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.
| 51. |
The first intermediate in TCA cycle is |
| A. | succinate |
| B. | fumerate |
| C. | citrate |
| D. | malate |
| Answer» D. malate | |
| 52. |
What is the rate of apoptosis in average human adult per day? |
| A. | 10 billion cells |
| B. | 30 billion cells |
| C. | 50-70 billion cells |
| D. | 100 billion cells |
| Answer» D. 100 billion cells | |
| 53. |
Electron transport systems play a vital role in |
| A. | Calvin cycle |
| B. | photorespiration |
| C. | light-dependent reactions |
| D. | all of these |
| Answer» D. all of these | |
| 54. |
What is the maximum absorption wavelength for photosystem I in green plants? |
| A. | 550 nm |
| B. | 600 nm |
| C. | 700 nm |
| D. | 750 nm |
| Answer» D. 750 nm | |
| 55. |
In cells having organelles, the steps of the Krebs cycle and the electron transport system occur in the |
| A. | cell membrane |
| B. | mitochondria |
| C. | endoplasmic reticulum |
| D. | none of these |
| Answer» C. endoplasmic reticulum | |
| 56. |
How many human mitochondrial proteins are encoded in the mitochondrial genome and synthesized within mitochondria? |
| A. | 11 |
| B. | 12 |
| C. | 13 |
| D. | 14 |
| Answer» D. 14 | |
| 57. |
The rate of photorespiration in most plants increases at.higher temperatures. Some plants have evolved a somewhat round-about system to deal with this problem. This series of reactions is called |
| A. | ETS (electron transfer system in light reactions |
| B. | C4 pathway |
| C. | Photosystem II |
| D. | Calvin cycle |
| Answer» C. Photosystem II | |
| 58. |
Antenna complexes, electron transport chains, and carbon fixation are all found in |
| A. | animal cells |
| B. | bacterial cells |
| C. | plant cells |
| D. | association with the reactions of the citric acid cycle |
| Answer» D. association with the reactions of the citric acid cycle | |
| 59. |
The first person to study the influence of light during photosynthesis is |
| A. | Blackmann |
| B. | Van Niel |
| C. | J. Ingenhouz |
| D. | Warburg |
| Answer» D. Warburg | |
| 60. |
Which of the following represents a correct ordering of the events that occur during the respiration of glucose in the absence of O₂? |
| A. | Glycolysis; citric acid cycle; oxidative phosphorylation |
| B. | Glycolysis; oxidative phosphorylation; citric acid cycle |
| C. | Oxidative phosphorylation; citric acid cycle; glycolysis |
| D. | Glycolysis; fermentation |
| Answer» E. | |
| 61. |
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 |
| D. | Zero |
| Answer» B. One more than normally produced by succinate | |
| 62. |
In noncyclic photophosphorylation, the ultimate acceptor of electrons that have been produced from the splitting of water is |
| A. | NADP+ |
| B. | chlorophyll a |
| C. | carbon dioxide |
| D. | chlorophyll b |
| Answer» D. chlorophyll b | |
| 63. |
As a result of the photosynthetic process, which product is formed? |
| A. | Oxygen |
| B. | Water |
| C. | Carbon dioxide |
| D. | Both (a) and (b) |
| Answer» B. Water | |
| 64. |
NADP-linked dehydrogenase catalyzes _________ |
| A. | Glucose 6-phosphate+NADP⁺ ↔ 6-phosphogluconate + NADPH + H⁺ |
| B. | Lactate + NAD⁺ ↔ pyruvate + NADH + H⁺ |
| C. | Pyruvate + CoA + NAD⁺ ↔ acetyl-CoA + CO₂ + NADH + H⁺ |
| D. | L-Malate + NAD⁺ ↔ oxaloacetate + NADH + H⁺ |
| Answer» B. Lactate + NAD⁺ ↔ pyruvate + NADH + H⁺ | |
| 65. |
The measure of potential energy stored as combination of proton and voltage gradients across membrane is termed as |
| A. | Proton motive force |
| B. | Electron motive force |
| C. | Molecule motive force |
| D. | Ion motive force |
| Answer» B. Electron motive force | |
| 66. |
Where does oxidative phosphorylation take place? |
| A. | Ribosomes |
| B. | Nucleus |
| C. | Mitochondria |
| D. | Cell membrane |
| Answer» D. Cell membrane | |
| 67. |
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 |
| Answer» D. Decreased production of heat | |
| 68. |
The first stable product of dark reaction in C₄ plants is |
| A. | Phosphoglyceric acid |
| B. | Oxaloacetic acid |
| C. | Glycolic acid |
| D. | Malic acid |
| Answer» B. Oxaloacetic acid | |
| 69. |
