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Multiple Choice Questions

Q.1- If the mitochondria were blocked at the site of NADH oxidation and were treated with succinate as substrate, what would the P: O ratio is?

A. Zero

B. One less than normally produced by succinate

C. Same as that normally produced by succinate

D. One more than normally produced by succinate

E. Higher than normal because of the excessive heat produced from uncoupling

Q.2- If the oxidative phosphorylation was uncoupled in the mitochondria, what would one expect?

A. A decreased concentration of ADP in the mitochondria

B. Increased inorganic phosphate in the mitochondria

C. A decreased oxidative rate

D. A decreased production of heat

E. Increased transport of ADP from the cytosol to the mitochondrial matrix

Q.3- If the rotenone is added to the mitochondrial electron transport chain:

A. P: O ratio of NADH is reduced from 3:1 to 2:1

B. Rate of NADH oxidation is diminished to two- thirds of its initial value

C. Succinate oxidation remains normal

D. Oxidative phosphorylation is uncoupled at site I

E. Electron flow is inhibited at site II

Q.4- If 2, 4 dinitro phenol is added to tightly coupled mitochondria that are actively oxidizing succinate:

A. Electron flow will continue but ATP synthesis will not occur

B. Electron flow will continue but ATP synthesis will be increased

C. Electron flow will cease, but ATP synthesis will continue

D. Both Electron flow and ATP synthesis will be ceased

E. Subsequent addition of Oligomycin will cause ATP hydrolysis

Q.5- The prosthetic group of NADH dehydrogenase:

A. FMN

B. NADH

C. FAD

D. NADPH

E. Iron

Q.6- In substrate level phosphorylation

A. The substrate reacts to form a product containing a high energy bond

B. ATP synthesis is linked to dissipation of proton gradient

C. High energy intermediate compounds cannot be isolated

D. Oxidation of one molecule of substrate is linked to synthesis of more than one ATP molecule

E. Only mitochondrial reactions participate in ATP formation

Q.7- The chemiosmotic hypothesis involves all of the following except

A. A membrane impermeable to protons

B. Electron transport by the respiratory chain pumps protons out of the mitochondria

C. Proton flow in to the mitochondria depends on the presence of ADP and Pi

D. ATPase activity is reversible

E. Only proton transport is strictly regulated, other positively charged ions can diffuse freely across the mitochondrial membrane

Q.8- The effect of Valinomycin on oxidative phosphorylation involves all of the following except-

A. The net yield of ATP decreases

B. Rate of oxygen consumption increases

C.  Excessive heat is released

D. pH gradient across the inner mitochondrial membrane decreases

E. The rate of flow of electrons increases

Q.9- Which of the following ETC components accept only one electron?

A. Coenzyme Q

B. Cytochrome b

C. FAD

D.FMN

E. O2

Q.10- Which of the following has highest redox potential in the respiratory chain?

A. O2

B. Ubiquinone

C. NAD

D.FMN

E. FAD

Key to answers

1)-C, 2)-B, 3)-C, 4)-A, 5)-A, 6)-A, 7)-E, 8)-D, 9) – B, 10)-A.

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Q.1- All of the following except one are NAD+ requiring enzymes –

A. Acyl co A dehydrogenase

B. Glyceraldehyde-3-P dehydrogenase

C. Pyruvate dehydrogenase complex

D. Malate dehydrogenase

E. Lactate dehydrogenase

Q.2- Which one of the following enzymes catalyzes substrate level phosphorylation in TCA cycle

A. Malate dehydrogenase

B. Succinate Thiokinase

C. Succinate dehydrogenase

D. Alpha keto dehydrogenase complex

E. Isocitrate dehydrogenase

Q.3- The major metabolic consequence of perturbation of the electron transfer in mitochondria is which of the following?

A. Increased production of NADPH

B. Increased oxidation of NADH

C. Increased reduction of O2 to H2O

D. Decreased regeneration of NAD+

E. Decreased reduction of FAD

Q.4- An unskilled worker in a water garden/plant nursery was sent to sweep up a spill of a white powder in the storage shed. Later he was found with labored breathing and convulsions. On further examination, the white powder was identified as rotenone. Respiratory distress is induced on rotenone exposure because it inhibits the complex that catalyzes which of the following?

