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Biochemistry MCQs Exam 2- PMU 2nd Year
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Questions in this quiz (46)
1The enzymes that catalyze oxidation and reduction reactions belong to class 1- oxidoreductases. Which are the subclasses of this class
- Aoxidases
- Bhydrolases
- Chydroperoxidases
- Doxygenases
- Etransferases
- Fdehydrogenases
2Which enzymes play major role in the formation of energy in the respiratory chain:
- Adehydrogenases
- Boxidases
- Coxygenases
- Dlyases
- Eligases
3Which of the following vitamins is not part of the multienzyme pyruvate dehydrogenase (PDH) complex?
- Alipoic acid
- Bthiamine
- Cbiotin
- Dniacin
- Eriboflavin
4Which of the following is TRUE:
- APDH is active in its dephospho form
- BPDH is inhibited by increased [NADH]/[NAD+] ratio
- CPDH is inhibited by increased [ATP]/ [ADP] ratio
- DPDH is activated by its product acetyl-CoA
5Which of the following is TRUE:
- Athe respiratory chain is localized in the inner mitochondrial membrane
- Bthe respiratory chain is localized in the cytosol
- Cthe respiratory chain generates energy (ATP) from the oxidation of the major foodstuffs: fats, carbohydrates, amino acids
- Dthe respiratory chain consists of four protein complexes embedded in the inner mitochondrial membrane
6Which of the following redox systems are not part of the respiratory chain:
- ACoQ/CoQ H2
- BNAD+/NADH
- Ccyt. P450
- Dcyt.c (Fe2+)/cyt.c (Fe3+)
- EFAD/FADH2
7Which of the following enzymes catalyze the reduction of O2 to H2O
- ANADH- CoQ oxidoreductase
- BCoQ- cyt c oxidoreductase
- Ccyt c oxidase
- DATP synthase
8Which of the following drugs and chemicals inhibit the electron transport in the respiratory chain:
- ABarbiturates
- BAntimycin A
- CCO
- DCN- (cyanide)
- ERotenone
- FOligomycin
9Which of the following about ATP synthase is TRUE:
- AATP synthase is embedded in the inner mitochondrial membrane, together with the other respiratory chain complexes
- BATP synthase is located in the intermembrane space
- CThe enzyme complex consists of F1 and F2 subcomplexes
- DBe flow of protons through ATP synthase causes the production of ATP
10Which of the following about citric acid cycle is TRUE:
- AThe cycle occurs in the cytosol
- BThe cycle occurs in the mitochondria
- CThe citric acid cycle is the final step for oxidation of carbohydrates, lipids and proteins
- DNADH and FADH2 obtained in the cycle are oxidized in the respiratory chain and ATP is formed
- EThe cycle occurs in the endoplasmic reticulum
11Which of the following enzymes participate in citric acid cycle:
- Ahexokinase
- Btransketolase
- Ccitrate synthase
- Dsuccinate dehydrogenase
- Epyruvate carboxylase
12Which of the following drugs and chemicals act as inhibitors of the electron transport in the respiratory chain:
- ARotenone
- BBarbiturates (e.g. amobarbital)
- COligomycin
- DCO and CN+
13Which of the following about citric acid cycle is TRUE:
- Athe initial reaction between acetyl-CoA and oxaloacetate to form citrate is catalyzed by aconitase
- Bthe α-ketoglutarate dehydrogenase complex requires the same cofactors as the PDH complex
- Csuccinate dehydrogenase contains FAD
- Das a result of the action of the dehydrogenases in the cycle 4 NADH and 1 FADH2 are produced per turn of the citric acid cycle
14Which of the following metabolites are not intermediates of the citric acid acid cycle:
- Afumarate
- Bsuccinyl-CoA
- Clactate
- Doxaloacetate
- Ephosphoenolpyruvate
15Which of the following about α-ketoglutarate dehydrogenase complex is TRUE:
- Ait is inhibited by ATP, NADH, succinyl-CoA
- Bit is activated by ATP, NADH, succinyl-CoA
- Cit is activated by Ca2+
- Done of its cofactors lipoic acid
16What is this?
