is inhibited by insulin citrate activates the main regulatory enzyme the main regulatory enzyme is active in its phosphorylated form 23.How many ATP molecules are synthesized in the microsomal electron-transport chains? (1 βαθμός) two ATP molecules twelve ATP molecules one ATP molecule three ATP molecules no ATP molecules 24.Indicate the correct statement about receptors located on the cell membrane. (1 βαθμός)  after activation, the receptor is translocated to the nucleus, where it affects gene expression receptors with tyrosine kinase activity catalyze autophosphorylation and phosphorylation of other signaling molecules after activation, the receptor is transformed into a secondary messenger and transmits the information to a downstream component of the signaling pathway membrane receptors whose intracellular domains associate with G-proteins do not have an extracellular domains after activation, the receptor undergoes a process of "maturation" by cleavage of small peptides, which transmit the information to a downstream component of the signaling pathway 25.Which of the listed statements about osteoblasts are CORRECT? (2 βαθμοί) 1) their activation leads to bone resorption 2) their activation leads to bone formation 3) they activate osteoclasts 4) they suppress osteoclasts 5) they express RANK (the receptor activator of NF-kB) 2+4 1+3 2+5 1+4 2+3 26.The mitochondrial electron-transport chains: 1) exist as multienzyme complexes that create electro-chemical gradient, whose energy is used in ATP synthesis 2) are controlled by the ratio ubiquinone/ubiquinone.H2 3) consist of five (5) multienzyme complexes + an ATP-ase 4) are located in the inner mitochondrial membrane 5) require constant oxygen supply (3 βαθμοί) 1+4+5 1+3+4 2+3+4 3+4+5 1+2+3 27.Which of the statements concerning covalent modification of enzymes by phosphorylation /dephosphorylation are WRONG? 1) reversible phosphorylation/dephosphorylation is one of the ways to regulate enzyme activity 2) dephosphorylation is catalyzed by enzymes called serine/threonine protein kinases 3) phosphorylation is catalyzed by enzymes called protein phosphatases 4) the regulation by phosphorylation/dephosphorylation is under nervous and hormonal control 5) regulation is achieved by causing a slight conformational change affecting the active site of the enzyme (2 βαθμοί) 1+3 3+4 2+5 1+5 2+3 28.Which of the following statements regarding the synthesis and metabolism of lipoprotein complexes are TRUE? 1) pre-HDLs are synthesized only in the liver 2) VLDLs are metabolized by lipoprotein lipase 3) HDLs are produced as derivatives in VLDL metabolism 4) a high serum level of LDL increases the risk of myocardial infarction 5) HDLs carry cholesterol esters and clear up the excess of cholesterol from extrahepatic tissues (3 βαθμοί) 1+3+5 2+3+5 2+4+5 1+3+4 1+2+3 29.Which of the following molecules is the product of the reaction, catalyzed by the pyruvate dehydrogenase complex? (1 βαθμός) acetyl-CoA phosphoenolpyruvate  1,3-bisphosphoglycerate succinyl-CoA acyl-CoA 30.The synthesis of conjugated bile acids requires: 1) 7-α-hydroxylase 2) 25-hydroxylase 3) NADPH 4) glycine and taurine 5) citrate and malate (3 βαθμοί) 1+3+4 2+3+4 2+3+5 1+2+3 1+3+5 31.Heme synthesis occurs with high rate in: (1 βαθμός) erythrocytes kidneys pancreas liver brain 32.Which of the listed organs possess GLUT2 (glucose transporter 2) ? 1) liver 2) brain 3) muscles 4) pancreatic beta-cells 5) adipose tissue (2 βαθμοί) 2+5 1+4 2+4  1+3 3+4 33.Which of the following processes occur during long-term starvation? 1) glycogenolysis 2) ketogenesis 3) lipolysis 4) glycogenogenesis 5) gluconeogenesis (3 βαθμοί) 2+3+4 2+3+5 1+2+3 1+2+5 1+3+4 34.Vitamin D3: 1) is a cholesterol derivative 2) its active form is 1,25-dihydroxycholecalciferol (calcitriol) 3) is synthesized in the small intestine 4) its synthesis is activated by calcitonin 5) it inhibits the absorption of calcium in the small intestine (2 βαθμοί) 2+5 2+4 1+4 3+4 1+2 35.Which of the following compounds derive from tryptophan? 1) NAD+ 2) melanin 3) dopamine 4) serotonin 5) triiodothyronine (T3) (2 βαθμοί) 2+5 2+4  3+4 1+5 1+4 36.Which is the end product of purine nucleotide catabolism in humans? (1 βαθμός) creatinine urea xanthine ammonia uric acid 37.Which are the regulatory enzymes of pyrimidine biosynthesis? 1) carbamoyl phosphate synthetase II 2) ornithine transcarbamoylase 3) dihydroorotate dehydrogenase 4) aspartate transcarbamoylase 5) carbamoyl phosphate synthetase I (2 βαθμοί) 2+5 1+3 2+4 1+4 3+4 38.Which of the following enzymes release arachidonic acid from the membrane glycerophospholipids? (1 βαθμός) phospholipase D all phospholipases phospholipase A2 phospholipase A1 phospholipase C 39.Which of the following reactions require S-adenosyl methionine (SAM) as a donor of methyl groups? 1) dopamine to norepinephrine 2) norepinephrine to epinephrine 3) ethanolamine to choline 4) dUMP to dTMP 5) synthesis of purines (2 βαθμοί) 2+3 2+5 1+5 1+3 3+4 40.Which of the following statements about insulin and glucagon are TRUE? 1) insulin stimulates glucagon secretion 2) insulin is secreted in response to hyperglycemia 3) insulin is secreted in response to hypoglycemia 4) glucagon is an activator of gluconeogenesis and glycogen degradation in liver 5) insulin inhibits the pentose phosphate pathway (2 βαθμοί) 2+5 1+3 2+4 3+4 1+5 41.Complex I of the mitochondrial respiratory chains: 1) receives electrons from the reduced cofactors of the oxidative processes in the mitochondrial matrix 2) gives electrons to complex II of the respiratory chain 3) transports electrons towards ubiquinone 4) works as a proton pump in the outer mitochondrial membrane 5) co-works with cytochromes as its cofactors (2 βαθμοί) 1+4 1+3 2+4  1+2 1+5 42.Which of the following compounds are considered as “the key molecules” for the cell metabolism? 1) glyceraldehyde-3-phosphate 2) glucose-6-phosphate 3) acetyl-CoA 4) pyruvate 5) phosphoenolpyruvate (3 βαθμοί) 1+2+3 2+3+4 1+2+5 2+4+5 3+4+5 43.Porphyrias belong to a heterogenic group of diseases where: 1) the regulatory enzymes of heme synthesis “escape” their allosteric regulation 2) the reactions for detoxification of ammonia in the liver are impaired 3) there are deficiencies of enzymes included in heme synthesis pathway 4) there is a lack of heme and development of anemia 5) heme is overproduced (2 βαθμοί) 1+5 2+5 3+4 2+4 1+3 44.Which of the following redox-systems (redox pairs) belongs to the heme-containing compounds? (1 βαθμός) NAD+/HADH ubiquinone/ubiquinol FAD/FADH2 oxidized glutathione/reduced glutathione oxidized Cytochrome c / reduced Cytochrome c 45.Glutamate dehydrogenase: 1) catalyzes the oxidative deamination of glutamate to alpha- ketoglutarate using NAD+ as a cofactor 2) catalyzes the oxidative amination of glutamate using NAD+ as a cofactor 3) catalyzes the reductive amination of α-ketoglutarate to glutamate using NADPН as a cofactor 4) takes part in transdeamination (predeamination) 5) is allosterically activated by ATP and GTP (3 βαθμοί) 1+3+5 1+2+3 2+3+5 1+3+4 2+3+4 46.Galactose is: 1) metabolized mainly in the liver 2) metabolized mainly in the muscles 3) metabolized mainly in the small intestine 4) activated by phosphorylation mainly by galactokinase 5) activated by phosphorylation mainly by hexokinase (2 βαθμοί) 1+3 2+4 1+4 3+4 1+5 47.Indicate the correct answers about the structure of elastin. 1) it forms a triple helix 2) it is synthesized as a soluble monomer (tropoelastin) and some proline residues are hydroxylated 3) it is a glycoprotein as there is glycosylation of some of the hydroxyproline residues 4) tropoelastin contains hydroxylated lysine residues (OH-Lys) 5) it does not contain regularly the Gly-X-Y sequences in its chain (2 βαθμοί) 3+4 1+5 2+4 2+5 1+3 48.Ketogenesis is active during: 1) starvation 2) well-fed state 3) diabetes mellitus type I 4) normal insulin secretion 5) inhibited β-oxidation (2 βαθμοί) 1+3 1+5 3+4 2+5 2+4 49.Which of the following metabolites ARE NOT substrates or metabolites of the synthesis of cholesterol? 1) аcetyl-CoA 2) mevalonate 3) 3-hydroxy-3-methyl-glutaryl-CoA 4) malonyl-CoA 5) cholyl-CoA (2 βαθμοί) 2+4 1+5 4+5 1+3 3+4 50.Which of the following statements about iron metabolism is TRUE? (1 βαθμός) transferrin binds two ferrous (Fe2+) ions  hepcidin decreases serum iron by blocking ferroportin (IREG1) hephaestin and ceruloplasmin both reduce ferric (Fe3+) to ferrous (Fe2+) iron transferrin binds heme iron the major iron depot is the hemosiderin in the liver 51.Which is the correct statement? (1 βαθμός) unlike glycoproteins, proteoglycans contain carbohydrates in big proportion (up to 95%) proteoglycans are low molecular weight polycationic substances all types of glycosaminoglycans contain building blocks that are highly sulfated the carbohydrate part of glycoproteins is called "glycosaminoglycan" proteoglycans have important biological functions in the blood 52.Which of the following reactions from the urea cycle demand ATP? 1) arginine -> ornithine + urea 2) ornithine + carbamoyl phosphate -> citrulline 3) NH3 + CO2 -> carbamoyl phosphate 4) citrulline + aspartate -> argininosuccinate 5) argininosuccinate -> arginine + fumarate (2 βαθμοί) 2+4 1+3 1+5 2+5 3+4 53.Aldolase B is an enzyme in the catabolic pathway of: (1 βαθμός) triacylglycerols galactose purine bases fructose glucose 54.The absorption of vitamin B12 in the gastrointestinal tract (GIT) requires: (1 βαθμός) transcobalamin II phosphatidic acid transcobalamin I vitamin C intrinsic factor 55.Which is the main product of the digestion of the triacylglycerols (TAG) in the small intestine? (1 βαθμός) glycerol-3-phosphate 2-monoacylglycerol lysolecithin phosphatidic acid DAG 56.Which of the following molecules is a high-energy (macroergic) phosphate derivative? (1 βαθμός) dihydroxyacetone phosphate fructose-6-phosphate glycerol-3-phosphate 1,3-bisphosphoglycerate glucose-6-phosphate 57.Which of the following enzymes digests carbohydrates? (1 βαθμός) pepsin lipase alpha-amylase elastase phospholipase 58.The pentose phosphate pathway is: 1) localized in the mitochondria 2) localized in the cytosol 3) a source of NADPH for fatty acids biosynthesis 4) a source of NADPH for the respiratory chain 5) an alternative catabolic pathway for the degradation of glucose in muscles (2 βαθμοί) 1+3 1+5 2+4 2+3 3+5 59.Which of the following statements are TRUE? 1) the higher Km is, the lower the affinity of an enzyme to the substrate is 2) the higher Km is, the higher the affinity of an enzyme to the substrate is 3) the lower Vmax is, the higher the stability of enzyme-substrate complex is 4) the higher Vmax is, the higher the stability of enzyme-substrate complex is 5) Km is that concentration of the substrate, at which the initial velocity of the reaction is half of the Vmax (Vmax/2) (3 βαθμοί) 1+3+5 2+3+5 1+4+5 2+3+4 2+4+5 60.Which of the following statements about folic acid are TRUE? 1) its cofactor form is tetrahydrofolate 2) its cofactor form is dihydrofolate 3) it binds and carries C1-unit for synthesis of creatine phosphate 4) it binds and carries C1-units for the "de novo" synthesis of the purine ring 5) its deficiency causes hemolytic anaemia (2 βαθμοί) 1+3 1+4 2+4  3+5 2+5 61.The glycerol produced in lipolysis in adipose tissue: 1) is activated by glycerol kinase in the adipose tissue 2) is released into the bloodstream and then enters the muscles 3) is converted to glycerol-3-phosphate in the liver 4) is converted to glyceraldehyde-3-phosphate in the liver 5) is used for gluconeogenesis in the liver (2 βαθμοί) 3+5 2+5 1+4 2+4 1+3 62.The oxidation-reduction processes are catalyzed by enzymes having as cofactors some of the following compounds. Which are those cofactors? 