Cyanobacteria does not use which of the following for both oxidative and photophosphorylation? |
| A. | Cytochrome c₆ |
| B. | Cytochrome b₆f |
| C. | Plastoquinone |
| D. | Plastocyanin |
| Answer» E. | |
| 70. |
The acyl co-A formed in the cytosol is transported to |
| A. | Mitochondrial matrix |
| B. | Microsomes |
| C. | ER |
| D. | Remains in cytosol |
| Answer» B. Microsomes | |
| 71. |
Malate-asparatate shuttle operates in |
| A. | lungs and liver |
| B. | heart and liver |
| C. | pancreas and liver |
| D. | none of these |
| Answer» C. pancreas and liver | |
| 72. |
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 |
| Answer» B. Electron flow will continue but ATP synthesis will be increased | |
| 73. |
Why is the TCA cycle the central pathway of metabolism of the cell? |
| A. | It occurs in the center of the cell |
| B. | Its intermediates are commonly used by other metabolic reactions |
| C. | All other metabolic pathways depend upon it |
| D. | None of the above |
| Answer» C. All other metabolic pathways depend upon it | |
| 74. |
Why light is required for light dependent reactions? |
| A. | It splits ATP molecules which generates the energy necessary to power the light independent reactions |
| B. | It is the source for electrons |
| C. | It splits the water molecules |
| D. | It energizes electrons in the reaction center |
| Answer» E. | |
| 75. |
Membrane potential and proton gradient |
| A. | Cancel one another when uncouplers are present |
| B. | Reinforce one another when respiratory inhibitors are present |
| C. | Are sufficient, separately to make ATP from ADP + Pi |
| D. | Are required to make ATP |
| Answer» E. | |
| 76. |
Mitochondrial DNA is one of the best marker tools for population biologists and evolutionary biologists because |
| A. | Absence of genetic recombination in mt-DNA |
| B. | Mitochondrial genes are specific to mt-DNA |
| C. | It can be easily isolated |
| D. | It undergoes spontaneous mutation |
| Answer» B. Mitochondrial genes are specific to mt-DNA | |
| 77. |
More ATP is manufactured during __________ than at any other time in all of cellular metabolism. |
| A. | fermentation |
| B. | glycolysis |
| C. | the light reactions of photosynthesis |
| D. | oxidative phosphorylation |
| Answer» E. | |
| 78. |
Glycolysis takes places in the __________ and produces __________ , which in the presence of oxygen then enters the __________ . |
| A. | cytosol; glucose; mitochondrion to complete fermentation |
| B. | cytosol; pyruvate; mitochondrion to complete fermentation |
| C. | cytosol; pyruvate; mitochondrion to complete cellular respiration |
| D. | mitochondrion; pyruvate; chloroplast to complete photosynthesis |
| Answer» D. mitochondrion; pyruvate; chloroplast to complete photosynthesis | |
| 79. |
Which of the following statements about energy metabolism is false? |
| A. | The energy that powers living systems ultimately comes from the sun |
| B. | All animals in some way rely on plants for their energy |
| C. | Plants provide the water and CO₂ that animals need to carry out respiration |
| D. | All eukaryotic organisms carry out respiration in the presence of O₂ |
| Answer» D. All eukaryotic organisms carry out respiration in the presence of O₂ | |
| 80. |
The vast majority of the molecules that act as energy carriers to power cellular activities are made in |
| A. | the nucleus |
| B. | the Golgi apparatus |
| C. | the cytosol |
| D. | the mitochondria and chloroplasts |
| Answer» E. | |
| 81. |
Hydrogen (electron) acceptor in the light reactions is |
| A. | ADP |
| B. | NADP+ |
| C. | NAD+ |
| D. | FADH |
| Answer» C. NAD+ | |
| 82. |
Light energy is converted to chemical energy in the presence of |
| A. | Chloroplast |
| B. | Ribosomes |
| C. | Mitochondria |
| D. | Stomata |
| Answer» B. Ribosomes | |
| 83. |
Protein that contains a nucleic acid derivative of riboflavin is called _________ |
| A. | Nucleic acid |
| B. | Amino acid |
| C. | Flavoprotein |
| D. | None of the mentioned |
| Answer» D. None of the mentioned | |
| 84. |
NADP+ is reduced to NADPH during |
| A. | light dependent reactions |
| B. | photorespiration |