A. Electron transfer from NADH to coenzyme Q

B. Oxidation of coenzyme Q

C. Reduction of cytochrome c

D. Electron transfer from cytochrome c to cytochrome a1/a3

E. Electron transfer from cytochrome a1/a3 to oxygen

Q.5- Which of the following procedures best describes the emergency intervention for cyanide poisoning?

A. Decrease the partial pressure of oxygen

B. Treatment with nitrites to convert hemoglobin to methemoglobin.

C. Treatment with thiosulfate to form thiocyanate

D. Use of N-acetyl cysteine taken orally

E. Use of Antioxidants

Q.6- Inhibition of oxidative phosphorylation by cyanide ion leads to increases in which of the following?

A. Gluconeogenesis to provide more glucose for metabolism

B. Transport of ADP into the mitochondria

C. Utilization of fatty acids substrates to augment glucose utilization

D. Utilization of ketone bodies for energy generation

E. Lactic acid in the blood causing acidosis

Q.7- 27-year-old male with acute appendicitis undergoing a halothane inhaled anesthetic with acute onset of hyperthermia, tachypnea, respiratory acidosis, hyperkalemia, and family history of similar events. The tentative diagnosis is malignant hyperthermia (MH). Which of the following processes gets affected by Halothane?

A. Inhibition of NADH-Q oxidoreductase (Complex I)

B. Inhibition of Q-cytochrome c oxidoreductase (Complex III)

C. Inhibition of succinate Q reductase (Complex II)

D. Inhibition of ADP/ATP transporter

E. Uncoupling of oxidative phosphorylation

Q.8- The rate of respiration of mitochondria can be controlled by the availability of:

A. ADP

B. ATP

C. FMN

D.FAD

E. NAD +

Q.9- Atractyloside inhibits oxidative phosphorylation by inhibiting:

A. NADH-Q oxidoreductase (Complex I)

B. Q-cytochrome c oxidoreductase (Complex III)

C. Succinate Q reductase (Complex II)

D. ADP/ATP transporter

E. Cytochrome a1-a3 oxidase

Q.10- The enzyme that catalyzes the direct transfer and incorporation of oxygen into a substrate molecule is known as:

A. Oxidase

B. Oxygenase

C. Peroxidase

D. Reductase

E. Hydratase

Key to Answers

1)-A, 2) -B, 3) – D, 4)-A, 5)-B, 6)-E, 7)-E, 8)-A, 9)-D, 10)-B

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Q.1- Choose a site along the electron transport chain out of the following that is not coupled to ATP synthesis-

a) NADH- coenzyme Q (CoQ) reductase

b) Succinate-Co Q reductase

c) Cytochrome bc1 reductase

d) Cytochrome oxidase

e) None of the above.

Q.2- Choose a statement out of the following that best describes the uncouplers of oxidative phosphorylation-

a) Uncouple ATP synthesis with phosphoenol pyruvate

b) Uncouple ATP/ADP translocation

c) Uncouple electron transport from oxygen reduction

d) Uncouple electron transport with ATP synthesis

e) Uncouple ATP synthesis with phosphoglycerate

Q.3- Which of the following statements best describes the mechanism of action of Oligomycin ?

a)It inhibits NADH dehydrogenase

b) It is an uncoupler of oxidative phosphorylation

c) It inhibits ATP/ADP transporter

d) It is an inhibitor of cytochrome oxidase

e) It blocks the flow of protons through ATP synthase complex

Q.4- ADP transport in to the mitochondrial matrix–

a) is an active transport process

b) is directly inhibited by valinomycin

c) is carried out through a shuttle present in outer mitochondrial membrane

d) is accompanied by ATP export from the mitochondrial matrix

e) is inhibited by Rotenone

Q.5- Which of the following enzymes catalyzes the conversion of Hydrogen peroxide to water ?

a) Super oxide dismutase

b) Cytochrome P 450

c) Catalase

d) Hydratase

e) Dioxygenase

Q.6- Which of the following ETC components accepts only one electron ?

a) Oxygen

b) FMN

c) FAD

d) Cytochrome b

e) Coenzyme Q

Q.7- Which of the following is a component of Succinate dehydrogenase in Electron transport chain ?

