MCQOPTIONS
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MCQOPTIONS
This section includes 101 Mcqs, each offering curated multiple-choice questions to sharpen your Biochemistry knowledge and support exam preparation. Choose a topic below to get started.
| 51. |
How does Ras oncogene contribute to cancers? |
| A. | It codes for an anti-apoptotic protein, produced in abnormally large amounts |
| B. | It codes for a GTPase switch protein, which in its mutated form cannot be switched off |
| C. | It codes for a transcription factor produced abnormally in large amounts |
| D. | A growth factor that is continually active is encoded in its truncated form |
| Answer» C. It codes for a transcription factor produced abnormally in large amounts | |
| 52. |
Which of the following could be coded by a tumor-supressor gene? |
| A. | A protein that helps prevent progression through cell cycle |
| B. | A protein that helps prevent apoptosis |
| C. | A protein that codes for a DNA repair enzyme |
| D. | A protein that forms part of a growth factor signaling pathway |
| Answer» B. A protein that helps prevent apoptosis | |
| 53. |
Programmed cell death is termed as ___________ |
| A. | Metastasis |
| B. | Apoptosis |
| C. | Proliferation |
| D. | Mitotic termination |
| Answer» C. Proliferation | |
| 54. |
Acetylcholine receptor ion channel is an example of _____________ |
| A. | Gated ion channel |
| B. | Receptor enzymes |
| C. | Membrane protein |
| D. | Nuclear protein |
| Answer» B. Receptor enzymes | |
| 55. |
Insulin receptor is an example of _____________ |
| A. | Steroid receptors |
| B. | Serpentine receptors |
| C. | Adhesion receptors |
| D. | Receptor enzymes |
| Answer» E. | |
| 56. |
Receptor proteins that indirectly activate enzymes that generate intracellular second messengers are _____________ |
| A. | Steroid receptors |
| B. | Serpentine receptors |
| C. | Adhesion receptors |
| D. | Receptor enzymes |
| Answer» C. Adhesion receptors | |
| 57. |
Which of the following is a nuclear receptor protein? |
| A. | Steroid receptor |
| B. | Adhesion receptor |
| C. | Serpentine receptor |
| D. | Receptor with no intrinsic enzyme activity |
| Answer» B. Adhesion receptor | |
| 58. |
How many types of signal transducers are there? |
| A. | 3 |
| B. | 4 |
| C. | 5 |
| D. | 6 |
| Answer» E. | |
| 59. |
Protein kinase ERK is activated by phosphorylation of ____________ |
| A. | Only Thr |
| B. | Only Tyr |
| C. | Both Thr and Tyr |
| D. | Only Ser |
| Answer» D. Only Ser | |
| 60. |
Which of the following about Rb tumor suppressor protein is correct? |
| A. | It binds E2F transcription factor and prevents cell from entering S phase until a mitogenic signal is received |
| B. | It is activated when phosphorylated by Cdk |
| C. | It is a transcription factor |
| D. | When a mitogenic signal is received, it binds the transcription factor E2F and thus stimulates the cell to enter S phase |
| Answer» B. It is activated when phosphorylated by Cdk | |
| 61. |
Depolarization and repolarization changes that occur during the action potential are produced by ____________ |
| A. | Negative feedback loops |
| B. | Carrier mediated transport |
| C. | Simple diffusion of ions down their concentration gradient |
| D. | Active transport pumps along the neuron membrane |
| Answer» E. | |
| 62. |
cGMP-dependent protein kinase is also called ____________ |
| A. | Protein kinase B |
| B. | Protein kinase A |
| C. | Protein kinase G |
| D. | Protein kinase C |
| Answer» D. Protein kinase C | |
| 63. |
Which of the following statements is true about transmembrane electrical potential? |
| A. | The chemical gradient drives Cl⁻ and K⁺ inwards |
| B. | The electrical gradient drives Na⁺ and Ca⁺² inwards |
| C. | The chemical gradient drives Na⁺ and Ca⁺² inwards and K⁺ outward |
| D. | The chemical gradient drives Cl⁻ and K⁺ outwards |
| Answer» D. The chemical gradient drives Cl⁻ and K⁺ outwards | |
| 64. |
In which phase of cell cycle is DNA replicated? |
| A. | G₁ phase |
| B. | S phase |
| C. | G₂ phase |
| D. | M phase |
| Answer» C. G₂ phase | |
| 65. |
A factor involved in regulating the fate of stem cells in plant development is _________ |
| A. | Adrenaline |
| B. | Epinephrine |
| C. | Thyroid stimulating hormone |
| D. | CLV1 |
| Answer» E. | |
| 66. |
Cholera toxin is not a/an _________ |
| A. | Enzyme inhibitor |
| B. | Enzyme activator |
| C. | Enzyme modifier |
| D. | Toxin released from bacteria in the infected intestine |
