MCQOPTIONS
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MCQOPTIONS
This section includes 195 Mcqs, each offering curated multiple-choice questions to sharpen your Biochemistry knowledge and support exam preparation. Choose a topic below to get started.
| 1. |
In what form does the product of glycolysis enter the TCA cycle? |
| A. | AcetylCoA |
| B. | Pyruvate |
| C. | NADH |
| D. | Glucose |
| Answer» B. Pyruvate | |
| 2. |
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 |
| Answer» E. | |
| 3. |
The pigment used in human vision is |
| A. | Retinal |
| B. | Vitamin A |
| C. | Ferredoxin |
| D. | Beta-carotene |
| Answer» B. Vitamin A | |
| 4. |
The followings are the products of the light reactions of photosynthesis except |
| A. | ATP |
| B. | oxygen |
| C. | NADPH |
| D. | glucose |
| Answer» E. | |
| 5. |
The regulation of oxidative phosphorylation depends on |
| A. | Magnitude of ion motive force |
| B. | Magnitude of electron motive force |
| C. | Magnitude of proton motive force |
| D. | None of the mentioned |
| Answer» D. None of the mentioned | |
| 6. |
A water-soluble protein that carries one electron present in mitochondria is |
| A. | PQʙ |
| B. | Q |
| C. | Cytochrome c |
| D. | Plastocyanin |
| Answer» D. Plastocyanin | |
| 7. |
Carbon dioxide is reduced in |
| A. | noncyclic photophosphorylation |
| B. | the Calvin cycle |
| C. | the light reactions |
| D. | both light and dark reactions |
| Answer» C. the light reactions | |
| 8. |
Maximum energy per gram on oxidation is yielded from |
| A. | Starch |
| B. | Fat |
| C. | Glycogen |
| D. | Protein |
| Answer» C. Glycogen | |
| 9. |
Which of the following serves as a reactant in photosynthesis and a product in cellular respiration? |
| A. | O₂ |
| B. | CO₂ |
| C. | Sunlight |
| D. | ATP |
| Answer» C. Sunlight | |
| 10. |
Oxidative phosphorylation is to respiration as __________ is to photosynthesis |
| A. | carbon fixation |
| B. | electron transport chain |
| C. | light capture by chlorophyll |
| D. | reduction of NADPH |
| Answer» C. light capture by chlorophyll | |
| 11. |
What process in cellular respiration is essentially the reverse of carbon fixation in photosynthesis? |
| A. | Glycolysis |
| B. | Citric acid cycle |
| C. | Oxidative phosphorylation |
| D. | Alcohol fermentation |
| Answer» C. Oxidative phosphorylation | |
| 12. |
Which of the following describes the complete route by which electrons flow H₂O to NADP⁺? |
| A. | Z scheme |
| B. | A scheme |
| C. | B scheme |
| D. | X scheme |
| Answer» B. A scheme | |
| 13. |
Oxidative stress (in humans) is not involved in the development of |
| A. | Cancer |
| B. | Parkinson’s disease |
| C. | Heart failure |
| D. | Kidney failure |
| Answer» E. | |
| 14. |
What is the proportion of ATP produced by oxidative phosphorylation? |
| A. | 60% |
| B. | 70% |
| C. | 80% |
| D. | 90% |
| Answer» B. 70% | |
| 15. |
Which one of the following is a product of both cyclic and noncyclic photophosphorylation? |
| A. | NADPH |
| B. | O₂ |
| C. | ATP |
| D. | Carbohydrate |
| Answer» D. Carbohydrate | |
| 16. |
The end products of noncyclic photophosphorylation are |
| A. | O₂, ATP and NADPH |
| B. | carbon dioxide, PGAL (phosphoglyceraldehyde), and H2 |
| C. | water, ADP and NADP+ |
| D. | carbon dioxide, ATP and water |
| Answer» B. carbon dioxide, PGAL (phosphoglyceraldehyde), and H2 | |
| 17. |
The effect of increased levels of hydrogen ions in the inter-membrane space of the mitochondria is |
| A. | Increase ATP production |
| B. | Decreased levels of oxidative phosphorylation |
| C. | Increased levels of water in inter-membrane space |