a) Niacin

b) FMN

c) FAD

d) Coenzyme Q

e) Lipoic acid

Q.8- MELAS is a mitochondrial disorder characterized by mitochondrial encephalopathy , lactic acidosis and stroke-like episode. It is an inherited condition due to NADH:Q oxidoreductase (Complex I) or cytochrome oxidase (Complex IV) deficiency, caused by a mutation in mitochondrial DNA and may be involved in Alzheimer’s disease and diabetes mellitus. Due to lack of functional mitochondria, what would be the net ATP that would be produced from one molecule of Glucose ?

a) 1

b) 2

c) 4

d) 8

e) 0

Q.9- An 18- year -old cricket player sustains a compound fracture on the field. He is taken for surgery, during which anesthesiologist notes a significantly increased body temperature (104OF). There is suspicion of malignant hyperthermia. Which of the following components of ETC is likely to be responsible for this phenomenon ?

a) Complex I

b) Complex II

c) Complex III

d) Complex IV

e) ATP synthase complex

Q.10- A 43- year-old woman diagnosed with early stage breast cancer elects to have a lumpectomy followed by radiation therapy because this regimen has been shown to be equivalent to mastectomy in such patients. Radiations work in part by-

a) Inhibiting NADH – cytochrome C reductase

b) Inhibiting cytochrome b-c1 complex

c) Generating reactive oxygen species

d) Oxidizing glutathione

e) Inhibiting ATP synthase complex

Q.11- An -8 year-old boy is seen by an ophthalmologist for difficulties in seeing in all visual fields as well as slow eye movements. The ophthalmologist finds pigmentary retinopathy and ophthalmoplegia. The child is suspected to have Kearns- Sayre syndrome, a disorder due to a mutation in complex II of ETC. The electron transport from which substance would be impaired ?

a) Malate

b) Isocitrate

c) Succinate

d) Pyruvate

e) Alpha keto glutarate

Q.12- A 63- year-old man with a strong family history of Parkinson’s disease begins to show the signs of the disease “pin rolling tremors”. He visits his neurologist, who guides him about the recent research about coenzyme Q, that may stall the development of the disease. This component of ETC normally –

a) receives electrons directly from NADH

b) receives electrons directly from complex IV

c) receives electrons directly from FMN

d) transports ATP to the cytoplasm

e) Contains heme

 

Key to answers-

1)- b, 2)- d, 3)- e, 4)- d, 5)- c, 6)- d, 7)- c, 8)- b, 9)-e, 10)-c , 11)-c , 12)- c

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1. Dehydrogenases catalyze the transfer of hydrogen from one substrate to another in a coupled oxidation-reduction reaction .These dehydrogenases are specific for their substrates but often utilize common coenzymes or hydrogen carriers, e.g. NAD+. Which out of the following is not a niacin ( NAD+) dependent dehydrogenase ?

a) Pyruvate dehydrogenase

b) Glycerol-3-P dehydrogenase( Mitochondrial )

c) Glyceraldehyde-3-P dehydrogenase

d) Lactate dehydrogenase

e) Alpha keto glutarate dehydrogenase

2. The cytochromes are iron-containing hemoproteins in which the iron atom oscillates between Fe3+ and Fe2+ during oxidation and reduction. Most of the cytochromes of the electron transport chain are classified as dehydrogenases . Which out of the following cytochromes is not a dehydrogenase ?

a) NADH-Q oxidoreductase (Complex I)

b) Q-cytochrome c oxidoreductase (Complex III)

c) cytochrome c oxidase (Complex IV)

d) Succinate Q reductase (Complex II)

e) cytochrome c

3. A 2-year – old child has been brought to pediatric OPD with the complaint of passage of black colored urine. A probable diagnosis of Alkaptonuria has been made. Alkaptonuria is a congenital disorder of deficiency of Homogentisic acid oxidase. Homogentisic acid oxidase is an enzyme of tyrosine metabolic pathway and functionally it is –

a) A dehydrogenase

b) An oxidase

c) Mono oxygenase

d) Di oxygenase

e) Hydroperoxidase

4. A 23 -year -old male has been brought to medical OPD with jaundice and passage of dark colored urine. History reveals that he took antibiotic sulphonamides for a sore throat and ever since he developed the symptoms. There is history of previous such episodes also . A probable diagnosis of Glucose-6-P dehydrogenase deficiency has been made. NADPH  produced from the activity of this enzyme is required for the reductive processes in the body. Reduction of oxidized glutathione is one of such processes. G-SH (Reduced glutathione) is required for the activity of a selenium containing peroxidase, an enzyme required for the maintenance of the integrity of the red blood cell membrane. The reduced activity of this enzyme is responsible for hemolytic anemia in such patients. Which of the following is not a product of this enzyme catalyzed reaction ?