| Answer» C. Enzyme modifier | |
| 67. |
Which of the following statements regarding cyclins is not correct? |
| A. | They can become linked to ubiquitin |
| B. | They catalyze the phosphorylation of protein |
| C. | They contain a specific amino acid sequence that target them for proteolysis |
| D. | They are activated and degraded during cell cycle |
| Answer» E. | |
| 68. |
Which of the following is not a downstream component? |
| A. | Ras |
| B. | MEK |
| C. | ERK |
| D. | PIP3 |
| Answer» E. | |
| 69. |
Which of the following is not responsible of producing diarrhea? |
| A. | Elevation in [cGMP] |
| B. | Increase in Cl⁻ secretion |
| C. | Decrease in reabsorption of water by the intestinal epithelium |
| D. | Decrease in Cl⁻ secretion |
| Answer» E. | |
| 70. |
The specificity of signaling pathways does not include ___________ |
| A. | Migration of signal proteins into membrane rafts |
| B. | Assembly of large multiprotein complexes |
| C. | Phosphorylation of target proteins at Ser, Thr/Tyr residues |
| D. | Flippase-catalyzed movement of phospholipids from the inner to the outer leaflet |
| Answer» E. | |
| 71. |
What is the drug antagonist of estrogen? |
| A. | Tanoxifen |
| B. | Metformin |
| C. | Glucophage |
| D. | Victoza |
| Answer» B. Metformin | |
| 72. |
Plasma membrane protein predicted to have seen 7 transmembrane helices segment binds __________ |
| A. | Progesterone |
| B. | Thyroid stimulating hormone |
| C. | Insulin |
| D. | Follicle stimulating hormone |
| Answer» B. Thyroid stimulating hormone | |
| 73. |
Receptor is removed from cell surface in _____________ |
| A. | Specificity |
| B. | Amplification |
| C. | Adaptation |
| D. | Integration |
| Answer» D. Integration | |
| 74. |
Number of affected molecules increases geometrically in an enzyme cascade in _____________ |
| A. | Specificity |
| B. | Amplification |
| C. | Adaptation |
| D. | Integration |
| Answer» C. Adaptation | |
| 75. |
Signal molecule fits the binding site on its complementary receptor called as _____________ |
| A. | Specificity |
| B. | Amplification |
| C. | Integration |
| D. | Cooperativity |
| Answer» B. Amplification | |
| 76. |
The information which is represented by a signal is detected by specific receptors and converted to a cellular response; this conversion is called _____________ |
| A. | Signal amplification |
| B. | Signal transversion |
| C. | Signal transduction |
| D. | Signal integration |
| Answer» D. Signal integration | |
| 77. |
Activation of guanylyl cyclase produces ____________ |
| A. | Guanosine 3’, 5’-cyclic monophosphate |
| B. | Guanosine 2’, 5’-cyclic monophosphate |
| C. | Guanosine 4’, 5’-cyclic monophosphate |
| D. | Guanosine 1’, 5’-cyclic monophosphate |
| Answer» B. Guanosine 2’, 5’-cyclic monophosphate | |
| 78. |
Regulatory outcome results from integrated input from both receptors is in _____________ |
| A. | Specificity |
| B. | Amplification |
| C. | Adaptation |
| D. | Integration |
| Answer» E. | |
| 79. |
Voltage regulation means ____________ |
| A. | Na⁺/K⁺ pumps controls potential |
| B. | Unless the voltage is regular gates will not respond |
| C. | Oscilloscope only can control potential |
| D. | With changes in the membrane potential voltage gated ion channels open and close |
| Answer» E. | |
| 80. |
Which property of p53 enables it to prevent the development of cancer? |
| A. | It is a transcription factor that causes protein production which stimulates the cell cycle |
| B. | It prevents replication of cells with damaged DNA |
| C. | It prevents cells from triggering apoptosis |
| D. | It stimulates synthesis of DNA repair enzymes that replace telomere sequence lost during cell division |
| Answer» C. It prevents cells from triggering apoptosis | |
| 81. |
Which drug is used to terminate early pregnancies? |
| A. | RU486 |
| B. | Metformin |
| C. | Glucophage |
| D. | Victoza |
| Answer» B. Metformin | |
| 82. |
Scaffold protein in insulin signal transduction ___________ |
| A. | KSR |
| B. | IRS-1 |
| C. | MEKK1 |
| D. | AKAP |
| Answer» C. MEKK1 | |
| 83. |
SH₂ domain specifically binds to _____________ |
| A. | GDP |
| B. | Ca⁺² |
| C. | Phosphorylated tyrosine residues |
| D. | Phosphorylated serine residues |
| Answer» D. Phosphorylated serine residues | |
| 84. |
Nicotinic acetylcholine receptor is an example of _____________ |
| A. | Ligated gated receptor channel |
| B. | Serpentine receptors |
| C. | Adhesion receptors |