| D. | Decreased levels of chemiosmosis |
| Answer» B. Decreased levels of oxidative phosphorylation | |
| 18. |
Which of the following accepts only one electron? |
| A. | Cytochrome b |
| B. | Coenzyme Q |
| C. | FMN |
| D. | FAD |
| Answer» B. Coenzyme Q | |
| 19. |
NADP is a cofactor used in |
| A. | Catabolic reactions |
| B. | Anabolic reactions |
| C. | Elimination reaction |
| D. | Redox reactions |
| Answer» C. Elimination reaction | |
| 20. |
NADP⁺ in its reduced form is |
| A. | NAD |
| B. | NADH |
| C. | NADPH |
| D. | None of the mentioned |
| Answer» D. None of the mentioned | |
| 21. |
Which of the following is the prosthetic group of NADH dehydrogenase? |
| A. | NADH |
| B. | FAD |
| C. | NADPH |
| D. | FMN |
| Answer» E. | |
| 22. |
If rotenone is added to the mitochondrial electron transport chain |
| 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 |
| Answer» B. P: O ratio of NADH is reduced from 3:1 to 2:1 | |
| 23. |
The transport of acyl co-A for oxidation using a shuttle involves formation of the intermediate |
| A. | Acyl coenzyme A |
| B. | 3 acetyl co-A |
| C. | Acyl cartinine |
| D. | None of the mentioned |
| Answer» D. None of the mentioned | |
| 24. |
What do NAD+, NADP+, and FAD+ all have in common? |
| A. | They are reduced |
| B. | They have a full complement of electrons |
| C. | They are oxidized |
| D. | They are what is used during carbon fixation in photosynthesis |
| Answer» D. They are what is used during carbon fixation in photosynthesis | |
| 25. |
The proposal of chemiosmotic hypothesis was by |
| A. | Peter D. Mitchell |
| B. | Charles Darwin |
| C. | Mendele |
| D. | Alfred Russell |
| Answer» B. Charles Darwin | |
| 26. |
Complex 3 is also called _________ |
| A. | NADH dehydrogenase |
| B. | Succinate dehydrogenase |
| C. | Cytochrome bc1 complex |
| D. | Cytochrome oxidase |
| Answer» D. Cytochrome oxidase | |
| 27. |
The catabolism of sugars and fatty acids is similar because |
| A. | both of these compounds are funnelled through the TC A/citric acid cycle |
| B. | both of these compounds generate redox energy during catabolism |
| C. | both of these compounds generate chemical energy during catabolism |
| D. | all of the above |
| Answer» B. both of these compounds generate redox energy during catabolism | |
| 28. |
Where do the protons come from that make up the proton gradient used in the light reactions of photosynthesis? |
| A. | Glucose |
| B. | ATP |
| C. | H₂O |
| D. | NADPH |
| Answer» D. NADPH | |
| 29. |
A water-soluble protein that carries one electron present in chloroplast is |
| A. | PQʙ |
| B. | Q |
| C. | Cytochrome c |
| D. | Plastocyanin |
| Answer» E. | |
| 30. |
A mobile, lipid soluble carrier of two electrons present in chloroplasts is |
| A. | PQʙ |
| B. | Q |
| C. | Cytochrome c |
| D. | Plastocyanin |
| Answer» B. Q | |
| 31. |
One of the following is the source of electrons in photosynthesis |
| A. | Carbohydrates |
| B. | CO₂ |
| C. | Water |
| D. | NADH |
| Answer» D. NADH | |
| 32. |
Which of the following structures or processes are logically associated with chloroplasts? |
| A. | Plant cells |
| B. | Chlorophyll |
| C. | Thylakoid membranes |
| D. | All of these |
| Answer» E. | |
| 33. |
Hydrogen is transferred from the light reaction to the dark reaction in photosynthesis by |
| A. | DPN |
| B. | NAD |
| C. | ATP |
| D. | NADP |
| Answer» B. NAD | |
| 34. |
The size of plant mitochondrial DNA is |
| A. | 16kb |
| B. | 200-2500kb |
| C. | 100- 2550kb |
| D. | 100-2500kb |
| Answer» C. 100- 2550kb | |
| 35. |
Plastoquinol formed in PSII is oxidized by |
| A. | Cytochrome b₆f |
