This set of Biochemistry Multiple Choice Questions & Answers (MCQs) focuses on “ATP Synthesis-1”.
1. Which of the following is the prosthetic group of NADH dehydrogenase?
Explanation: NADH initially binds to complex I and transfers two electrons to the flavin mononucleotide (FMN) prosthetic group of the enzyme creating FMNH2.
2. Effect of valinomycin on oxidative phosphorylation does not involve _____________
a) pH gradient across the inner mitochondrial membrane decreases
b) Rate of flow of electrons increases
c) Rate of oxygen consumption increases
d) Net yield of ATP decreases
Explanation: pH gradient does not decrease.
3. If mitochondria were blocked at the site of NADH oxidation and were treated with succinate as substrate, what would the P : O ratio is?
a) Same as that normally produced by succinate
b) One more than normally produced by succinate
c) One less than normally produced by succinate
Explanation: If mitochondria were blocked at the site of NADH oxidation and were treated with succinate as substrate, the P : O ratio is the same as that normally produced by succinate.
4. If 2, 4-dinitrophenol 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
Explanation: Electron transfer is catalyzed from succinate or NADH to O2 but no ATP synthesis is coupled to this respiration.
5. If the oxidative phosphorylation was uncoupled in the mitochondria then there is a/an ____________
a) Decreased concentration of ADP in the mitochondria
b) Decreased oxidative rate
c) Increased inorganic phosphate in the mitochondria
d) Decreased production of heat
Explanation: If the oxidative phosphorylation was uncoupled in the mitochondria then there is an increased inorganic phosphate in the mitochondria.
6. If rotenone is added to the mitochondrial electron transport chain then ____________
a) Succinate oxidation remains normal
b) P: O ratio of NADH is reduced from 3:1 to 2:1
c) Oxidative phosphorylation is uncoupled at site I
d) Rate of NADH oxidation is diminished to two-thirds of its initial value
Explanation: If rotenone is added to the mitochondrial electron transport chain succinate oxidation remains normal.
7. Which of the following takes place in substrate level phosphorylation?
a) Oxidation of one molecule of substrate is linked to synthesis of more than one ATP molecule
b) High energy intermediate compounds cannot be isolated
c) Only mitochondrial reactions participate in ATP formation
d) Substrate reacts to form a product containing a high energy bond
Explanation: Substrate reacts to form a product containing a high energy bond.
8. Chemiosmotic hypothesis does not involve ____________
a) Only proton transport is strictly regulated, other positively charged ions can diffuse freely across the mitochondrial membrane
b) ATPase activity is reversible
c) Proton flow into the mitochondria depends on the presence of ADP and Pi
d) Electron transport by the respiratory chain pumps protons out of the mitochondria
Explanation: Not only proton transport but there is electron transport also.
9. Which one of the following is the one having highest redox potential?
Explanation: O2 has the highest redox potential.
10. Which of the following accepts only one electron?
a) Cytochrome b
b) Coenzyme Q
Explanation: Cytochrome b accepts only one electron.
Sanfoundry Global Education & Learning Series – Biochemistry.
To practice all areas of Biochemistry, here is complete set of 1000+ Multiple Choice Questions and Answers.