| D. | Receptor enzymes |
| Answer» B. Serpentine receptors | |
| 85. |
At the end of each phase of cell cycle cyclins activating Cdks in that phase are inactivated irreversibly by _____________ |
| A. | Multiple phosphorylations |
| B. | De-phosphorylation |
| C. | Ubiquitinylation |
| D. | Destabilizing by proteolysis in a proteosome |
| Answer» E. | |
| 86. |
Which out of the following is not involved in signal transduction by β-adrenergic receptor pathway? |
| A. | GTP |
| B. | ATP |
| C. | cAMP |
| D. | cGMP |
| Answer» D. cGMP | |
| 87. |
Autophosphorylation is done on _________ |
| A. | His residues |
| B. | Ser/Thr residues |
| C. | Cys residues |
| D. | Lys residues |
| Answer» C. Cys residues | |
| 88. |
Diffusion of K⁺ out of the cell makes the inside of it less positive, or more negative and acts to restore the original resting membrane potential. This process is called ____________ |
| A. | Repolarization |
| B. | Depolarization |
| C. | Hyperpolarization |
| D. | Overshoot |
| Answer» B. Depolarization | |
| 89. |
Oncogenes do not encode for ___________ |
| A. | Trans-membrane protein receptors |
| B. | Growth factors |
| C. | DNA-dependent RNA polymerase |
| D. | Cytoplasmic G-proteins and protein kinases |
| Answer» D. Cytoplasmic G-proteins and protein kinases | |
| 90. |
Which of the following statements about Arabidopsis is not true? |
| A. | In Arabidopsis, CTR-1 Ser/Thr protein kinase is activated by ethylene |
| B. | Activation of MAPK cascade |
| C. | EINI activation |
| D. | Synthesis of ERF1 transcription factor |
| Answer» B. Activation of MAPK cascade | |
| 91. |
Which out of the following statements is true about G-protein couple receptors? |
| A. | The N-terminal chain is extracellular and C-terminal chain is intracellular |
| B. | It contains 5 trans-membrane hydrophobic sections |
| C. | There are more extracellular loops than intracellular loops |
| D. | The binding region for G-protein involves 2 extracellular loops |
| Answer» B. It contains 5 trans-membrane hydrophobic sections | |
| 92. |
The 2-component system drives bacterial chemotaxis by coupling autophosphoryaltion of which receptor to phosphorylation of respective regulatory protein? |
| A. | His kinase |
| B. | Adenylyl cyclase |
| C. | Guanylyl cyclase |
| D. | None of the mentioned |
| Answer» B. Adenylyl cyclase | |
| 93. |
What is Ubiquitin? |
| A. | Protein kinase |
| B. | Protease |
| C. | Component of the electron transport system |
| D. | Protein that tags another protein for proteolysis |
| Answer» E. | |
| 94. |
When visual stimulus reaches receptors in retina of eye, second process involving absorption of physical energy by receptors is? |
| A. | Reception |
| B. | Transduction |
| C. | Coding |
| D. | Adaptation |
| Answer» C. Coding | |
| 95. |
Proto-oncogenes can be transformed to oncogenes by all of the following mechanisms except _____________ |
| A. | Elimination of their start signals for translation |
| B. | During a viral infection cycle |
| C. | Chromosomal rearrangements |
| D. | Chemically induced mutagenesis |
| Answer» B. During a viral infection cycle | |
| 96. |
Migration of cancerous cells from the site of origin to other part of the body forming secondary tumors is called ___________ |
| A. | Diapedesis |
| B. | Metastasis |
| C. | Proliferation |
| D. | Apoptosis |
| Answer» C. Proliferation | |
| 97. |
Steroid regulatory proteins mediate the act by binding at ___________ |
| A. | Zinc finger motif |
| B. | Leucine zipper motif |
| C. | Helix turn helix motif |
| D. | Histone helix motif |
| Answer» B. Leucine zipper motif | |
| 98. |
Which is an example of negative regulator? |
| A. | CAP |
| B. | Lac 1 gene |
| C. | Nuclear receptors |
| D. | Phosphorylated STAT proteins |
| Answer» C. Nuclear receptors | |
| 99. |
Which out of the following statements is true about gene regulation in bacteria? |
| A. | Repressor protein blocks transcription by binding to operator sequence |
| B. | Activator proteins bind near promoters and increase the efficiency of transcription |
| C. | Enhancers commonly regulate transcription |
| D. | Genes with related functions are often grouped together and have a single start codon |
| Answer» B. Activator proteins bind near promoters and increase the efficiency of transcription | |
| 100. |
Which is an example of a positive regulator? |
| A. | CAP |
| B. | Lac 1 gene |
| C. | Trp operon |
| D. | Met operon |
| Answer» B. Lac 1 gene | |