a) Hydrogen peroxide

b) Water

c) Oxidized substrate

d) NADP+

e) Oxidized glutathione

5. A chronic alcoholic has been brought to medical emergency. Blood biochemistry reveals lactic acidosis. Deficiency of pyruvate dehydrogenase complex is suspected. Pyruvate dehydrogenase complex (PDH complex) is a multienzyme complex, that requires, thiamine, Pantothenic acid, lipoic acid, riboflavin and niacin for its action and catalyzes the oxidative decarboxylation of pyruvate to from acetyl co A. During this process of oxidation what is the expected P:O ratio ?

a) 3:1

b) 6:1

c) 4:1

d) 12 :1

e) 38 :1

6. For each acetyl Co-A oxidized by the citric acid cycle, what is the energy gain by  substrate level phosphorylation ?

a) 2 ATP

b) 4 ATP

c) 6 ATP

d) 1 ATP

e) Zero ATP

7.Which of the following enzymes catalyzes a reaction with the resultant  P:O ratio of 2:1 ?

a) Glycerol-3-P-dehydrogenase (Cytosolic)

b) Succinate dehydrogenase

c) Malate dehydrogenase

d) Lactate dehydrogenase

e) Glucose-6-P dehydrogenase

8. Which of the following compounds inhibits oxidative phosphorylation by inhibiting the transporter of ADP into and ATP out of the mitochondrion ?

a) Malonate

b) Oxamate

c) Atractyloside

d) Barbiturates

e) Cyanide

9. The energy of oxidation is initially trapped as a high-energy phosphate compound and then used to form ATP. Which of the following intermediates of glycolysis is a high energy compound ?

a) Fructose-6-P

b) Glyceraldehyde-3-P

c) Fructose-1,6 bisphosphate

d) Glucose-6-P

e) Phosphoenol pyruvate

10. ATP is a nucleotide consisting of an adenine, a ribose, and a triphosphate unit. The active form of ATP is usually a complex of ATP with Mg2+ or Mn2+ . ATP is an energy-rich molecule because its triphosphate unit contains two phosphoanhydride bonds. A large amount of free energy of the amount ——– approximately  is liberated when ATP is hydrolyzed to adenosine diphosphate (ADP) and orthophosphate (Pi) .

a) 12.3 kcal/mol

b) 10.9 kcal/mol

c) 6.8 kcal/mol

d) 7.3 kcal/mol

e) 8.3 kcal/mol

11.  Which of the components of electron transport chain does not contain Iron sulfur center?

a) NADH dehydrogenase complex

b) Cytochrome a-a3 oxidase

c) Succinate dehydrogenase

d) Cytochrome bc1-c reductase

12. Aspirin in a high dosage produces hyperthermia, despite the fact that it is itself an antipyretic agent. The reason for this effect is-

a) Aspirin affects hypothalamic functions

b) It uncouples oxidative phosphorylation

c) It stimulates metabolism

d) It is itself metabolized to high energy compound

e) All of the above.

13. Choose the incorrect statement  out of the following about complete oxidation of glucose in the presence of oxygen-

a) In RBC s nearly 90% of the energy is obtained via oxidative phosphorylation

b) 1,3 Bisphosphoglycerate is a high energy compound

c) The conversion of phosphoenol pyruvate to pyruvate  yields 2 ATP

d) Net energy output in skeletal muscle is 36 ATP

e) 10 % of the total energy is obtained by substrate level phosphorylation in most tissues

14. Choose the correct statement out of the following  about Iron Sulfur centers-

a) Iron-sulfur proteins (non-heme iron proteins, Fe-S)  are found in Complexes IV

b) These may contain five  iron atoms linked to inorganic sulfur atoms

c) Iron may be linked through  cysteine-SH groups to the protein

d) The Fe-S take part in two electron transfer reactions

e) The Fe atom always  remains in the reduced form ( Fe2+) .