| B. | Cytochrome c |
| C. | Cytochrome f |
| D. | None of the mentioned |
| Answer» B. Cytochrome c | |
| 36. |
In algae, photosynthesis takes place in |
| A. | choloroplasts |
| B. | cell membrane |
| C. | mitochondria |
| D. | none of the above |
| Answer» B. cell membrane | |
| 37. |
Assume the combined processes of photosynthesis and cellular respiration, the electrons that start as part of H2O at the beginning of the light reactions end up attaching to |
| A. | O₂ to make new H₂O |
| B. | NADPH to make new glucose |
| C. | pyruvate to make ethanol |
| D. | electron transport carriers to make O₂ |
| Answer» B. NADPH to make new glucose | |
| 38. |
Every cycle of β-oxidation produces |
| A. | 1 FAD, 1 NAD⁺ and 2 CO₂ molecules |
| B. | 1 FADH₂, 1 NADH and 1 acetyl co-A |
| C. | 1 FADH₂, 1 NAD⁺ and 1 acetyl co-A |
| D. | 1 FAD, 1 NADH and 2 CO₂ molecules |
| Answer» C. 1 FADH₂, 1 NAD⁺ and 1 acetyl co-A | |
| 39. |
Which enzyme is involved in carbon-fixation reaction? |
| A. | NADP reductase |
| B. | Cytochrome reductase |
| C. | Ribulose bisphosphate carboxylase |
| D. | Glycerol kinase |
| Answer» D. Glycerol kinase | |
| 40. |
Calvin cycle occurs in |
| A. | Cytoplasm |
| B. | Chloroplast |
| C. | Mitochondria |
| D. | Golgi body |
| Answer» B. Chloroplast | |
| 41. |
Complex 2 is also called _________ |
| A. | NADH dehydrogenase |
| B. | Succinate dehydrogenase |
| C. | Cytochrome bc1 complex |
| D. | Cytochrome oxidase |
| Answer» C. Cytochrome bc1 complex | |
| 42. |
Energy that is released from glucose during respiration but not transferred to ATP bonds can be detected as |
| A. | CO₂ |
| B. | AMP |
| C. | ADP |
| D. | heat |
| Answer» E. | |
| 43. |
The size of human mitochondrial DNA is |
| A. | 16kb |
| B. | 200kb |
| C. | 2500kb |
| D. | 100kb |
| Answer» B. 200kb | |
| 44. |
A soluble Cu-containing electron transfer protein is |
| A. | Pheophytin |
| B. | Cytochrome c |
| C. | Plastocyanin |
| D. | Ferredoxin |
| Answer» D. Ferredoxin | |
| 45. |
During the light-dependent reactions of photosynthesis, which of the following does not occur? |
| A. | Splitting of water |
| B. | Carbon dioxide fixation |
| C. | Release of oxygen |
| D. | Absorption of light energy by photosystems |
| Answer» C. Release of oxygen | |
| 46. |
Complex 1 is also called _________ |
| A. | NADH dehydrogenase |
| B. | Succinate dehydrogenase |
| C. | Cytochrome bc1 complex |
| D. | Cytochrome oxidase |
| Answer» B. Succinate dehydrogenase | |
| 47. |
Cholesterol can be synthesized de novo in |
| A. | pancreas |
| B. | intestine |
| C. | liver |
| D. | cell membrane |
| Answer» D. cell membrane | |
| 48. |
Photosystem II is a |
| A. | Pheophytin-quinone type |
| B. | Ferredoxin type |
| C. | Plastocyanin type |
| D. | Plastocyanin-ferredoxin type |
| Answer» B. Ferredoxin type | |
| 49. |
Which one of the following is true about C₄ plants? |
| A. | They minimize rubisco oxygenase activity by fixing CO₂ into oxaloacetate |
| B. | They mainly occur in areas of high temperature and light intensity |
| C. | They minimize the rubisco oxygenase activity by fixing CO₂ into phosphoenolpyruvic acid |
| D. | C₃ plants are more efficient in photosynthesis than C₄ plants |
| Answer» B. They mainly occur in areas of high temperature and light intensity | |
| 50. |
When compared to retinal, chlorophyll can be described as a pigment that has a |
| A. | Narrow absorption range but high efficiency |
| B. | Narrow absorption range but low efficiency |
| C. | Wide absorption range but high efficiency |
| D. | Wide absorption range but low efficiency |
| Answer» B. Narrow absorption range but low efficiency | |