1) folic acid derivatives (tetrahydrofolate) 2) vitamin B2 derivatives (FMN and FAD) 3) vitamin B3 derivatives (NAD+ and NADP+) 4) vitamin B6 derivatives (pyridoxal phosphate) 5) vitamin B12 derivatives (cobalamin) (2 βαθμοί) 1+4 3+5 2+4 1+2 2+3 63.Which vitamin is involved in the structure of Coenzyme A? (1 βαθμός) vitamin B1 (thiamine) vitamin B5 (pantothenic acid) vitamin B2 (riboflavin)  vitamin B12 (cobalamin) vitamin B3 (nicotinamide) 64.Which of the following statements regarding vitamin K are CORRECT? 1) vitamin K is a water-soluble vitamin 2) vitamin K is required for prolyl and lysyl hydroxylation of collagen 3) vitamin K is required for prolyl hydroxylation of some of the blood clotting factors 4) vitamin K is required for gamma-glutamyl carboxylation of some of the blood clotting factors 5) deficiency of vitamin K results in bleeding (2 βαθμοί) 3+5 4+5 1+2 1+4 2+4 65.Which of the following statements about anaerobic glycolysis in humans are TRUE? 1) occurs only in the cytosol 2) occurs in both cytosol and mitochondria 3) the final product of glucose oxidation is ethanol 4) the final product of glucose oxidation is lactate 5) produces only 2 moles ATP per 1 mole glucose (3 βαθμοί) 1+4+5 2+3+5 2+3+4 1+3+5 1+3+4 66.Which of the following statements about the synthesis of TAG are CORRECT? 1) the synthesis occurs only in the adipose tissue 2) in the adipose tissue glycerol-3-phosphate is obtained from dihydroxyacetone phosphate from glycolysis 3) in the small intestine there is a monoacylglycerol pathway 4) the enzyme glycerol-3-phosphate acyltransferase is active in its phosphorylated form 5) the synthesis is inhibited by insulin (2 βαθμοί) 2+3 1+4 2+5 1+3 2+4 67.Which properties are characteristic of the enzymes? 1) they have extremely high efficiency 2) they increase the activating energy of the reaction by formation of an enzyme-substrate complex 3) they have low substrate specificity 4) they act in large quantities 5) the activity and the synthesis of enzymes in the cells are regulated (2 βαθμοί) 3+4 1+5 2+5 1+3 2+4 68.Ketolysis occurs in: (1 βαθμός) the cytoplasm of extrahepatic tissues the mitochondria of hepatocytes the cytoplasm of hepatocytes the mitochondria of extrahepatic tissues the endoplasmic reticulum of neurons 69.Indicate the CORRECT statements about digestion and the secretory activity of the stomach. 1) the secretion of hydrochloric acid by the parietal cells of gastric glands requires the enzyme carbonic anhydrase 2) the cells of gastric glands secrete digestive enzymes that break down the glycosidic bonds of starch 3) the “intrinsic factor” activates the formation of pepsin by pepsinogen 4) the chief cells of gastric glands synthesize and secrete pepsinogen 5) the chief cells of gastric glands synthesize and secrete pepsin (2 βαθμοί) 3+4 1+4 2+5 2+4 1+3 70.Which of the following statements about the biochemical characteristics of blood clotting are TRUE? 1) zymogens of serine proteases are involved 2) the extrinsic and the intrinsic pathway of blood clotting are not linked 3) transglutaminase (factor XIII) destroys fibrin molecules 4) several of the blood clotting factors undergo maturation via Vitamin K-dependent carboxylation 5) thrombin is a tyrosine protein kinase (2 βαθμοί) 1+4 3+4 2+5 2+4 1+3 71.Acetyl-CoA is NOT a metabolite of: (1 βαθμός) ketogenesis glycolysis β-oxidation citric acid cycle synthesis of cholesterol 72.Which of the following statements about ATP are TRUE? 1) ATP is a macroergic compound with two pyrophosphate bonds 2) ATP gives away its energy only by hydrolysis of its second pyrophosphate bond 3) ATP synthesis is coupled with endergonic processes 4) ATP synthesis is coupled with exergonic processes 5) ATP is a cofactor of the enzymes catalyzing kinase reactions (3 βαθμοί) 2+4+5 1+4+5 1+2+3 2+3+5 1+2+4 73.Which of the following statements about hormones are TRUE? 1) hydrophobic hormones are transported across cell membranes and are recognized and bound by intracellular receptors 2) hydrophilic hormones do not enter the cells and are recognized and bound by cell membrane receptors 3) hydrophilic hormones are transported across the cell membrane and are recognized and bound by intracellular receptors 4) hydrophobic hormones do not enter cells and are recognized and bound by receptors on the cell membrane 5) are effective only at very high concentrations (2 βαθμοί) 2+5 3+4 1+2 1+5 2+4 74. Which of the following processes are free oxidation processes? 1) heat production 2) beta-oxidation of fatty acids 3) oxidation of xenobiotics with cytochrome P450 4) hydroxylation of tryptophan to 5-hydroxytryptophan 5) oxidation of alpha-keto acids (3 βαθμοί) 1+4+5 1+2+3 3+4+5  1+3+4 2+3+4 75.Please, indicate the CORRECT features of insulin signaling pathways. 1) insulin has a membrane receptor that does not have intrinsic tyrosine kinase activity and activates intracellular tyrosine kinases 2) insulin has a membrane receptor with intrinsic tyrosine kinase activity 3) insulin activates the phosphatidyl inositol-3-kinase (PI3K) pathway 4) a MAP kinase cascade is activated 5) JAK-STAT signaling pathway is activated (3 βαθμοί) 2+3+4 1+3+5 1+3+4 3+4+5 2+4+5 76.Which is the rate limiting step in the pentose phosphate pathway? (1 βαθμός) hexokinase reaction transaldolase reaction ribose-5-phosphate isomerase reaction transketolase reaction glucose-6-phosphate dehydrogenase reaction 77.Which of the following statements about eicosanoids are TRUE? 1) they are synthesized in glands 2) they have a very long half-life 3) they are signal molecules and trigger signal pathways 4) they are synthesized in many tissues and work as local hormones 5) they are synthesized in small concentrations (3 βαθμοί) 1+3+5 2+3+5 2+3+4 1+2+3 3+4+5 78.Which of the statements about the parathyroid hormone (PTH) are TRUE? 1) the low plasma Ca2+ level decreases PTH secretion 2) the low plasma Ca2+ level increases PTH secretion 3) it stimulates bone resorption and the release of Ca2+ in the extracellular space 4) binds to a serpentine receptor associated with G protein and activates the adenylyl cyclase pathway 5) inhibits the transcription of the enzyme 1-α-hydroxylase in the kidneys, necessary for the activation of vitamin D3 (3 βαθμοί) 1+3+5 1+3+4 2+3+4 2+4+5 3+4+5 79.Which of the listed statements about calcitonin is WRONG? (1 βαθμός) it is secreted by the C-cells of the thyroid gland it is secreted when the Ca2+ level in blood is low the triggered signaling pathway in target cells is cAMP-dependent promotes renal excretion of Ca2+ the receptors of calcitonin are G-protein associated membrane receptors 80.Which vitamins are needed as cofactors of the enzymes catalyzing the transformation of propionyl-CoA (one of the products of the oxidation of fatty acids with an odd number of carbon atoms)? 1) Vit. B9 2) Vit. PP (B3) 3) Vit. B6 4) Vit. B12 5) Vit. H (biotin) (2 βαθμοί) 1+5 2+4 1+3  4+5 3+4 81.Which of the following molecules DOES NOT serve as a precursor for gluconeogenesis? (1 βαθμός) lactate alanine methionine acetoacetate glycerol 82.Heme degradation is initiated by a substrate-inducible enzyme called: (1 βαθμός) heme oxygenase protoporphyrinogen oxidase heme reductase ferrochelatase UDP-glucuronyl transferase 83.Which of the following statements are CORRECT? 1) fibrous proteins have polypeptide chains arranged in long strands 2) globular proteins have polypeptide chains folded into a spherical shape 3) most enzymes and regulatory proteins are fibrous 4) globular proteins are insoluble in water 5) fibrous proteins are keratin, collagen and elastin (3 βαθμοί) 2+3+4 1+3+4 2+3+5 1+2+3 1+2+5 84.Which of the following biologically active compounds DO NOT derive from tyrosine? 1) thyroxine 2) melanin 3) melatonin 4) GABA 5) epinephrine (2 βαθμοί) 1+5 3+4 2+5 2+4 1+3 85.Which of the listed properties are valid for serum albumin? 