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Multiple choice question for engineering

Set 1

1. Which of the following statements regarding cyclin-dependent protein kinase is not correct?
a) Their activity is regulated by cyclins
b) They can alter the activity of proteins involve in the progression of cells through cell cycle
c) Their activity fluctuates during cell cycle
d) Each type of cell contains one specific form
e) Their activity is regulated by changes in gene expression, protein phosphorylation and proteolysis

View Answer

Answer: c [Reason:] They remain constant throughout cell cycle.

2. 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 specific amino acid sequence that target them for proteolysis
d) They are activated and degraded during cell cycle

View Answer

Answer: d [Reason:] They activate cdk enzymes.

3. Ubiquitin is a
a) Protein kinase
b) Protease
c) Component of the electron transport system
d) Protein that tags another protein for proteolysis

View Answer

Answer: d [Reason:] Ubiquitin binds to a substrate protein resulting in their degradation.

4. Cdk2/cyclinE functions in
a) G2/M transition
b) G2
c) M
d) G1/S transition

View Answer

Answer: d [Reason:] Cdk1/cyclinB functions in M phase Cdk2/cyclinA functions in S phase, G2 phase.

5. In which phase of cell cycle is DNA replicated?
a) G1 phase
b) S phase
c) G2 phase
d) M phase

View Answer

Answer: b [Reason:] During S phase, DNA replication takes place.

6. Cyclin dependent kinases which control progression through cell cycle checkpoints are totally activated by which of the following
a) Binding to cyclin, plus phosphorylation by a Cdk activating protein kinase
b) Binding to cyclins
c) Phosphorylation by Cdk activating protein kinase
d) Phosphorylation by a tyrosine kinase

View Answer

Answer: a [Reason:] Cyclin dependent kinases are totally activated by binding to cyclin and phosphorylation by a Cdk activating protein kinase.

7. 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

View Answer

Answer: d [Reason:] At the end of each phase of cell cycle, cyclins are inactivated irreversibly by destabilizing by proteolysis in a proteasome.

8. At which cell cycle checkpoint, cell cycle is halted if cell’s DNA is damaged
a) G1 – S
b) S – G2
c) G2 – M
d) G0 – G1

View Answer

Answer: a [Reason:] During G1 phase cell grows and during S phase DNA replicates. So there must be a checkpoint between these two phases to check if there is a damage in DNA.

9. Which of the following occurs in meiosis but not in mitosis?
a) Attachment of spindle fibers to kinetochore
b) Replication of DNA prior to start of cell division
c) Separation of sister chromatids at anaphase
d) Pairing of homologous chromosomes at metaphase plate

View Answer

Answer: d [Reason:] Pairing of homologous chromosomes at metaphase plate does not occur in mitosis.

10. Passage of a cell through stages of cell cycle is controlled by a protein kinase that phosphorylates many different proteins at appropriate times
a) Cdk activating kinase
b) Cyclin-dependent kinase
c) Cyclins
d) Tyrosine kinase

View Answer

Answer: b [Reason:] Passage of a cell through stages of cell cycle is controlled by Cdk.

Set 2

1. Which out of the following statements is true about regulation of metabolic pathway?
a) Most of the metabolic pathways are regulated
b) Most of the metabolic pathways are not regulated
c) Regulation of metabolic pathways always involves changing the amount of enzymes
d) Metabolic regulation always depends on control by hormones

View Answer

Answer: a [Reason:] According to the physiological needs, rate of metabolism needs to be changed.

2. The rate of breakdown of metabolites is termed as
a) Metabolic state
b) Metabolism
c) Steady state
d) Homeostasis

View Answer

Answer: c [Reason:] The rate of breakdown of metabolites is termed as steady state.

3. Diminished delivery of oxygen to tissues is termed as
a) Hypoxia
b) Ischemia
c) Homeostasis
d) Metabolism

View Answer

Answer: a [Reason:] Diminished delivery of oxygen to tissues is termed as hypoxia.