Key to answers- 1)-b , 2)-c, 3)-  d, 4)- a, 5- b, 6)-a, 7)-b, 8)-c, 9)-e,10)-d, 11)-b, 12-b, 13)-a, 14)-c.

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Q.1-Out of the following respiratory chain components indicate which  one is a mobile carriers of electrons?

a) Cytochrome oxidase

b) NADH-Q reductase

c) Ubiquinone

d) Succinate dehydrogenase                                             

Q.2-Choose the incorrect statement about redox potential

a) The redox potential of a system (E0) is usually compared with the potential of the hydrogen electrode

b) The components of electron transport chain are organized in terms of their redox potential.

c) NADH/NAD+ redox pair has the least redox potential of -0.42 volts

d) Oxygen/H2O redox pair has the highest redox potential of +.82 volts

Q.3-All are flavoproteins except one, choose the odd one out

a) Xanthine oxidase

b) NADH dehydrogenase –Q reductase

c) Succinate dehydrogenase

d) Cytochrome c                                                               

Q.4-All except one are incorrect about oxidases-

a) Oxidases catalyze reactions involving hydrogen peroxide.

b) Oxidases catalyze reaction using oxygen as a hydrogen acceptor

c) Oxidases catalyze  reactions using Niacin as coenzyme

d) Oxidases catalyze reactions of direct incorporation of oxygen in to the substrate

Q.5-All of the following are NAD+ requiring enzymes except one –

a) Acyl co A dehydrogenase

b) Glyceraldehyde-3-P dehydrogenase

c) Pyruvate dehydrogenase complex

d) Malate dehydrogenase

Q.6-One out of the following enzymes can utilize both NAD+ and NADP+as a coenzyme

a) Aldehyde dehydrogenase

b) Alcohol dehydrogenase

c) Glutamate dehydrogenase

d) Glycerol-3-P dehydrogenase

Q.7-Which out of the following components is not a haemo protein?

a) Catalase

b) Peroxidase

c) Ubiquinone

d) Cytochrome c                                                              

Q.8-Dioxygenases catalyze the incorporation of both atoms of oxygen in to the substrate. Which out of the following is a dioxygenase?

a) Tryptophan pyrrolase

b) Lactate dehydrogenase

c) Cytochrome oxidase

d) L- amino acid oxidase                                                  

Q.9 -Which of the components of electron transport chain does not contain Iron sulfur center?

a) NADH dehydrogenase complex

b) Cytochrome a-a3 oxidase

c) Succinate dehydrogenase

d) Cytochrome bc1-c reductase                                        

Q.10-A child has accidentally ingested a chemical and has presented with high fever.The chemical is known to affect ATP formation in electron transport chain,which out of the following could cause the similar manifestations

a) Cyanide

b) Malonate

c) 2,4 dinitrophenol

d) Rotenone                                                                    

Q.11-A 32- year female working in a laboratory consumed cyanide and was rushed to hospital. She was declared dead upon reaching the hospital. Cyanide is a known inhibitor of Electron Transport chain (ETC). Which complex of ETC might have been inhibited?

a) Complex I

b) Complex II

c) Complex III

d) Complex IV        

Q.12-The enzymes of mitochondrial matrix include all except

a) Enzymes of fatty acid oxidation

b) Creatine kinase

c) Enzymes of TCA cycle

d) Pyruvate dehydrogenase complex

Q.13-Patients with inherited defects of mitochondria involving components of the respiratory chain and oxidative phosphorylation present with all except

a) Myopathy

b) Lactic acidosis

c) Encephalopathy

d) Hepatomegaly

Q.14-The inner mitochondrial membrane is rich in which of the following phospholipids?

a) Cardiolipin

b) Lecithin

c) Cephalin

d) None of the above                                                       

Q.15-All are true about ATP synthase complex, except

a) F1projects into the inter membranous space

b) Fspans the membrane and forms a proton channel.