1) it transports bile acids 2) it transports free fatty acids 3) its synthesis increases in liver diseases 4) it does not participate in the maintenance of the osmotic pressure of the plasma 5) it transports mainly peptide hormones (2 βαθμοί) 3+4 2+5 1+3 2+4 1+2 86.Gluconeogenesis occurs mainly in: 1) liver 2) brain 3) renal cortex 4) muscles 5) lungs (2 βαθμοί) 3+4 1+2 1+4 3+5 1+3 87.Which of the following statements about aminotransferases are TRUE? 1) they have NAD+ as a coenzyme 2) they have pyridoxal phosphate as a coenzyme 3) the serum ASAT concentration increases in myocardial infarction 4) the serum ASAT and ALAT concentrations decrease when a patient suffers from a liver disease (e.g. hepatitis) 5) they play an important role in the terminal detoxification of xenobiotics (2 βαθμοί) 2+5 1+5 2+3 1+4 3+4 88.The organic component of bone consists mainly of: (1 βαθμός) phosphate hydroxyapatite type I collagen calcium osteocalcin 89.Which is the correct and complete sequence of the reactions in the Krebs cycle? (1 βαθμός)  citrate synthase, aconitase, isocitrate dehydrogenase, α-ketoglutarate dehydrogenase, succinyl-CoA synthetase, succinate dehydrogenase, fumarase, malate dehydrogenase citrate synthase, aconitase, isocitrate dehydrogenase, α-ketoglutarate dehydrogenase, succinate dehydrogenase, succinyl-CoA synthetase, fumarase, malate dehydrogenase citrate synthase, α-ketoglutarate dehydrogenase, aconitase, isocitrate dehydrogenase, succinyl-CoA synthetase, succinate dehydrogenase, fumarase, malate dehydrogenase citrate synthase, isocitrate dehydrogenase, α-ketoglutarate dehydrogenase, succinate dehydrogenase, succinyl-CoA synthetase, fumarase, malate dehydrogenase citrate synthase, aconitase, isocitrate dehydrogenase, α-ketoglutarate dehydrogenase, succinyl-CoA synthetase, fumarase, malate dehydrogenase 90.The concentration (activity) of which of the listed enzymes is increased in the serum of patients with viral hepatitis? (1 βαθμός) acid phosphatase alanine aminotransferase (ALAT) lactate dehydrogenase creatine phosphokinase alpha-amylase Exam MCQ test in Biochemistry for students in Dental Medicine Dear students, Please, read carefully the following instructions. The test includes 90 MCQs, which are not mandatory. Each question has only one correct answer or only one correct combination (of 2 or 3 answers). You must mark the answers by clicking in the interactive field in front of the certain choice options. The points for each question indicate the number of the correct statements- 1, 2 or 3 points, respectively. Please, note that, if the time finishes, the test CANNOT BE SUBMITTED and EVALUATED by the system! The total time for completing the test is 90 minutes. You must have more than 60% of the total points in order to pass the Biochemistry final successfully. Good luck! Hi Соная, when you submit this form, the owner will be able to see your name and email address. 1. Which of the following statements about aminotransferases are TRUE? 1) they have NAD+ as a coenzyme 2) they have pyridoxal phosphate as a coenzyme 3) the serum ASAT concentration increases in myocardial infarction 4) the serum ASAT and ALAT concentrations decrease when a patient suffers from a liver disease (e.g. hepatitis) 5) they play an important role in the terminal detoxification of xenobiotics (2 Points) 3+4  1+5 2+3 1+4 2+5 2. Which of the following molecules is the product of the reaction, catalyzed by the pyruvate dehydrogenase complex? (1 Point) phosphoenolpyruvate acyl-CoA acetyl-CoA succinyl-CoA 1,3-bisphosphoglycerate 3. Which of the following processes are free oxidation processes? 1) heat production 2) beta-oxidation of fatty acids 3) oxidation of xenobiotics with cytochrome P450 4) hydroxylation of tryptophan to 5-hydroxytryptophan 5) oxidation of alpha-keto acids (3 Points) 1+2+3 1+4+5 1+3+4 3+4+5 2+3+4 4. Complex I of the mitochondrial respiratory chains: 1) receives electrons from the reduced cofactors of the oxidative processes in the mitochondrial matrix 2) gives electrons to complex II of the respiratory chain 3) transports electrons towards ubiquinone 4) works as a proton pump in the outer mitochondrial membrane 5) co-works with cytochromes as its cofactors (2 Points) 2+4 1+2 1+4 1+3 1+5 5. Which of the following statements about insulin and glucagon are TRUE? 1) insulin stimulates glucagon secretion 2) insulin is secreted in response to hyperglycemia 3) insulin is secreted in response to hypoglycemia 4) glucagon is an activator of gluconeogenesis and glycogen degradation in liver 5) insulin inhibits the pentose phosphate pathway (2 Points) 2+4 3+4 2+5 1+3 1+5 6. Which is the rate limiting step in the pentose phosphate pathway? (1 Point) transaldolase reaction hexokinase reaction ribose-5-phosphate isomerase reaction transketolase reaction glucose-6-phosphate dehydrogenase reaction  7. Which of the following phospholipids contain sphingosine, one fatty acid, a phosphate group and choline? (1 Point) glucocerebrosides phosphatidyl inositols ceramides sphingomyelins phosphatidylcholines 8. Porphyrias belong to a heterogenic group of diseases where: 1) the regulatory enzymes of heme synthesis “escape” their allosteric regulation 2) the reactions for detoxification of ammonia in the liver are impaired 3) there are deficiencies of enzymes included in heme synthesis pathway 4) there is a lack of heme and development of anemia 5) heme is overproduced (2 Points) 1+3 1+5 2+5 3+4  2+4 9. Heme synthesis occurs with high rate in: (1 Point) pancreas erythrocytes brain kidneys liver 10. Which of the following compounds derive from tryptophan? 1) NAD+ 2) melanin 3) dopamine 4) serotonin 5) triiodothyronine (T3) (2 Points) 2+4 3+4 1+4  2+5 1+5 11. Which properties are characteristic of the enzymes? 1) they have extremely high efficiency 2) they increase the activating energy of the reaction by formation of an enzyme-substrate complex 3) they have low substrate specificity 4) they act in large quantities 5) the activity and the synthesis of enzymes in the cells are regulated (2 Points) 2+5 3+4 2+4 1+5 1+3 12. Indicate the correct answers about the structure of elastin. 1) it forms a triple helix 2) it is synthesized as a soluble monomer (tropoelastin) and some proline residues are hydroxylated 3) it is a glycoprotein as there is glycosylation of some of the hydroxyproline residues 4) tropoelastin contains hydroxylated lysine residues (OH-Lys) 5) it does not contain regularly the Gly-X-Y sequences in its chain (2 Points) 1+5 3+4 2+4 2+5 1+3 13. Which of the following molecules DOES NOT serve as a precursor for gluconeogenesis? (1 Point) lactate acetoacetate methionine glycerol alanine 14. The oxidation-reduction processes are catalyzed by enzymes having as cofactors some of the following compounds. Which are those cofactors? 1) folic acid derivatives (tetrahydrofolate) 2) vitamin B2 derivatives (FMN and FAD) 3) vitamin B3 derivatives (NAD+ and NADP+) 4) vitamin B6 derivatives (pyridoxal phosphate) 5) vitamin B12 derivatives (cobalamin) (2 Points) 2+4 1+4 3+5 2+3 1+2 15. What type of bond connects the nucleotides in DNA? (1 Point) hydrogen 3', 5'-phosphodiester O-glycosidic N-glycosidic peptide 16. Which of the statements about the parathyroid hormone (PTH) are TRUE? 1) the low plasma Ca2+ level decreases PTH secretion 2) the low plasma Ca2+ level increases PTH secretion 3) it stimulates bone resorption and the release of Ca2+ in the extracellular space 4) binds to a serpentine receptor associated with G protein and activates the adenylyl cyclase pathway 5) inhibits the transcription of the enzyme 1-α-hydroxylase in the kidneys, necessary for the activation of vitamin D3 (3 Points) 2+3+4 1+3+5 2+4+5 1+3+4 3+4+5 17. The organic component of bone consists mainly of: (1 Point) osteocalcin hydroxyapatite calcium phosphate  type I collagen 18. Which of the listed organs possess GLUT2 (glucose transporter 2) ? 1) liver 2) brain 3) muscles 4) pancreatic beta-cells 5) adipose tissue (2 Points) 2+5 3+4 1+3 2+4 1+4 19. Which of the following reactions require S-adenosyl methionine (SAM) as a donor of methyl groups? 1) dopamine to norepinephrine 2) norepinephrine to epinephrine 3) ethanolamine to choline 4) dUMP to dTMP 5) synthesis of purines (2 Points)  2+5 2+3 3+4 1+3 1+5 20. In тхе red blood cells (RBCs): 1) glycolysis can be performed either in aerobic or anaerobic conditions 2) the end product of glycolysis is always lactate 3) RBCs contain smaller amounts of 2,3-bisphosphoglycerate compared to the rest of the cells 4) the pentose phosphate pathway is of crucial importance for RBCs 5) reduced glutathione is of great importance for RBCs (3 Points) 1+2+3 2+4+5 2+3+4 1+3+4 2+3+5 21. Indicate the CORRECT statements about digestion and the secretory activity of the stomach. 1) the secretion of hydrochloric acid by the parietal cells of gastric glands requires the enzyme carbonic anhydrase 2) the cells of gastric glands secrete digestive enzymes that break down the glycosidic bonds of starch 3) the “intrinsic factor” activates the formation of pepsin by pepsinogen 4) the chief cells of gastric glands synthesize and secrete pepsinogen 5) the chief cells of gastric glands synthesize and secrete pepsin (2 Points) 1+4 2+4 3+4 1+3 2+5 22. ni (1 Point) polyamines creatine phosphate nitric oxide (NO) ethanolamine  ornithine 23. Which of the following statements about the synthesis of TAG are CORRECT? 1) the synthesis occurs only in the adipose tissue 2) in the adipose tissue glycerol-3-phosphate is obtained from dihydroxyacetone phosphate from glycolysis 3) in the small intestine there is a monoacylglycerol pathway 4) the enzyme glycerol-3-phosphate acyltransferase is active in its phosphorylated form 5) the synthesis is inhibited by insulin (2 Points) 1+4 1+3 2+4 2+5 2+3 24. Which of the following statements are TRUE? 1) the higher Km is, the lower the affinity of an enzyme to the substrate is 2) the higher Km is, the higher the affinity of an enzyme to the substrate is 3) the lower Vmax is, the higher the stability of enzyme-substrate complex is 4) the higher Vmax is, the higher the stability of enzyme-substrate complex is  5) Km is that concentration of the substrate, at which the initial velocity of the reaction is half of the Vmax (Vmax/2) (3 Points) 1+3+5 2+3+4 2+3+5 2+4+5 1+4+5 25. Glutamate dehydrogenase: 1) catalyzes the oxidative deamination of glutamate to alpha-ketoglutarate using NAD+ as a cofactor 2) catalyzes the oxidative amination of glutamate using NAD+ as a cofactor 3) catalyzes the reductive amination of α-ketoglutarate to glutamate using NADPН as a cofactor 4) takes part in transdeamination (predeamination) 5) is allosterically activated by ATP and GTP (3 Points) 1+3+5 2+3+5 1+2+3 1+3+4  2+3+4 26. Which of the following mechanisms play role in ammonia detoxification? 1) glutamine biosynthesis in the brain 2) alanine biosynthesis in muscles 3) urea biosynthesis in muscles 4) urea biosynthesis in the kidneys 5) reductive amination of alpha-ketoglutarate (3 Points) 2+3+5 1+2+3 2+3+4 1+2+5 1+3+4 27. Which is the correct statement? (1 Point) unlike glycoproteins, proteoglycans contain carbohydrates in big proportion (up to 95%) the carbohydrate part of glycoproteins is called "glycosaminoglycan" all types of glycosaminoglycans contain building blocks that are highly sulfated  proteoglycans are low molecular weight polycationic substances proteoglycans have important biological functions in the blood 28. Which of the following statements regarding the oxidation of fatty acids are CORRECT? 