- AATP
17Which of the following cytochromes are not part of the mitochondrial respiratory chain:
- Acyt. P450
- Bcyt. c1
- Ccyt. c
- Dcyt. b5
- Ecyt, a
18Which of the following statements about respiratory chains are true?
- AThey are located in the inner mitochondrial membrane
- BThey are located in the endoplasmic reticulum
- CThey should be coupled with ATP synthase
- DCyanides and CO can block forth complex of respiratory chain
- EBarbiturates can block second complex of respiratory chain
19Which of the following about Krebs cycle are true?
- AIt is a terminal common pathway for oxidation of all the substrates produced by the biological oxidation
- BFour metabolites from Krebs cycle donate H2 for the respiratory chains
- CSome of its metabolites can be used for biosynthesis
- DIt can occur both in aerobic and anaerobic conditions
20How many molecules of ATP will be provided by succinate dehydrogenase reaction from Krebs cycle?
- A0
- B1
- C2
- D3
- E4
21Examples of oxidative phosphorylation at substrate level are:
- AIsocitrate dehydrogenase reaction
- BOxidative decarboxylation of α-ketoglutarate
- CGlyceraldehyde-3-phosphate dehydrogenase reaction
- DMalate dehydrogenase reaction
- EEnolase reaction
22Which of the following statements oxidoreductases of biological oxidation are true?
- AThey are always two-component enzymes
- BThe Cofactor is always a redox system
- CThey can be simple enzymes
- DOxygenases are oxidoreductases
- EDehydrogenases are oxidoreductases
- FKinases are oxidoreductases
23All the cytochromes contain as prosthetic group
- ANAD
- BFAD
- CIron (Fe)- containing heme
- DBiotin
- EVit. C
24ADP/ATP system plays a key role in bioenergetics because:
- AATP is the richest in energy compound
- BATP can donate macroergic phosphoryl group to low-energy compounds and thus activate them
- CADP can affect macroergic phosphoryl group from richer than ATP energy compunds
- DATP has the middle position between the high and the low energy compounds according to the energy released during the hydrolysis of their bonds
25Which of the following component of respiratory chain act as H+ pumps?
- ACyt bc1 oxido-reductase
- BCyt NADH- Co Q oxido-reductase
- CCyt c oxidase
- DSuccinate - Co Q. oxido-redudase
26Which of the following statements about Pyruvate dehydrogenase complex are true
- AOne of its enzymes is pyruvate carboxylase
- BOne of its cofactors. is pyridoxal phosphate
- CIt is active in its dephosphorylated form
- DIt is located in the cytoplasm
- EIt is an example of oxidative phosphorylation at substrate level
27Which of the following act as uncouplers of the respiratory chain:
- ABarbiturates
- BAntimycin A
- COligomycin
- DThyroid Hormones
- E2.4-dinitrophenol
28Which of the following about ATP synthase is TRUE:
- AATP synthase is embedded in the inner mitochondrial membrane, together with the other respiratory chain complexes
- BATP Synthase is located in the intermembrane space
- CThe enzyme complex consists of F0 and F1 subcomplexes
- DThe flow of protons through ATP synthase causes the production of ATP
29Which of the following enzymes participate in citric acid cycle:
- Apyruvate kinase
- Bsuccinate dehydrogenase
- Ccitrate synthase
- Dfumarase
- Eglucokinase
30Which of the following about citric acid cycle represent its amphibolic role:
- Ait provides substrates for gluconeogenesis
- Bthe citric acid cycle is only for oxidation of acetyl-CoA
- Cit provides substrates for amino acids synthase
- Dthe citric acid cycle is the final step for oxidation of carbohydrates, lipids and proteins
- Eit takes part in fatty acid synthesis
31Which of the following are high energy compounds:
- ACreatine phosphate
- BGTP
- CAcetyl~CoA
- DGlucose-6-phosphate
- ECitrate
32Which of the following vitamins is not part of the multi-enzyme pyruvate dehydrogenase (PDH) complex?