| C. | calvin cylcle |
| D. | none of these |
| Answer» B. photorespiration | |
| 85. |
Programmed cell death can be termed as |
| A. | Oxidative stress |
| B. | Apoptosis |
| C. | Cell division |
| D. | Cell cycle |
| Answer» C. Cell division | |
| 86. |
Favorable conditions for cyclic photophosphorylation are |
| A. | Aerobic and optimum light |
| B. | Aerobic condition only |
| C. | Aerobic and low light intensity |
| D. | Anaerobic and low light intensity |
| Answer» B. Aerobic condition only | |
| 87. |
In the Calvin cycle, carbon dioxide is fixed in a reaction with the |
| A. | ribulose diphosphate |
| B. | ribulose phosphate |
| C. | ribose tri phosphate |
| D. | 3-phosphoglyceric acid |
| Answer» B. ribulose phosphate | |
| 88. |
Products of glucose oxidation essential for oxidative phosphorylation are |
| A. | Pyruvate |
| B. | Acetyl co-A |
| C. | NADPH and ATP |
| D. | NADH and FADH₂ |
| Answer» E. | |
| 89. |
Which of the following statements about thylakoids is false? |
| A. | They contain chlorophyll pigments |
| B. | They contain the photosystems |
| C. | They contain Calvin cycle enzymes |
| D. | They contain the electron transport machinery |
| Answer» D. They contain the electron transport machinery | |
| 90. |
The first step in the β oxidation of fatty acyl co-A is catalyzed by _________ |
| A. | Succinate dehydrogenase |
| B. | NADH dehydrogenase |
| C. | ATP synthase |
| D. | Acyl co-A dehydrogenase |
| Answer» E. | |
| 91. |
The percentage of light energy fixed in photosynthesis is around |
| A. | 100% |
| B. | 10% |
| C. | 1% |
| D. | 0.1% |
| Answer» D. 0.1% | |
| 92. |
Which of the following enzyme does not take part in the TCA cycle? |
| A. | Citrate synthase |
| B. | Iso-citrate dehydrogenase |
| C. | Pyruvate dehydrogenase |
| D. | Malate dehydrogenase |
| Answer» D. Malate dehydrogenase | |
| 93. |
Which of the following is involved in energy production? |
| A. | Generation of proton gradients across membranes |
| B. | Transport of electrons on organic molecules |
| C. | Conversion of compounds with high energy to those of low energy |
| D. | All of the above |
| Answer» E. | |
| 94. |
What do coenzyme A, CO₂, oxaloacetate, and FADH₂ all have in common? |
| A. | They are all components or products of the citric acid cycle |
| B. | They are part of the dark reactions of photosynthesis |
| C. | They are part of the reactions of lactic acid fermentation |
| D. | They are all elements of oxidative phosphorylation |
| Answer» B. They are part of the dark reactions of photosynthesis | |
| 95. |
Complex 4 is also called _________ |
| A. | NADH dehydrogenase |
| B. | Succinate dehydrogenase |
| C. | Cytochrome bc1 complex |
| D. | Cytochrome oxidase |
| Answer» E. | |
| 96. |
A cyclic electron transport process is the characteristic of |
| A. | photosynthesis |
| B. | methane oxidation |
| C. | sulfide oxidation |
| D. | methane production |
| Answer» B. methane oxidation | |
| 97. |
Which of the following about Calvin cycle is correct? |
| A. | It is a metabolic pathway by which plants convert CO₂ into pentose sugars as the main product |
| B. | With decrease in light intensity, the enzymes are more reactive |
| C. | Rubisco adds CO₂ to 3-phosphoglycerate |
| D. | It is a metabolic pathway by which plants convert CO₂ and water into carbohydrates |
| Answer» E. | |
| 98. |
Rubisco (RuBP Carboxylase-oxygenase enzyme), glyceraldehyde 3-phosphate, and NADPH all play a role in |
| A. | the dark reactions of photosynthesis |
| B. | the breakdown of glucose into CO₂ |
| C. | cellular respiration when O₂ is present |
| D. | alcohol fermentation |
| Answer» B. the breakdown of glucose into CO₂ | |
| 99. |
Carbon fixation requires the expenditure of ATP molecules which is generated by |
| A. | formation of glucose during the Calvin cycle |
| B. | replenishment of chlorophyll |
| C. | ETS (electron transfer system) during the light reactions |
| D. | none of the above |
| Answer» D. none of the above | |
| 100. |
More than what proportion of mitochondrial proteins are coded by nuclear DNA? |
| A. | 95% |
| B. | 50% |
| C. | 10% |
| D. | 40% |
| Answer» B. 50% | |