1) β-oxidation of fatty acids with an even number of carbon atoms, below 18 occurs in the mitochondria of the cells 2) all end products of the oxidation of fatty acids with an odd number of carbon atoms is Acetyl-CoA 3) oxidation of short-chain fatty acids occurs in peroxisomes 4) very long-chain fatty acids are oxidized in the cytoplasm 5) FADH2 and NADH are obtained in each of the cycles of β-oxidation in the mitochondria (2 Points) 3+4 2+4 1+5 2+5 1+3 29. Which vitamins are needed as cofactors of the enzymes catalyzing the transformation of propionyl-CoA (one of the products of the oxidation of fatty acids with an odd number of carbon atoms)? 1) Vit. B9 2) Vit. PP (B3) 3) Vit. B6 4) Vit. B12 5) Vit. H (biotin) (2 Points) 2+4 1+3 1+5 3+4 4+5 30. Which processes do NOT take place in the liver? 1) synthesis of chylomicrons 2) urea synthesis 3) synthesis of direct bilirubin 4) synthesis of bile acids 5) ammoniagenesis (2 Points) 3+4 1+3 1+5  2+5 2+4 31. Which of the following statements about eicosanoids are TRUE? 1) they are synthesized in glands 2) they have a very long half-life 3) they are signal molecules and trigger signal pathways 4) they are synthesized in many tissues and work as local hormones 5) they are synthesized in small concentrations (3 Points) 2+3+5 1+3+5 1+2+3 3+4+5 2+3+4 32. Which of the following metabolites ARE NOT substrates or metabolites of the synthesis of cholesterol? 1) аcetyl-CoA 2) mevalonate 3) 3-hydroxy-3-methyl-glutaryl-CoA 4) malonyl-CoA  5) cholyl-CoA (2 Points) 3+4 4+5 1+5 2+4 1+3 33. Which of the following compounds are considered as “the key molecules” for the cell metabolism? 1) glyceraldehyde-3-phosphate 2) glucose-6-phosphate 3) acetyl-CoA 4) pyruvate 5) phosphoenolpyruvate (3 Points) 1+2+5 1+2+3 2+4+5 3+4+5 2+3+4  34. Indicate the correct statement about receptors located on the cell membrane. (1 Point) receptors with tyrosine kinase activity catalyze autophosphorylation and phosphorylation of other signaling molecules membrane receptors whose intracellular domains associate with G-proteins do not have an extracellular domains after activation, the receptor undergoes a process of "maturation" by cleavage of small peptides, which transmit the information to a downstream component of the signaling pathway after activation, the receptor is translocated to the nucleus, where it affects gene expression after activation, the receptor is transformed into a secondary messenger and transmits the information to a downstream component of the signaling pathway 35. Which of the following statements about ATP are TRUE? 1) ATP is a macroergic compound with two pyrophosphate bonds 2) ATP gives away its energy only by hydrolysis of its second pyrophosphate bond 3) ATP synthesis is coupled with endergonic processes 4) ATP synthesis is coupled with exergonic processes 5) ATP is a cofactor of the enzymes catalyzing kinase reactions (3 Points) 2+4+5 1+2+4  1+4+5 2+3+5 1+2+3 36. Which of the following processes occur during long-term starvation? 1) glycogenolysis 2) ketogenesis 3) lipolysis 4) glycogenogenesis 5) gluconeogenesis (3 Points) 2+3+4 1+2+3 1+2+5 2+3+5 1+3+4 37. Which of the following molecules is a high-energy (macroergic) phosphate derivative? (1 Point) glucose-6-phosphate  dihydroxyacetone phosphate fructose-6-phosphate 1,3-bisphosphoglycerate glycerol-3-phosphate 38. Which of the listed statements about calcitonin is WRONG? (1 Point) it is secreted when the Ca2+ level in blood is low the triggered signaling pathway in target cells is cAMP-dependent promotes renal excretion of Ca2+ it is secreted by the C-cells of the thyroid gland the receptors of calcitonin are G-protein associated membrane receptors 39. Which of the following redox-systems (redox pairs) belongs to the heme-containing compounds? (1 Point) NAD+/HADH oxidized Cytochrome c / reduced Cytochrome c ubiquinone/ubiquinol  FAD/FADH2 oxidized glutathione/reduced glutathione 40. Which is the end product of purine nucleotide catabolism in humans? (1 Point) creatinine urea uric acid xanthine ammonia 41. Which is the correct and complete sequence of the reactions in the Krebs cycle? (1 Point) citrate synthase, α-ketoglutarate dehydrogenase, aconitase, isocitrate dehydrogenase, succinyl-CoA synthetase, succinate dehydrogenase, fumarase, malate dehydrogenase citrate synthase, aconitase, isocitrate dehydrogenase, α-ketoglutarate dehydrogenase, succinyl-CoA synthetase, fumarase, malate dehydrogenase citrate synthase, isocitrate dehydrogenase, α-ketoglutarate dehydrogenase, succinate dehydrogenase, succinyl-CoA synthetase, fumarase, malate dehydrogenase citrate synthase, aconitase, isocitrate dehydrogenase, α-ketoglutarate dehydrogenase, succinyl-CoA synthetase, succinate dehydrogenase, fumarase, malate dehydrogenase  citrate synthase, aconitase, isocitrate dehydrogenase, α-ketoglutarate dehydrogenase, succinate dehydrogenase, succinyl-CoA synthetase, fumarase, malate dehydrogenase 42. Which of the following enzymes digests carbohydrates? (1 Point) pepsin lipase alpha-amylase phospholipase elastase 43. Which are the regulatory enzymes of pyrimidine biosynthesis? 1) ​carbamoyl phosphate synthetase II 2) ornithine transcarbamoylase 3) dihydroorotate dehydrogenase 4) ​aspartate transcarbamoylase 5) carbamoyl phosphate synthetase I (2 Points) 1+3 2+4 1+4  3+4 2+5 44. Which of the following statements regarding the synthesis and metabolism of lipoprotein complexes are TRUE? 1) pre-HDLs are synthesized only in the liver 2) VLDLs are metabolized by lipoprotein lipase 3) HDLs are produced as derivatives in VLDL metabolism 4) a high serum level of LDL increases the risk of myocardial infarction 5) HDLs carry cholesterol esters and clear up the excess of cholesterol from extrahepatic tissues (3 Points) 2+3+5 1+3+4 1+2+3 1+3+5 2+4+5 45. Gluconeogenesis occurs mainly in: 1) ​liver 2) brain 3) renal cortex 4) muscles 5) lungs (2 Points) 3+4 3+5 1+4 1+3 1+2 46. Which of the following statements about iron metabolism is TRUE? (1 Point) transferrin binds two ferrous (Fe2+) ions the major iron depot is the hemosiderin in the liver hephaestin and ceruloplasmin both reduce ferric (Fe3+) to ferrous (Fe2+) iron transferrin binds heme iron hepcidin decreases serum iron by blocking ferroportin (IREG1) 47. Which of the lipoprotein complexes transports exogenous (dietary) lipids, mainly TAG? (1 Point) VLDL  LDL chylomicrons HDL IDL 48. Please, indicate the CORRECT features of insulin signaling pathways. 1) insulin has a membrane receptor that does not have intrinsic tyrosine kinase activity and activates intracellular tyrosine kinases 2) insulin has a membrane receptor with intrinsic tyrosine kinase activity 3) insulin activates the phosphatidyl inositol-3-kinase (PI3K) pathway 4) a MAP kinase cascade is activated 5) JAK-STAT signaling pathway is activated (3 Points) 2+3+4 2+4+5 1+3+4 1+3+5 3+4+5 49. Which of the following statements about anaerobic glycolysis in humans are TRUE? 1) occurs only in the cytosol 2) occurs in both cytosol and mitochondria 3) the final product of glucose oxidation is ethanol 4) the final product of glucose oxidation is lactate 5) produces only 2 moles ATP per 1 mole glucose (3 Points) 2+3+4 2+3+5 1+4+5 1+3+4 1+3+5 50. Cholesterol: 1) is synthesized from Acetyl-CoA 2) is synthesized in the cytoplasm and the endoplasmic reticulum 3) the main regulatory enzyme of the synthesis is HMG-CoA synthase 4) is completely degraded in the liver 5) its synthesis is activated by insulin (3 Points) 1+2+5 1+2+3 1+3+4  2+3+4 2+3+5 51. Heme degradation is initiated by a substrate-inducible enzyme called: (1 Point) UDP-glucuronyl transferase protoporphyrinogen oxidase ferrochelatase heme oxygenase heme reductase 52. Indicate the protein involved in the storage of iron in cells? (1 Point) hepcidin ferritin ceruloplasmin divalent metal transporter 1 (DMT1) transferrin 53. Which of the following statements regarding vitamin K are CORRECT? 1) vitamin K is a water-soluble vitamin 2) vitamin K is required for prolyl and lysyl hydroxylation of collagen 3) vitamin K is required for prolyl hydroxylation of some of the blood clotting factors 4) vitamin K is required for gamma-glutamyl carboxylation of some of the blood clotting factors 5) deficiency of vitamin K results in bleeding (2 Points) 4+5 3+5 1+2 1+4 2+4 54. The absorption of vitamin B12 in the gastrointestinal tract (GIT) requires: (1 Point) phosphatidic acid transcobalamin II vitamin C transcobalamin I  intrinsic factor 55. Which of the listed properties are valid for serum albumin? 1) it transports bile acids 2) it transports free fatty acids 3) its synthesis increases in liver diseases 4) it does not participate in the maintenance of the osmotic pressure of the plasma 5) it transports mainly peptide hormones (2 Points) 1+2 1+3 2+5 3+4 2+4 56. Which of the following biologically active compounds DO NOT derive from tyrosine? 1) thyroxine 2) melanin 3) melatonin 4) GABA 5) epinephrine (2 Points) 2+5 3+4 2+4 1+5 1+3 57. “Jaundice” is a condition of hyperbilirubinemia, the reasons for which could be: 1) intensive degradation of N-containing substrates in the cells 2) increased intake of N-containing molecules with food 3) abnormal breakdown of red blood cells (accelerated hemolysis) 4) obstruction of the biliary paths 5) defects in the enzyme UDP-glucuronyl transferase liver or other liver diseases (3 Points) 2+3+4 2+4+5 3+4+5 1+3+4 1+3+5 58.  