c) Fis inhibited by Oligomycin

d) F1contains the phosphorylation mechanism                     

Q.16-The energy yield during the conversion of succinate to Fumarate is-

a) 2ATP

b) 1ATP

c) 3ATP

d) No ATP                                                                     

Q.17-Which of the following best describes the biochemical basis of hyperthermia associated with Aspirin toxicity

a) Increased fatty acid oxidation

b) Increased muscular activity

c) Elevated consumption of ATP to support muscle contraction

d) Uncoupling of oxidative phosphorylation                       

Q.18-The electron flow from complex I to complex III is through

a) Cytochrome c

b) Ubiquinone

c) Complex II

d) Complex IV

Q.19-Which of the following best describes the toxicity associated with Atractyloside

a) Acts as an inhibitor of ETC

b) Acts as an uncoupler

c) Acts as an inhibitor of ATP/ADP transporter

d) Inactivates ATP synthase complex

Q.20- For each H2O molecule formed in ETC around ———– protons are pumped into inter membranous space

a) 4

b) 2

c) 10

d) None of the above

Q.21- Which one of the following enzymes catalyzes substrate level phosphorylation in TCA cycle

a) Malate dehydrogenase

b) Succinate Thiokinase

c) Succinate dehydrogenase

d) Alpha keto glutarate dehydrogenase complex

Q.22- Which of the following occurs in non shivering thermogenesis?

a) Glucose is oxidized to lactate

b) Fatty acids uncouple oxidative phosphorylation

c) ATP is spent for heat production

d) Glycogen is excessively degraded

Q.23- One out of the following is an inhibitor of complex I

a) Rotenone

b) H2S

c) BAL

d) CN

Q.24- Which out of the following statements concerning the components of electron transport chain is true?

a) Oxygen directly oxidizes Cytochrome c

b) Succinate dehydrogenase directly reduces Cytochrome c

c) All of the components are embedded in the inner mitochondrial membrane

d) Cyanide does not inhibit proton pumping but inhibits ETC

Q.25- The free energy released during the transport of a pair of electrons in electron transport chain is

a) 7.3 Kcal/mol

b) 52.6 Kcal/mol

c) 21.9 Kcal/mol

d) None of the above

Key to answers

1)- (c), 2)-(c), 3)- (d), 4)- (b), 5)- (a), 6)- (c), 7)- (c), 8)- (a), 9)- (b),10)- (c),11)- (d), 12)- (b),13)- (d),14)- (a),

15) (a), 16)- (a),17)- (d),18)- (b),19)- (c), 20)-(c), 21)- (b), 22)- (b), 23)- (a), 24)- (d), 25)- (b). 

 