4. Diminished flow of blood to tissues is termed as
a) Hypoxia
b) Ischemia
c) Homeostasis
d) Metabolism

View Answer

Answer: b [Reason:] Diminished flow of blood to tissues is termed as ischemia.

5. Which of the following statements is true about the control of muscle glycogen phosphorylase?
a) It is activated by phosphorylation by an active phosphorylase kinase
b) It is allosterically activated by ATP
c) It is allosterically activated by cAMP
d) Normally it exists in active form

View Answer

Answer: a [Reason:] It is allosterically inhibited by ATP. It is partially activated allosterically by AMP. Normally it exists in inactive form.

6. Which of the following is not a factor determining the activity of an enzyme?
a) Association with regulatory protein
b) Sequestration
c) Allosteric regulation
d) Nucleotides

View Answer

Answer: d [Reason:] Association with regulatory protein, sequestration, allosteric regulation and covalent modification are the factors determining the activity of an enzyme.

7. Which of the following statements is true?
a) High insulin/glucagon ratio activates lipolysis in muscle
b) High insulin/glucagon ratio inhibits lipolysis in liver
c) High insulin/glucagon ratio activates lipolysis in adipocytes
d) Low insulin/glucagon ratio activates lipolysis in adipocytes

View Answer

Answer: d [Reason:] A high insulin/glucagon inactivates lipolysis.

8. Which of the following type of metabolite is used for generating glucose under severe starvation conditions?
a) Amino acids
b) Fats
c) Glycogen
d) Starch

View Answer

Answer: a [Reason:] Fats cannot be converted to glucose; there is no store of carbohydrate. Only amino acids can be used for generating glucose under severe starvation conditions.

9. Which of the following statements is true about brain metabolism in starvation?
a) The brain can use glucogenic amino acids for energy
b) The brain can only use glucose as fuel
c) Up to a quarter of energy requirement of the brain can come from fatty acids
d) Up to a half of energy requirement of the brain can come from ketone bodies

View Answer

Answer: a [Reason:] Brain does not use amino acids directly but glucose derived from glucogenic amino acids in the liver.

10. One of the following statements about the control of enzyme activity by phosphorylation is correct
a) Phosphorylation of an enzyme results in conformational change
b) Phosphorylation of an enzyme occurs only at specific tyrosine residues
c) Phosphorylation of an enzyme is carried out by phosphoprotein phosphatases
d) Enzyme control by phosphorylation is irreversible

View Answer

Answer: a [Reason:] Phosphorylation of enzyme is reversible; phosphorylation is not carried out by phosphoprotein phosphatases.

Set 3

1. 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

View Answer

Answer: c [Reason:] The regulation of oxidative phosphorylation depends on magnitude of proton motive force.

2. The rate of electron transfer when proton motive force is high is
a) Faster
b) Slower
c) Moderate
d) None

View Answer

Answer: b [Reason:] When proton motive force is high, rate of electron transfer is slower.

3. The magnitude of proton motive force depends on
a) Energy charge of cell
b) Permeability of membrane
c) Number of ribosomes in cell
d) None

View Answer

Answer: a [Reason:] The magnitude of proton motive force depends on energy charge of cell.

4. Where does oxidative phosphorylation take place?
a) Ribosomes
b) Nucleus
c) Mitochondria
d) Cell membrane

View Answer

Answer: c [Reason:] Oxidative phosphorylation takes place in mitochondria.

5. In metabolism, NAD is involved in
a) Spontaneous reaction
b) Elimination reaction
c) Redox reactions
d) None

View Answer

Answer: c [Reason:] NAD is involved in redox reactions.

6. NADP is a cofactor used in
a) Catabolic reactions
b) Anabolic reactions
c) Elimination reaction
d) Redox reactions

View Answer

Answer: b [Reason:] NADP is a cofactor used in anabolic reactions.

7. What is the proportion of ATP produced by oxidative phosphorylation?
a) 60%
b) 70%
c) 80%
d) 90%

View Answer

Answer: a [Reason:] About 60% of ATP produced by oxidative phosphorylation.