Which of the following statements about glycogen degradation in the liver is TRUE? (1 Point) it is a source of energy for the liver cells it is the mechanism for maintenance of the blood glucose level during long-term starvation the regulatory enzyme is alpha-glucosidase it is the first mechanism for maintenance of the blood glucose level during fasting periods the regulatory enzyme is the debranching enzyme 59. The pentose phosphate pathway is: 1) localized in the mitochondria 2) localized in the cytosol 3) a source of NADPH for fatty acids biosynthesis 4) a source of NADPH for the respiratory chain 5) an alternative catabolic pathway for the degradation of glucose in muscles (2 Points) 1+3 2+3 2+4 3+5  1+5 60. Vitamin D3: 1) is a cholesterol derivative 2) its active form is 1,25-dihydroxycholecalciferol (calcitriol) 3) is synthesized in the small intestine 4) its synthesis is activated by calcitonin 5) it inhibits the absorption of calcium in the small intestine (2 Points) 2+4 1+2 2+5 1+4 3+4 61. How many ATP molecules are synthesized in the microsomal electron-transport chains? (1 Point) three ATP molecules one ATP molecule no ATP molecules  two ATP molecules twelve ATP molecules 62. Which of the following statements about the „de novo” synthesis of purines are TRUE? 1) the purine ring is built by adding atoms onto the basis of PRPP 2) phosphoribosyl is added to the already formed purine ring 3) a common metabolite of AMP and GMP synthesis is IMP 4) the synthesis begins with carbamoyl phosphate and aspartate 5) glycine and glutamine are involved in the synthesis (3 Points) 1+3+4 2+3+4 1+4+5 2+3+5 1+3+5 63. Which of the following reactions from the urea cycle demand ATP? 1) arginine -> ornithine + urea 2) ornithine + carbamoyl phosphate -> citrulline 3) NH3 + CO2 -> carbamoyl phosphate 4) citrulline + aspartate -> argininosuccinate  5) argininosuccinate -> arginine + fumarate (2 Points) 2+4 1+5 3+4 2+5 1+3 64. Galactose is: 1) metabolized mainly in the liver 2) metabolized mainly in the muscles 3) metabolized mainly in the small intestine 4) activated by phosphorylation mainly by galactokinase 5) activated by phosphorylation mainly by hexokinase (2 Points) 1+4 1+3 1+5 3+4 2+4  65. The glycerol produced in lipolysis in adipose tissue: 1) is activated by glycerol kinase in the adipose tissue 2) is released into the bloodstream and then enters the muscles 3) is converted to glycerol-3-phosphate in the liver 4) is converted to glyceraldehyde-3-phosphate in the liver 5) is used for gluconeogenesis in the liver (2 Points) 1+3 2+4 2+5 1+4 3+5 66. Which of the following enzymes release arachidonic acid from the membrane glycerophospholipids? (1 Point) phospholipase A2 phospholipase C phospholipase D phospholipase A1  all phospholipases 67. Which statements concerning the anabolic processes are CORRECT? 1) they are processes of synthesis of cell-specific proteins and nucleic acids 2) they are processes of energy accumulation in microergic compounds 3) they are processes of oxidation of substrate molecules 4) they are processes of synthesis of ATP 5) they are reductive processes that “store” energy in the bonds of organic molecules (2 Points) 1+5 2+3 3+5 1+4 2+4 68. Which of the following shuttles is used in the synthesis of fatty acids? (1 Point) carnitine shuttle shuttle of gluconeogenesis citrate shuttle  malate shuttle glycerol-3-phosphate shuttle 69. Which vitamin is involved in the structure of Coenzyme A? (1 Point) vitamin B1 (thiamine) vitamin B12 (cobalamin) vitamin B3 (nicotinamide) vitamin B2 (riboflavin) vitamin B5 (pantothenic acid) 70. Which of the listed statements about osteoblasts are CORRECT? 1) their activation leads to bone resorption 2) their activation leads to bone formation 3) they activate osteoclasts 4) they suppress osteoclasts 5) they express RANK (the receptor activator of NF-kB) (2 Points) 2+5 1+3  2+4 2+3 1+4 71. The synthesis of conjugated bile acids requires: 1) 7-α-hydroxylase 2) 25-hydroxylase 3) NADPH 4) glycine and taurine 5) citrate and malate (3 Points) 1+3+5 2+3+5 2+3+4 1+2+3 1+3+4 72. Which of the following statements about hormones are TRUE? 1) hydrophobic hormones are transported across cell membranes and are recognized and bound by intracellular receptors 2) hydrophilic hormones do not enter the cells and are recognized and bound by cell membrane receptors 3) hydrophilic hormones are transported across the cell membrane and are recognized and bound by intracellular receptors 4) hydrophobic hormones do not enter cells and are recognized and bound by receptors on the cell membrane 5) are effective only at very high concentrations (2 Points) 3+4 2+5 1+2 2+4 1+5 73. Which of the following statements about the regulation of the synthesis of fatty acids is TRUE? (1 Point) the main regulatory enzyme is the acyl synthase complex the synthesis is inhibited by insulin citrate activates the main regulatory enzyme the main regulatory enzyme is active in its phosphorylated form the end product is an allosteric activator 74. Which of the following statements about folic acid are TRUE? 1) its cofactor form is tetrahydrofolate 2) its cofactor form is dihydrofolate 3) it binds and carries C1-unit for synthesis of creatine phosphate 4) it binds and carries C1-units for the "de novo" synthesis of the purine ring 5) its deficiency causes hemolytic anaemia (2 Points) 1+4 3+5 2+5 1+3 2+4 75. The irreversible kinase reactions in glycolysis are catalyzed by: 1) hexokinase (glucokinase) 2) phosphoglycerate kinase 3) phosphofructokinase 4) phosphoenolpyruvate carboxykinase 5) pyruvate kinase (3 Points) 1+3+4 2+3+4  2+3+5 1+3+5 1+2+3 76. The mitochondrial electron-transport chains: 1) exist as multienzyme complexes that create electro-chemical gradient, whose energy is used in ATP synthesis 2) are controlled by the ratio ubiquinone/ubiquinone.H2 3) consist of five (5) multienzyme complexes + an ATP-ase 4) are located in the inner mitochondrial membrane 5) require constant oxygen supply (3 Points) 1+2+3 2+3+4 3+4+5 1+3+4 1+4+5 77. Which of the following statements are CORRECT? 1) fibrous proteins have polypeptide chains arranged in long strands 2) globular proteins have polypeptide chains folded into a spherical shape 3) most enzymes and regulatory proteins are fibrous 4) globular proteins are insoluble in water 5) fibrous proteins are keratin, collagen and elastin (3 Points) 2+3+5 1+2+3 1+2+5 1+3+4 2+3+4 78. Which of the following hormones have a membrane receptor? 1) retinoic acid 2) ACTH 3) triiodothyronine 4) glucagon 5) calcitriol (2 Points) 2+5 3+4 1+5 2+4  1+3 79. Which of the following statements about Krebs cycle is TRUE? 1) the regulatory enzymes are more active when the levels of ATP are high 2) the regulatory enzymes are less active when the levels of NADH are high 3) the cycle represents the final steps of oxidation of C-atoms that come from different substrates of biological oxidation 4) some of the intermediates of the cycle could be used for the synthesis of carbohydrates, lipids and proteins 5) the enzyme activities of the cycle are also found in the cytoplasm and various cell organelles (3 Points) 1+2+3 2+3+5 1+3+4 1+3+5 2+3+4 80. Aldolase B is an enzyme in the catabolic pathway of: (1 Point) glucose purine bases  triacylglycerols fructose galactose 81. The concentration (activity) of which of the listed enzymes is increased in the serum of patients with viral hepatitis? (1 Point) alpha-amylase lactate dehydrogenase creatine phosphokinase acid phosphatase alanine aminotransferase (ALAT) 82. Which of the following statements about phenylalanine degradation are TRUE? 1) phenylalanine hydroxylase uses ascorbic acid as a cofactor 2) phenylalanine hydroxylase uses tetrahydrobiopterin as a cofactor 3) phenylalanine hydroxylase uses NADPH as a cofactor 4) a deficiency of homogentisate oxidase causes tyrosinemia type II 5) a deficiency of phenylalanine hydroxylase results in higher concentration of phenylpyruvate, phenyllactate and phenylacetate (2 Points)  2+5 2+4 1+4 1+5 3+4 83. Acetyl-CoA is NOT a metabolite of: (1 Point) ketogenesis citric acid cycle glycolysis β-oxidation synthesis of cholesterol 84. Glycogen synthase is: (1 Point) active in its dephosphorylated form activated by adrenalin inactivated by insulin  activated by glucagon inactive in its dephosphorylated form 85. Ketolysis occurs in: (1 Point) the cytoplasm of hepatocytes the cytoplasm of extrahepatic tissues the mitochondria of extrahepatic tissues the endoplasmic reticulum of neurons the mitochondria of hepatocytes 86. Ketogenesis is active during: 1) starvation 2) well-fed state 3) diabetes mellitus type I 4) normal insulin secretion 5) inhibited β-oxidation (2 Points) 1+5 1+3  2+4 2+5 3+4 87. Which of the statements concerning covalent modification of enzymes by phosphorylation /dephosphorylation are WRONG? 1) reversible phosphorylation/dephosphorylation is one of the ways to regulate enzyme activity 2) dephosphorylation is catalyzed by enzymes called serine/threonine protein kinases 3) phosphorylation is catalyzed by enzymes called protein phosphatases 4) the regulation by phosphorylation/dephosphorylation is under nervous and hormonal control 5) regulation is achieved by causing a slight conformational change affecting the active site of the enzyme (2 Points) 1+3 3+4 2+3 1+5 2+5 88. Which of the following statements about the biochemical characteristics of blood clotting are TRUE? 1) zymogens of serine proteases are involved 2) the extrinsic and the intrinsic pathway of blood clotting are not linked 3) transglutaminase (factor XIII) destroys fibrin molecules 4) several of the blood clotting factors undergo maturation via Vitamin K-dependent carboxylation 5) thrombin is a tyrosine protein kinase (2 Points) 2+4 1+3 1+4 3+4 2+5 89. Which is the main product of the digestion of the triacylglycerols (TAG) in the small intestine? (1 Point) 2-monoacylglycerol DAG glycerol-3-phosphate phosphatidic acid  lysolecithin 90. The N-atom in carbamoyl phosphate, used for the pyrimidine ring synthesis, derives from: (1 Point) ammonia (NH3) glycine glutamate aspartate glutamine Submit This content is created by the owner of the form. The data you submit will be sent to the form owner. Never give out your password. Powered by Microsoft Forms | ​Privacy and cookies​ | ​Terms of use Biochemistry Final 2019-2020 – Medicine 1. Which of the following statements regarding the biosynthesis of fatty acids are CORRECT? 1. the acyl synthase complex is a dimer and each monomer contains seven enzymatic activities and an acyl carrier protein 2) NADPH is needed for the synthesis of fatty acids 3) this anabolic pathway is located in the mitochondria 4) acetyl-CoA carboxylase is inhibited by phosphorylation stimulated by glucagon 5) acetyl-CoA carboxylase is inhibited by dephosphorylation stumulated by insulin (3 Points) o 1+2+4 o 1+3+5 o 2+3+5 o 2+3+4 o 1+2+5 2.Which of the following chemical bonds/interactions are involved in the formation of the tertiary structure of proteins? 