- Alipoic acid
- Bthiamine
- Cniacin
- Dfolic acid
- Eriboflavin
33What is this?
- ACreatine Phosphate
34Which of the following is TRUE:
- Athe respiratory chain is localized in the inner mitochondrial membrane
- Bthe respiratory chain is localized in the endoplasmic reticulum
- Cthe respiratory chain generates energy (ATP) from the oxidization of the major foodstuffs: fats, carbohydrates, amino acids
- Done of the cytochromes in the respiratory chain is cyt. P450
35Respiratory chain:
- ACan function only in aerobic conditions
- BCan function independently on the presence of oxygen
- CIs located in the inner mitochondria! membrane
- DIs located in the outer mitochondrial membrane
- EIs located in the mitochondrial matrix
36Energy can be created in reactions catalyzed by:
- ATransferases
- BLygases
- COxidoreductases
- Dlsomerases
37Oxidative phosphorylation:
- ACan be executed only at substrate level
- BCan be executed only in respiratory chains
- CCan be executed both at substrate level and in respiratory chains
- DDoesn't create energy
- EIs the process of accumulation energy in ATP-form at the expense of oxidation of a substrate
38Which of the following statements about Pyruvate dehydrogenase complex are true?
- AIt is composed of 3 enzymes, working together with 5 Cofactors
- BIt located in the cytoplasm
- Cls one of the major donors of Acetyl Co A for Krebs cycle
- Dls activated by pyruvate, NAD and CoA, inhibited by NADH, and Acetyl Co A
- Els regulated through reversible covalent modification
39Which of the following about the processes of oxidation and reduction is true:
- AA chemical compound which is oxidized during the process of oxidation is known to be a reducer
- BA chemical compound which is oxidized during the process of oxidation is an oxidizer
- CA chemical compound which is reduced during the process of reduction is known to be a reducer
- DA chemical compound which is reduced during the process of reduction is known to be an oxidizer
- EOxidation and reduction are coupled processes, mostly
40Which of the following is low energy phosphate
- APhosphoenolpyruvate
- BCreatine Phosphate
- CGlucose 6-phosphate
- DFructose 6-phosphate
- EGlycerol 3-phosphate
41Which of the following about FAD and FMN is true?
- AFAD and FMN are vitamin PP derivatives
- BFAD and FMN are vitamin B2 derivatives
- CFAD and FMN are vitamin B6 derivatives
- DFAD and FMN participate in bioenergetics as electron carriers
- EFAD and FMN are coenzymes of enzymes called dehydrogenase and oxidases mostly
42Which of the following is true?
- Ahydroperoxidases are two types of enzymes: peroxidases and catalase
- Bhydroperoxidases use hydrogen peroxide as electron donor
- Chydroperoxidases contain NAD or NADP as coenzyme
- Dhydroperoxidases contain FAD or FMN as coenzyme
- Ehydroperoxidases contain heme or protoheme as coenzyme
43How many molecules of ATP are synthesized in the citric acid cycle per turn?
- A1
- B6
- C12
- D36
- E38
44Complex 3 of the respiratory chain
- Aaccepts electrons and protons from coenzyme Q
- Bis consisted of enzymes which operate with cytochromes as coenzymes
- Ctransfers electrons and protons from coenzyme Q to cytochrome C
- Dtransfers electrons and protons directly to oxygen
- Eis "loaded" with electrons and protons from different substrates via NAD
45How many molecules of NAD are reduced per turn in the citric acid cycle?
- A1
- B2
- C3
- D4
- E5
46Which of the following is true?
- Aall enzymes of citric acid cycle are placed in mitochondria
- Bthere is an enzyme, involved in the citric acid cycle, which is anchored to the inner mitochondrial membrane
- Call enzymes of citric acid cycle are placed in cytosol
- Dall enzymes of the citric acid cycle are place in the mitochondrial matrix
- Esome of the enzymes of the citric acid cycle are places in the cytosol and other are placed in mitochondrion
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