8. NADP+ in its reduced form is
a) NAD
b) NADH
c) NADPH
d) None

View Answer

Answer: c [Reason:] NADPH is the reduced form of NADP+.

9. Products of glucose oxidation essential for oxidative phosphorylation are
a) Pyruvate
b) Acetyl co-A
c) NADPH and ATP
d) NADH and FADH2

View Answer

Answer: d [Reason:] The end products of Krebs cycle are CO2, NADH, FADH2, ATP and water. The reactants of oxidative phosphorylation are NADH, FADH2, O2, ADP and P.

10. 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

View Answer

Answer: a [Reason:] There is an increased ATP production, if the levels of hydrogen ions increase in the inter-membrane space of the mitochondria.

Set 4

1. How do steroid hormones produce their effects in cells?
a) By activating key enzymes in metabolic pathway
b) By binding to intracellular receptors and promoting transcription of specific genes
c) By promoting degradation of specific m-RNAs
d) By activating translation of certain m-RNAs

View Answer

Answer: b [Reason:] Steroid hormones produce their effects in cells by binding to intracellular receptors and promoting transcription of specific genes.

2. An example of positive regulator
a) CAP
b) Lac 1 gene
c) Trp operon
d) Met operon

View Answer

Answer: a [Reason:] Lac 1 gene, Trp operon and Met operon are negative regulators.

3. An example of negative regulator
a) CAP
b) Lac 1 gene
c) Nuclear receptors
d) Phosphorylated STAT proteins

View Answer

Answer: b [Reason:] CAP, Nuclear receptors and Phosphorylated STAT proteins are positive regulators.

4. 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

View Answer

Answer: a [Reason:] Steroid regulatory proteins mediate the act by binding at zinc finger motif.

5. 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

View Answer

Answer: a [Reason:] A repressor binds at operator element and regulates transcription negatively.

6. Steroid hormones receptor binds to
a) Hormone response elements in m-RNA
b) Hormone response elements in DNA
c) Hormone response elements in proteins
d) Ribosomes to stimulate translation
e) Cell membrane thereby increases permeability

View Answer

Answer: b [Reason:] Hormone response elements are short sequence of DNA where steroid hormone receptors bind.

7. Mode of action of steroid hormones involve
a) Stimulation of DNA replication
b) Stimulation of m-RNA transcription
c) Inhibition of protein synthesis
d) Secondary messenger

View Answer

Answer: b [Reason:] Steroid hormones involve in the stimulation of m-RNA transcription, affecting the gene expression.

8. The drug antagonist of estrogen is
a) Tanoxifen
b) Metformin
c) Glucophage
d) Victoza

View Answer

Answer: a [Reason:] Tanoxifen is an antagonist of estrogen.

9. The drug used to terminate early pregnancies is
a) RU486
b) Metformin
c) Glucophage
d) Victoza

View Answer

Answer: a [Reason:] Metformin, Glucophage and victoza are the drugs to cure diabetes.

10. Plasma membrane protein predicted to have seen 7 transmembrane helices segment binds
a) Progesterone
b) Thyroid stimulating hormone
c) Insulin
d) Follicle stimulating hormone

View Answer

Answer: a [Reason:] Progesterone hormone is a steroid hormone, can diffuse through cell membranes.

Set 5

1. The allosteric inhibitor of an enzyme
a) Causes the enzyme to work faster
b) Binds to the active site
c) Participates in feedback regulation
d) Denatures the enzyme

View Answer

Answer: c [Reason:] In feedback regulation, enzyme is not directly inhibited by the end product instead its synthesis is inhibited by interfering with the gene of that enzyme.

2. Which of the following is false about allosteric feedback inhibition?
a) Bacterial enzyme system is the first known example
b) Conversion of L-leucine to L-isoleucine
c) Threonine dehydratase is inhibited by isoleucine
d) If the isoleucine concentration decreases, the rate of threonine dehydration increases

View Answer

Answer: b [Reason:] The bacterial enzyme system that catalyses L-threonine to L-isoleucine are the first known example of allosteric feedback inhibition.