1) ionic, dipole and ion-dipole interactions between amino acid radicals 2) hydrophobic interactions between amino acid radicals 3) peptide bonds 4) hydrogen bonds between amino acid radicals 5) hydrogen bonds between neighboring peptide groups (3 Points) o 2+3+5 o 1+2+5 o 1+2+3 o 2+3+4 o 1+2+4 3. Which of the following statements about nucleotide synthesis are TRUE? 1) the pyrimidine ring is formed by adding atoms to PRPP 2) the purine ring is formed by adding atoms to PRPP 3) the synthesis of dТМP requires tetrahydrofolate derivatives 4) the synthesis of dТМP requires S-adenosylmethionine (S-AM) 5) the formation of the purine ring requires tetrahydrofolate derivatives (3 Points) o 1+3+5 o 2+3+5 o 2+4+5 o 1+4+5 o 3+4+5 4. How is the acetyl radical of acetyl-CoA transferred from the mitochondria into the cytoplasm in order to be used for the synthesis of fatty acids? (1 Point) o in the form of acetoacetate o in the form of citrate o via the malate shuttle o via the glycerol phosphate shuttle o via the carnitine shuttle 5. Which enzymes catalyze reactions of oxidative phosphorylation at substrate level? 1) glucose-6-phosphate dehydrogenase and lactonase 2) fumarase and malate dehydrogenase 3) glyceraldehyde-3-phosphate dehydrogenase and phosphoglycerate kinase 4) 1,3-bisphosphoglycerate mutase and lactate dehydrogenase 5) enolase and pyruvate kinase (2 Points)  o 2+3 o 3+5 o 4+5 o 1+3 o 3+4 6. Which of the following statements about the redox potential are TRUE? 1) it provides information about the affinity of the redox system to electrons 2) it depends on the concentrations of the oxidized and reduced forms of the redox system 3) the flow of electrons runs from redox systems with higher redox potential to those with lower redox potential 4) the flow of electrons runs from redox systems with lower redox potential to those with higher redox potential 5) the redox couple NAD+/ NADH has a redox potential close to this of cytochromes (3 Points) o 1+4+5 o 1+2+3 o 2+3+5 o 1+3+6 o 1+2+4 7. Choose the correct statements about calcium and phosphate homeostasis: 1) secretion of the parathyroid hormone is stimulated at low calcium serum level 2) 1,25-dihydroxycalciferol stimulates calcium and phosphate excretion 3) deficiency of 1,25-dihydroxycalciferol in children and adults is called osteomalacia 4) parathyroid hormone stimulates the synthesis of 1,25- dihydroxycalciferol  5) the main effect of calcitonin is the activation of bone resorption by osteoclasts (2 Points) o 1+4 o 3+5 o 2+4 o 2+5 o 1+3 8. Which of the following statements about fructose metabolism are TRUE? 1) fructose is a major source of energy in spermatozoa 2) fructose oxidation is an insulin dependent pathway 3) fructose oxidation is an insulin independent pathway 4) fructose is transported through the cell plasma membrane via GLUT 5 5) fructose is transported through the cell plasma membrane via GLUT 4 (3 Points) o 1+3+4 o 2+4+5 o 1+3+5 o 1+2+5 o 1+2+4 9. Which of the keto acids participate both in the citric acid cycle and in transamination? 1) alanine 2) oxaloacetate 3) acetoacetate 4) α- ketoglutarate 5) pyruvate (2 Points)  o 3+5 o 2+3 o 1+3 o 2+4 o 1+4 10. Which of the following reactions require S-adenosylmethionine as a donor of a methyl group? 1) the conversion of noradrenaline to adrenaline 2) the conversion of phenylalanine to tyrosine 3) the conversion of ethanolamine to choline 4) the conversion of guanidinoacetate to creatine 5) the conversion of glutamate to glutamine (3 Points) o 1+2+5 o 1+3+4 o 2+4+5 o 2+3+5 o 1+2+4 11. Which of the following hormones has a membrane receptor? 1) retinoic acid 2) ACTH 3) iodothyronine 4) glucagon 5) calcitriol (2 Points) o 1+3 o 3+5 o 1+5 o 2+4 o 2+5 12.Which of the listed statements regarding the oxidation of fatty acids with an odd number of C-atoms are CORRECT? 1) the oxidation of fatty acids is a mitochondrial process 2) the oxidation of fatty acids is a cytosolic process 3) propionyl-CoA is obtained, which can be converted to glucose in gluconeogenesis 4) malonyl-CoA is obtained, which is then converted to succinyl-CoA 5) it requires biotin and vitamin B12 (3 Points) o 1+3+5 o 2+4+5 o 1+4+5 o 3+4+5 o 2+3+5 13. Which is the major regulatory enzyme of gluconeogenesis? (1 Point) o glucose 6-phosphate dehydrogenase o fructose 2,6-bisphosphatase o phosphoenolpyruvate carboxykinase o glucose 6-phosphatase o fructose 1,6-bisphosphatase 14. How is ammonia neutralized in the extrahepatic tissues? 1) through oxidative deamination 2) through reductive amination of α- ketoglutarate 3) through urea synthesis 4) through glutaminolysis 5) through glutamine synthesis (2 Points) o 3+5 o 1+3  o 2+3 o 2+5 o 1+4 15. Which are the CORRECT statements about cholesterol synthesis? 1) the regulatory enzyme is 3-Hydroxy-3-Methylglutaryl-CoA synthase 2) the regulatory enzyme is 3-Hydroxy-3-Methylglutaryl-CoA reductase 3) it occurs in the mitochondria and the peroxisomes 4) it occurs in the cytosol and the endoplasmic reticulum 5) requires NADPH (3 Points) o 1+4+5 o 2+3+5 o 3+4+5 o 1+3+5 o 2+4+5 16. Which of the following enzymes take part in glycogen synthesis from glucose in the liver? 1) hexokinase 2) glucokinase 3) phosphoglucomutase 4) phosphohexose isomerase - not sure 5) glycogen synthase (3 Points) o 1+4+5 o 1+3+5 o 3+4+5 o 2+3+5 o 2+4+5 17. Which are the CORRECT statements? 1) chylomicrons are formed in the liver 2) chylomicrons are formed in the small intestine 3) LDLs are formed in the liver 4) VLDLs are formed in the liver 5) the main integral apolipoprotein of VLDL is apo B-100 (3 Points) o 1+4+5 o 2+3+5 o 2+4+5 o 1+3+5 o 3+4+5 18. Which are the CORRECT statements regarding the compounds, called ketone bodies? 1) they are synthesized in a state of an excess of carbohydrates 2) they are only synthesized in the mitochondria of hepatocytes 3) they are only synthesized in the mitochondria of muscle cells 4) they are a source of energy for the liver 5) they are degraded in the brain and muscles in a state of carbohydrate deficiency (2 Points) o 3+5 o 2+5 o 1+4 o 1+3 o 2+4 19. Which of the following enzymes of the citric acid cycle are regulatory? 1) citrate synthase 2) isocitrate dehydrogenase  3) fumarase 4) α-ketoglutarate dehydrogenase 5) succinate dehydrogenase (3 Points) o 2+4+5 o 1+2+4 o 2+3+4 o 1+2+5 o 1+3+5 20. Which of the following statements about the hormone hepcidin are TRUE? 1) it increases the serum iron concentration 2) it decreases the serum iron concentration 3) it does not participate in the regulation of iron homeostasis 4) it binds to the iron transport protein transferrin 5) it binds and blocks the iron exporter ferroportin (2 Points) o 1+4 o 2+5 o 3+5 o 2+4 o 1+5 21. Which of the following statements about nucleosides are TRUE? double check please 1) they are constructed of a nitrogen base and a pentose 2) in the structure of nucleic acids, nucleosides are connected by 3’-5’-phosphodiester bonds 3) the N-glycosidic bond between the base and the pentose in purine nucleosides includes atom N1 4) the N-glycosidic bond between the base and the pentose in pyrimidine nucleosides includes atom N1  5) predominate is syn conformation (2 Points) o 1+3 o 2+4 o 2+5 o 3+5 o 1+4 22. Indicate the CORRECT statements about jaundice. 1) in case of obstructive jaundice, urobilinogen is detected in the urine 2) in case of obstructive jaundice, urobilinogen is absent in the urine 3) parenchymal jaundice is caused by an obstruction of the bile ducts 4) in case of hemolytic anemia, the indirect bilirubin in the serum is increased 5) in case of hemolytic anemia the direct bilirubin in the serum is increased (2 Points) o 3+5 o 1+4 o 2+5 o 2+4 o 1+3 23. Carboxylation of pyruvate to oxaloacetate: 1) requires vitamin B6 as a prosthetic group of the enzyme 2) requires vitamin H as a prosthetic group of the enzyme 3) requires GTP as an energy donor 4) requires ATP as a source of energy 5) occurs in the mitochondria (3 Points)  o 1+4+5 o 1+3+5 o 2+3+5 o 1+2+5 o 2+4+5 24. Tyrosinemias are genetically determined deficiencies of enzymes from the catabolic chain of: (1 Point) o phenylalanine o tryptophan o histidine o valine o leucine 25. Which of the following histone proteins are involved in the formation of the nucleosome? 1) H1 2) H2A 3) H2B 4) H2C 5) H3 (3 Points) o 1+2+4 o 2+3+5 o 1+4+5 o 2+3+4 o 3+4+5 26. Which of the following statements about heme synthesis are TRUE? 1) the main regulatory enzyme is δ-aminolevulinate (ALA) dehydratase 2) the main regulatory enzyme is δ-aminolevulinate (ALA) synthase 3) the heme is the major allosteric activator of the main regulatory enzyme 4) the initial substrates for heme synthesis are succinyl-CoA and glycine 5) porphyria could be caused by a deficiency of ALA synthase (2 Points) o 4+5 o 1+4 o 2+4 o 2+3 o 1+5 27. Which of the following prostanoids is the strongest antiagregant, produced by the endothelium? (1 Point) o PGG2 o PGI2 o PGD2 o PGH2 o PGE2 28. Sphingolipidoses are diseases caused by enzyme deficiencies in the: 1) synthesis of sphingomyelins 2) catabolism of sphingomyelins 3) synthesis of gangliosides 4) catabolism of gangliosides 5) catabolism of cerebrosides (3 Points) o 2+4+5 o 1+3+5 o 1+4+5 o 1+2+3 o 2+3+4 29. Choose the correct statements about erythrocytes: 1) 2,3-bisphosphoglycerate decreases the affinity of hemoglobin to oxygen 2) fructose-2,6-bisphosphate is the main allosteric regulator of the affinity of hemoglobin for oxygen 3) methemoglobin reductase is an important enzyme in erythrocytes, which restores functionally active hemoglobin 4) NADPH-oxidase is an important antioxidant enzyme in erythrocytes 5) deficiency of vitamin B12 and folic acid leads to microcytic hypochromic anemia (2 Points) o 2+3 o 1+5 o 1+3 o 4+5 o 2+4 30. Choose the CORRECT statements about the hormones of the hypothalamic-pituitary-gonadal axis: 1) gonadotropin-releasing hormone (GnRH) acts through a plasma membrane receptor, whose stimulation leads to the activation of guanylyl cyclase 2) follicle-stimulating hormone (FSH) and luteinizing hormone (LH) are steroid hormones with lipophilic structure 3) testosterone and estradiol regulate the secretion of FSH and LH from the pituitary gland and GnRH from the hypothalamus on the principle of a negative feedback inhibition 4) enzymes involved in the synthesis of estrogens (female sex hormones) are the aromatases 5) dehydroepiandrosterone (DHEA) is produced by adrenal glands (3 Points) o 3+4+5 o 1+2+3 o 1+3+5  o 1+2+4 o 2+4+5 31. Sphingomyelin is produced after an interaction of ceramide with: (1 Point) o serine o CDP-choline o galactose o glucose o inositol 32. Which of the following statements describe the role of glucagon during the state of starvation. 