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Q.1- Out of the following respiratory chain components indicate which  one is a mobile carriers of electrons?
a) Cytochrome oxidase
b) NADH-Q reductase
c) Ubiquinone
d) Succinate dehydrogenase
Q.2- Choose the incorrect statement about redox potential
a) The redox potential of a system (E0)is usually compared with the potential of the hydrogen electrode
b) The components of electron transport chain are organized in terms of their redox potential.
c) NADH/NAD+ redox pair has the least redox potential of -0.42 volts
d) Oxygen/H2O redox pair has the highest redox potential of +.82 volts.
Q.3- All are flavoproteins except one, choose the odd one out-
a) Xanthine oxidase
b) NADH dehydrogenase –Q reductase
c) Succinate dehydrogenase
d) Cytochrome c
Q.4-All except one are incorrect about oxidases-
a) Oxidases catalyze reactions involving hydrogen peroxide.
b) Oxidases catalyze reaction using oxygen as a hydrogen acceptor
c) Oxidases catalyze  reactions using Niacin as coenzyme
d) Oxidases catalyze reactions of direct incorporation of oxygen in to the substrate.
Q.5- All of the followings are NAD+requiring enzymes except one –
a) Acyl co A dehydrogenase
b) Glyceraldehyde-3-P dehydrogenase
c) Pyruvate dehydrogenase complex
d) Malate dehydrogenase
Q.6- One out of the following enzymes can utilize  both NAD+ or NADP+ as a coenzyme-
a) Aldehyde dehydrogenase
b) Alcohol dehydrogenase
c) Glutamate dehydrogenase
d) Glycerol-3-P dehydrogenase
Q.7- Which out of the following components is not a haemo protein?
a) Catalase
b) Peroxidase
c) Ubiquinone
d) Cytochrome c
Q.8-Dioxygenases catalyze the incorporation of both atoms of oxygen in to the substrate. Which out of the following is a dioxygenase?
a) Tryptophan pyrrolase
b) Lactate dehydrogenase
c) Cytochrome oxidase
d) L- amino acid oxidase
Q.9- Which of the components of electron transport chain does not contain Iron sulfur center?
a) NADH dehydrogenase complex
b) Cytochrome a-a3 oxidase
c) Succinate dehydrogenase
d) Cytochrome bc1-c reductase
Q.10- A child has accidentally ingested a chemical and has presented with high fever. The chemical is known to affect ATP formation in electron transport chain , which out of the followings could cause the similar manifestations
a) Cyanide
b) Malonate
c) 2,4 dinitrophenol
d) Rotenone
Q.11- A 32- year female working in a laboratory consumed cyanide and was rushed to hospital .She was declared dead upon reaching  the hospital.Cyanide is a known inhibitor of Electron Transport chain (ETC). Which complex of ETC might have been inhibited?
a) Complex I
b) Complex II
c) Complex III
d) Complex IV
Q.12-The enzymes of mitochondrial matrix include all except-
a) Enzymes of fatty acid oxidation
b) Creatine kinase
c) Enzymes of TCA cycle
d) Pyruvate dehydrogenase complex
Q.13-Patients with inherited defects of mitochondria involving components of the respiratory chain and oxidative phosphorylation present with all except-
a) Myopathy
b) Lactic acidosis
c) Encephalopathy
d) Hepatomegaly
Q.14- The inner mitochondrial membrane is rich in which of the following phospholipids?
a) Cardiolipin
b) Lecithin
c) Cephalin
d) None of the above
Q.15- All are true about ATP synthase complex, except-
a) F1 projects into the inter membranous space
b) F0 spans the membrane and forms a proton channel.
c) F0 is inhibited by Oligomycin
d) F1contains thephosphorylation mechanism
Q.16- The energy yield during the conversion of succinate to Fumarate is-
a) 2 ATP
b) 1 ATP
c) 3 ATP
d) No ATP
Q.17- Which of the following best describes the biochemical basis of hyperthermia associated with Aspirin toxicity
a) Increased fatty acid oxidation
b) Increased muscular activity
c) Elevated consumption of ATP to support muscle contraction
d) Uncoupling of oxidative phosphorylation
Q.18-The electron flow from complex I to complex III is through
a) Cytochrome c
b) Ubiquinone
c) Complex II
d) Complex IV
Q.19-Which of the followings best describes the toxicity associated with Atractyloside
a) Acts as an inhibitor of ETC
b) Acts as an uncoupler
c) Acts as an inhibitor of ATP/ADP transporter
d) Inactivates ATP synthase complex
Q.20- For each H2O molecule formed in ETC around ———–  protons are pumped into
inter membranous space
a) 4
b) 2
c) 10
d) none of the above
Q.21- Which one of the following enzymes catalyzes substrate level phosphorylation in TCA cycle
a) Malate dehydrogenase
b) Succinate Thiokinase
c) Succinate dehydrogenase
d) Alpha keto glutarate dehydrogenase complex
Q.22- Which of the following occurs in non shivering thermogenesis?
a) Glucose is oxidized to lactate
b) Fatty acids uncouple oxidative phosphorylation
c) ATP is spent for heat production
d) Glycogen is excessively degraded
Q.23- One out of the following is an inhibitor of complex I
a) Rotenone
b) H2S
c) BAL
d) CN
Q.24- Which out of the following statements concerning the components of electron transport chain is true?
a) Oxygen directly oxidizes Cytochromec
b) Succinate dehydrogenase directly reduces Cytochrome c
c) All of the components are embedded in the inner mitochondrial membrane
d) Cyanide does not inhibit proton pumping but inhibits ETC
Q.25- The free energy released during the transport of a pair of electrons in electron transport chain is-
a) 7.3 Kcal/mol
b) 52.6 Kcal/mol
c) 21.9 Kcal/mol
d) None of the above
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