1) it stimulates lipolysis in the adipose tissue by activating cAMP- dependent protein kinase, which activates the hormone-sensitive lipase 2) it stimulates the phosphorylation and inactivation of acetyl-CoA carboxylase, inhibiting the synthesis of fatty acids 3) it stimulates the synthesis of glycogen in the liver 4) it stimulates glycogenolysis and gluconeogenesis in the liver 5) it stimulates the synthesis of fructose-2,6-bisphosphate - the major activator of gluconeogenesis (3 Points) o 1+ 4 + 5 o 1+3+5 o 2+4+5 o 1+2+3 o 1+2+4 33. How many ATP molecules are synthesized by the enzymes of the citric acid cycle and respiratory chains for one molecule of acetyl-CoA which is oxidized? (1 Point) o 12 o 38 - pretty sure o 11 o 1 o 36 34. NF-κB: 1) is a transcription factor 2) is an enzyme 3) stimulats the expression of several pro-inflammatory genes 4) is a heterotrimeric complex 5) is inhibited by glucocorticoids (3 Points) o 1+4+5 o 2+3+5 o 2+4+5 o 1+2+4 o 1+3+5 35. Natriuretic peptides (NUP): 1) increase the rate of glomerular filtration in the kidneys, which leads to increased excretion of sodium ions and water 2) reduce the rate of glomerular filtration in the kidneys, leading to reabsorption of sodium ions and water 3) increase renin release, thereby increasing angiotensin II and aldosterone levels 4) reduce renin release, thereby reducing angiotensin II and aldosterone levels 5) when they bind to a receptor, the enzyme guanylyl cyclase is activated, which leads to the formation of cGMP  (3 Points) o 1+4+5 o 2+4+5 o 2+3+5 o 1+2+5 o 1+3+5 36. Choose the CORRECT statements about the phosphoinositide system: 1) it activates protein kinase B (PKB) 2) it activates protein kinase C (PKC) 3) the secondary messengers inositol-1,4,5-triphosphate (IP3) and diacylglycerol (DAG) are formed 4) the secondary messengers phosphatidylinositol-3,4,5- triphosphate and diacylglycerol are formed 5) receptors, having a tyrosine kinase activity, are part of this signaling pathway (2 Points) o 2+5 o 4+5 o 1+3 o 1+4 o 2+3 37. Which of the following enzymes are involved in the breakdown of heme and the metabolism of bile pigments? 1) heme oxygenase 2) heme synthase 3) biliverdin reductase 4) bilirubin UDP-glucuronyl transferase 5) δ-aminolevulinate synthase (3 Points) o 1+3+5  o 2+3+4 o 2+4+5 o 1+3+4 o 3+4+5 38. Why does the adenylyl system (ADP/ATP) play a central role in bioenergetic processes? 1) during the hydrolysis of ATP the highest amount of energy is released compared to the other macroergic compounds 2) ATP has an intermediate value of free energy between high and low energy compounds 3) ATP can give a part of its energy and a phosphate group to normoergic compounds, which activates them 4) ADP can receive a part of the energy and a phosphate group of high energy compounds 5) it could transform different types of energy into macroergic bonds and/or heat (3 Points) o 1+2+5 o 3+4+5 o 2+3+4 o 2+4+5 o 1+3+4 39. Which of the following statements about iron metabolism are WRONG? 1) physiologically iron is deposited in the form of hemosiderin 2) physiologically iron is deposited in the form of ferritin 3) transferrin can bind only ferrous (Fe2+) cations 4) transferrin can bind only ferric (Fe3+) cations 5) there is no physiological mechanism for the excretion of iron from the body (2 Points) o 2+4 o 3+5  o 1+4 o 1+3 o 2+5 40. The primary structure of proteins: 1) is the level of organization, due to steric interactions between distant amino acid residues 2) is the number, type and sequence of amino acids in the polypeptide chain 3) determines the conformation of proteins and the following functional specificity 4) is genetically determined 5) is not genetically determined (3 Points) o 1+3+4 o 1+2+4 o 1+2+5 o 2+3+4 o 2+3+5 41. Which nucleotide is the intracellular secondary messenger used by adrenaline in the muscles and by glucagon in the liver? (1 Point) o cyclic 3',5'-AMP o AMP o ATPf o ADP o cyclic 3',5'-GMP 42. Which of the following statements about the pyruvate dehydrogenase (PDH) multienzyme complex are TRUE? 1) it catalyzes the link reaction between glycolysis and the Krebs cycle 2) it is activated by the high level of NADH 3) has five different enzymatic activities and requires three different cofactors1 4) its enzyme activity is controlled by the levels of substrates and reaction products (NAD +/NADH, ATP/ADP) 5) its enzyme activity is controlled by the ratio insulin/glucagon (through phosphorylation/dephosphorylation of the enzyme) (3 Points) o 2+4+5 o 2+3+4 o 1+3+5 o 1+4+5 o 1+3+4 43. Factors, favoring the development of atherosclerosis can be: 1) smoking 2) high blood pressure 3) hypercholesterolemia 4) formation of cholesteryl esters in HDL 5) excess consumption of phospholipids (3 Points) o 2+4+5 o 3+4+5 o 2+3+4 o 1+3+5 o 1+2+3 44. Which are the CORRECT statements about steroid hormones? 1) corticosteroid hormones are cholesterol derivatives 2) corticosteroid hormones are synthesized in the adrenal cortex 3) aldosterone is synthesized in zona fasciculatа 4) cortisol is a mineralocorticoid 5) pregnenolone is an intermediate metabolite in steroid hormone synthesis (3 Points) o 2+4+5 o 2+3+5 o 1+2+4 o 1+3+5 o 1+2+5 45. Which isoenzyme of creatine kinase has a diagnostic role for detection of myocardial infarction? (1 Point) o ВВ o HM o HH o МВ o ММ 46. Choose the CORRECT answers, describing the molecular features of the MAPK signaling pathway: 1) the pathway requires a change in Ca2+ levels to be activated 2) the pathway requires a change in cAMP levels to be activated 3) the pathway is a three-step cascade of activation of serine/threonine protein kinases that transfer information to transcription factors 4) the activated enzymes in this pathway belong to the group of serine proteases  5) the activation of some of the protein kinases from the pathway requires activation of a protein from the small G-protein family (Ras) (2 Points) o 1+3 o 3+5 o 1+4 o 2+3 o 2+4 47. Which of the following statements are CORRECT? 1) leptin is a small protein, synthesized in the hypothalamus 2) leptin is synthesized in the adipose tissue and binds to specific receptors in the hypothalamus 3) leptin inhibits the appetite and increases the consumption of energy in the organism 4) leptin inhibits heat production 5) fasting stimulates the release of leptin (2 Points) o 3+4 o 2+3 o 1+5 o 1+3 o 2+4 48. Which of the following regulatory mechanisms are used to regulate the enzyme activity of the pyruvate dehydrogenase complex (PDH)? 1) its activity is decreased by elevated levels of the products of the reaction via allosteric control 2) its activity can be modulated only through reversible covalent modification (phosphorylation/dephosphorylation) 3) insulin causes the complex to be phosphorylated, thus increases its activity  4) the complex is more active when dephosphorylated, a process triggered by insulin 5) the protein kinase that phosphorylates the PDH complex is sensitive to changes in the levels of ATP (3 Points) o 2+3+5 o 1+2+3 o 1+3+5 o 2+4+5 o 1+4+5 49. Which is the end product of purine catabolism in humans? (1 Point) o β-aminoisobutyrate o uric acid o orotate o xanthine o bilirubin 50. Which of the amino acids are glycogenic and non-essential? 1) cysteine 2) glutamate 3) phenylalanine 4) leucine 5) methionine (2 Points) o 2+5 o 3+4 o 2+4 o 2+3 o 1+2 51. Which of the following molecules could act as uncoupling agents? 1) fatty acids 2) ubiquinone (CoQ) 3) bilirubin 4) triiodothyronine/thyroxine 5) glucose (3 Points) o 1+2+3 o 2+3+4 o 1+4+5 o 1+3+4 o 2+3+5 52. Which of the listed statements regarding the urea cycle are TRUE? 1) it takes place in the mitochondria and the cytoplasm 2) it takes place in the endoplasmic reticulum and the cytoplasm 3) it takes place in the liver 4) it takes place in the liver and the small intestine 5) the regulatory enzyme is ornithine transcarbamoylase (2 Points) o 2+3 o 1+3 o 2+4 o 3+5 o 1+4 53. Positive acute phase proteins include: 1) C-reactive protein 2) serum amyloid A 3) fibrinogen 4) albumin 5) defensins (3 Points) o 2+3+4 o 2+3+5 o 3+4+5 o 1+4+5 o 1+2+3 54. Which metabolites are intermediates in the biosynthesis of cholesterol? 1) mevalonate 2) lanosterol 3) squalene 4) sorbitol 5) glycerol (3 Points) o 3+4+5 o 2+3+4 o 1+3+5 o 2+4+5 o 1+2+3 55. Which statements about isoenzymes are TRUE? 1) they are different, biologically active forms of the same enzyme 2) they are the inactive forms of a biologically active enzyme 3) they catalyze different reactions 4) they catalyze the same reactions 5) they have different tissue localization (3 Points) o 1+2+4 o 2+4+5 o 1+3+5 o 1+4+5 o 2+3+5 56. Which is the cofactor of the enzyme glucose-6-phosphate dehydrogenase? (1 Point) o FAD o NADH o NADP+ o NAD+ o NADPH 57. The major plasma protein responsible for the regulation of the osmotic pressure of blood is: (1 Point) o α-macroglobulin o C-reactive protein o hemoglobin o haptoglobin o albumin 58. Which of the following are obtained from arginine? 1) dopamine 2) creatine phosphate 3) nitric oxide 4) polyamines 5) serotonin (3 Points) o 2+3+4 o 3+4+5 o 1+3+5 o 2+3+5 o 1+4+5 59. Which of the complexes of the respiratory chains work as proton pumps, making the electrochemical gradient? (1 Point) o complexes II, III, and IV o complexes II, III, IV and cytochrome c o all complexes of the respiratory chains o complexes I, II and III o complexes I, III, and IV 60. Which of the following is equal to the Michaelis constant (Km)? (1 Point) o k -1 + k +1 o k -1 / k +1 o k +1 + k +2 / k -1 o k +1 / k -1 o k -1 + k +2 / k +1 61. Which of the following features concern triacylglycerols? 1) amphipathic (both hydrophobic and hydrophylic) molecules 2) hydrophobic molecules 3) are transported by lipoproteins 4) are a storage form of energy in the adipose tissue 5) are hydrolyzed by phospholipase (3 Points) o 1+3+5 o 2+3+5 o 2+3+4 o 3+4+5 o 1+4+5 62. Which disease is caused by a genetic defect of an enzyme in the catabolism of valine, isoleucine and methionine? (1 Point) o albinism o pellagra o Lesch-Nyhan syndrome o alkaptonuria o methylmalonylemia 63. How many ATP molecules are synthesized when one glucose molecule is completely oxidized to carbon dioxide and water? (1 Point) o 12 or 14, depending on the shuttle mechanisms that transport electrons from cytoplasmic NADH to the respiratory chains o 2 or 4, depending on the shuttle mechanisms that transport electrons from cytoplasmic NADH to the respiratory chains o 4 or 6, depending on the shuttle mechanisms that transport electrons from cytoplasmic NADH to the respiratory chains  o 36 or 38, depending on the shuttle mechanisms that transport electrons from cytoplasmic NADH to the respiratory chains o 6 or 8, depending on the shuttle mechanisms that transport electrons from cytoplasmic NADH to the respiratory chains 64. Which enzyme takes part in the synthesis of triacylglycerols in the intestinal mucosa? (1 Point) o glycerol kinase o glycerol-3-phosphate acyltransferase o monoacylglycerol acyltransferase o glycerol-3-phosphate dehydrogenase o phosphatidate phosphohydrolase 65. How is the hydrogen from NADH transported from the cytoplasm to the mitochondria? 1) by the carnitine shuttle 2) by the glycerol-3-phosphate shuttle 3) by the malate-aspartate shuttle 4) by the citrate shuttle 5) by NADPH-oxidase (2 Points) o 1+2 o 2+5 o 2+3 o 1+4 o 3+5 66. The short electron transport chains in the liver perform: (1 Point) o non-specific hydroxylation to detoxify xenobiotics o specific hydroxylation in the pathway of steroid hormone synthesis o intensive heat production o oxidative deamination of amino acids o synthesis of saturated fatty acids 67. Which are the CORRECT statements? 1) bile acids are conjugated with glycine and taurine in the liver 2) deoxycholic and litocholic acids are primary bile acids 3) bile acids are transported in the blood by albumin 4) the main regulatory enzyme of bile acids synthesis is 1α- hydroxylase 5) bile acids are conjugated with glutamine and taurine in the liver (2 Points) o 2+4 o 1+3 o 3+5 o 2+3 o 1+4 68. Elastin is characterized by the presence of: 1) hydroxyproline and hydroxylysine amino acid residues 2) hydroxyproline but not hydroxylysine amino acid residues 3) a carbohydrate component 4) a structure called "desmosine" 5) a triple-helical structure (2 Points) o 2+4 o 2+3 o 3+5  o 1+2 o 1+5 69. Glycogen is: 1) a linear non-branched homopolysaccharide of glucose residues 2) a branched homopolysaccharide of glucose residues 3) a linear heteropolysaccharide of glucose and fructose residues 4) a branched heteropolysaccharide of glucose and fructose residues 5) the major storage form of glucose (2 Points) o 2+4 o 4+5 o 2+5 o 3+5 o 1+5 70. The heme is synthesized in: 1) erythrocytes 2) bone marrow 3) liver 4) mitochondria 5) mitochondria and cytoplasm (3 Points) o 2+3+5 o 1+3+5 o 1+2+4 o 1+3+4 o 2+3+4 71. Which of the following are reactions of the first phase of biotransformation of xenobiotics? 1) acetylation 2) hydroxylation 3) methylation 4) hydrolysis 5) sulphatation (2 Points) o 2+4 o 1+3 o 2+3 o 3+5 o 1+4 72. Which of the following statements about competitive inhibitors are TRUE? 1) the inhibitor is not a structural analogue of the substrate 2) the inhibitor is a structural analogue of the substrate 3) the inhibitor binds to the active site of the enzyme 4) the inhibitor binds to groups outside the active site of the enzyme 5) the inhibitory effect depends only on the concentration of the inhibitor (2 Points) o 2+4 o 1+5 o 4+5 o 1+3 o 2+3 73. How does the direct oxidative deamination of L-amino acids different from glutamate occur? 1) the oxidases act together with FMN 2) the oxidases act together with NAD 3) the released hydrogen enters the respiratory chain 4) the released hydrogen is transferred onto oxygen and hydrogen peroxide is formed 5) the obtained products are biogenic amines (2 Points) o 1+3 o 2+3 o 1+4 o 4+5 o 2+4 74. Which of the following compounds are macroergic? 1) phosphoenolpyruvate 2) glucose 6-phosphate 3) creatine phosphate 4) fructose 6-phosphate 5) glycerol 3-phosphate (2 Points) o 1+3 o 2+5 o 2+4 o 3+4 o 1+2 75. Which are the biologically active substances, secreted from platelet granules in the process of hemostasis? 1) thromboxane A2 (TXA2) 2) adenosine diphosphate (ADP) 3) serotonin 4) von Willebrand factor (factor VIII) 5) prostacyclin (PGI2) (3 Points) o 2+3+5 o 2+3+4 o 1+2+3 o 1+3+5 o 1+3+4 76. Adipocyte hormone-sensitive lipase is: 1) stimulated by adrenaline 2) stimulated by insulin 3) active in its phosphorylated form 4) active in its dephosphorylated form 5) it hydrolyzes monoacylglycerols (2 Points) o 1+4 o 1+5 o 1+3 o 2+3 o 2+4 77. Which are the differences between the oxidative phosphorylation at substrate level and in mitochondrial respiratory chains? 1) the respiratory chains usually provide less energy, less ATP molecules, respectively, compared to the oxidative phosphorylation at substrate level 2) the oxidative phosphorylation at substrate level synthesizes ATP no matter if there is or there isn’t oxygen 3) the respiratory chains are active only under aerobic conditions 4) the oxidation and phosphorylation are always tightly coupled at the level of substrates 5) the oxidation and phosphorylation can be easily uncoupled at the level of substrates (3 Points) o 1+2+5 o 2+3+4 o 1+2+4 o 2+3+5 o 1+2+3 78. Which of the amino acid residues can be involved in ionic bonds, which maintain the tertiary and quaternary structure of the proteins? 1) glutamyl 2) prolyl 3) arginyl 4) valyl 5) lysyl (3 Points) o 1+3+5 o 3+4+5 o 1+2+5 o 2+3+5 o 1+3+4 79. Choose the CORRECT statements about the hormone cortisol: 1) it is synthezied in zona glomeruloza of adrenal gland 2) it is synthezied in zona fasciculata of adrenal gland 3) its main effect on carbohydrate metabolism is to activate glycogenolysis 4) it is a feedback activator of the formation of CRH and ACTH 5) it is a feedback inhibitor of the formation of CRH and ACTH (2 Points) o 1+4 o 2+5 o 1+3 o 2+4 o 3+5 80. Which of the following statements about galactose metabolism are TRUE? 1) galactose degradation occurs in both liver and muscles 2) galactosemia caused by a defect in the enzyme galactose 1- phosphate uridyl transferase progresses in a severe way 3) galactokinase transfers a phosphate group onto the hydroxyl group at position 6 in the molecule of galactose 4) the reversible conversion of galactose to glucose requires UDP- derivatives 5) galactose degradation is an insulin dependent pathway (2 Points) o 1+4 o 2+4 o 2+3 o 3+5 o 1+2 81. Which of the following molecules are obtained in each of the cycles of β-oxidation? 1) NAPDH 2) NADH 3) FADH2 4) malonyl-CoA 5) Acetyl-CoA (3 Points) o 1+3+5 o 3+4+5 o 1+2+3 o 2+3+5 o 2+4+5 82. Which of the following statements are NOT true? 1) prostaglandins and thromboxanes are synthesized in the lipoxygenase pathway 2) prostaglandins and thromboxanes are synthesized in the cyclooxygenase pathway 3) nonsteroidal anti-inflammatory drugs (like aspirin, indomethacin, ibuprofen) inhibit selectively only the inducible isoform of the cyclooxygenase (COX-2) 4) activated phospholipase D hydrolyzes membrane phospholipids and produces arachidonic acid 5) leucotrienes and lipoxins are formed in the lipoxygenase pathway (3 Points) o 3+4+5 o 2+3+5 o 1+3+4 o 1+3+5 o 2+3+4 83. Which are the biological features of the protein “thermogenin”? 1) it is a membrane protein, embedded in the inner mitochondrial membrane 2) it is a membrane protein, located in the cell plasma membrane 3) it prevents electrons from passing through the membranes 4) thermogenin provides an alternative pathway for a proton flow through the inner mitochondrial membrane 5) its synthesis is under hormonal control (3 Points) o 2+3+5 o 3+4+5 o 1+4+5 o 1+3+5 o 2+4+5 84. Which are the CORRECT statements about the digestion of lipids? 1) TAGs are hydrolyzed by salivary and stomach lipase mainly in the small intestines 2) cholesteryl esters are hydrolyzed by acyl-CoA:cholesterol acyltransferase 3) bile acids are emulsifiers that are required in digestion 4) phospholipids are hydrolyzed by phospholipases 5) TAGs digested in the gastrointestinal tract are reesterified in enterocytes (3 Points) o 1+2+5 o 3+4+5 o 1+2+3 o 2+4+5 o 2+3+5 85. Metabolic changes common to type 1 and type 2 diabetes are: 1) hyperglycemia 2) ketoacidosis 3) hypertriacylglycerolemia (an increase in VLDL levels) 4) hyperchylomicronemia 5) hyperammonemia (2 Points) o 3+5 o 1+2 o 2+3 o 2+4 o 1+3 86. Which of the following enzymes participate in ketogenesis? 1) citrate lyase 2) HMG-CoA lyase 3) acyl-CoA dehydrogenase 4) acetyl-CoA carboxylase 5) 3-hydroxybutirate dehydrogenase (2 Points) o 2+4 o 2+5 o 2+3 o 1+3 o 3+4 87. Which of the following statements about vitamin K are TRUE? 1) vitamin K is a cofactor in the process of post-translational acetylation of lysyl residues in the polypeptide chains of histones 2) vitamin K is a cofactor in the post-translational carboxylation of glutamate residues (Glu), converting them to γ-carboxyglutamate (Gla) 3) vitamin K is a cofactor in the processes of post-translational hydroxylation of collagen 4) Vitamin K is required for the proper activation of some of the blood clotting factors 5) Vitamin K is needed for the proper maturation of some proteins involved in bone remodeling (3 Points) o 3+4+5 o 1+4+5 o 1+2+4 o 2+3+4 o 2+4+5 88. Cholesterol in the liver is involved in the formation of: 1) steroid hormones 2) prostaglandins 3) VLDL 4) cholic acid 5) taurochenodeoxycholic acid (3 Points) o 1+4+5 o 1+2+5 o 3+4+5 o 2+3+5 o 2+4+5 89. Carbamoyl phosphate synthetase II: 1) is located in the mitochondria 2) is located in the cytosol 3) is a regulatory enzyme 4) is activated allosterically by N-acetylglutamate 5) is inhibited allosterically by UTP (3 Points) o 1+4+5 o 2+3+4 o 1+3+4 o 2+3+5 o 3+4+5 90. Which enzymes catalyze the convertion of 1,3-bisphosphoglycerate to 3- phosphoglycerate in erythrocytes? 1) glycerol kinase 2) bisphosphoglycerate mutase 3) 2,3-bisphosphoglycerate phosphatase 4) glyceraldehyde-3-phosphate dehydrogenase 5) triose phosphate isomerase (2 Points) o 1+2 o 2+3 o 2+5 o 3+4 o 1+5 91. Cytochromes contain as a prosthetic group: (1 Point) o Vitamin C o FAD o iron-porphyrin ring (heme) o Vitamin A o NAD+ 92. Which of the following statements about ubiquinone (CoQ) are TRUE? 1) the presence of a long isoprenoid chain gives the molecule lipophilic properties 2) it is anchored to the membrane via a high-molecular weight protein 3) it acts as a low-molecular weight, non-protein bound redox- system 4) transports H-atoms from substrates in the mitochondrial matrix to the enzyme succinate dehydrogenase 5) CoQ is the li