3. Which of the following is false?
a) Methyl, phosphoryl, adenyl, uridylyl and adenosine diphosphate ribosyl groups are the modifying groups
b) An example of an enzyme regulated by methylation is the methyl-donating chemo taxis protein of bacteria
c) The protein is a part of the system that permits a bacterium to swim towards attractant
d) The methylating agent is S- adenosylmethionine

View Answer

Answer: b [Reason:] An example of an enzyme regulated by methylation is the methyl-accepting chemo taxis protein of bacteria.

4. Which of the following enzyme is responsible for the regulation of biological nitrogen fixation?
a) Dinitrogenase reductase
b) Dinitrogenase oxidase
c) Phosphatase
d) Kinase

View Answer

Answer: a [Reason:] The bacterial enzyme, dinitrogenase reductase is responsible for the regulation of biological nitrogen fixation.

5. Which of the following enzymes catalyze the ADP-ribosylation of key cellular enzymes or proteins?
a) Diphteria toxin and cholera toxin
b) Dinitrogenase reductase
c) Protein phosphatases
d) Kinase

View Answer

Answer: a [Reason:] The enzymes that catalyse the ADP-ribosylation and inactivation of key cellular enzymes or proteins are diphteria toxin and cholera toxin.

6. Removal of phosphoryl groups is catalyzed by
a) Diphteria toxin and cholera toxin
b) Dinitrogenase reductase
c) Protein phosphatases
d) Protein kinases

View Answer

Answer: c [Reason:] The enzymes that catalyze the ADP-ribosylation and inactivation of key cellular enzymes or proteins are diphteria toxin and cholera toxin. Dinitrogenase reductase is responsible for the regulation of biological nitrogen fixation. The attachment of phosphoryl groups to specific amino acid residues is catalyzed by protein kinases.

7. The attachment of phosphoryl groups to specific amino acid residues is catalyzed by
a) Diphteria toxin and cholera toxin
b) Dinitrogenase reductase
c) Protein phosphatases
d) Protein kinases

View Answer

Answer: d [Reason:] The enzymes that catalyse the ADP-ribosylation and inactivation of key cellular enzymes or proteins are diphteria toxin and cholera toxin. Dinitrogenase reductase is responsible for the regulation of biological nitrogen fixation. Removal of phosphoryl groups is catalyzed by Protein phosphatases.

8. Phosphorylase a +2H2O → phosphorylase b + 2Pi
Which of the following is false about this reaction?
a) Phosphorylase a is less active and phosphorylase b is more active
b) Glycogen phosphorylase catalyzes this reaction
c) Phosphorylase b can be transformed back into phosphorylase a by phosphorylase kinase
d) Phosphorylase kinase catalyzes the transfer of phosphoryl groups from ATP to Phosphorylase b

View Answer

Answer: a [Reason:] Phosphorylase a is more active and phosphorylase b is less active.

9. Which of the following takes place due to phosphorylation of isocitrate dehydrogenase?
a) Inhibits the binding of citrate at active site
b) Degrades the enzyme
c) Enhances the substrate-binding affinity
d) No reaction

View Answer

Answer: a [Reason:] The electrostatic repulsion by the phosphoryl group inhibits the binding of citrate at active site.

10. Which of the following enzyme catalyzes a reaction that introduces reduced nitrogen ito cellular metabolism?
a) Bacterial glutamine synthase
b) Bacterial dinitrogenase reductase
c) Bacterial dinitrogenase oxidase
d) Phosphatase

View Answer

Answer: a [Reason:] Bacterial glutamine synthase is one among the most complex regulatory enzymes known. It catalyzes a reaction that introduces reduced nitrogen into cellular metabolism.

11. Which of the following is false about feedback regulation?
a) It is a type of enzymatic activity regulation
b) The synthesis of concerned enzyme is inhibited by interfering with the gene of that enzyme
c) Concentration of enzyme is reduced by the end product
d) The best example is the biosynthesis of L-isoleucine from L-threonine in bacteria

View Answer

Answer: The best example is reduction of HMG CoA reductase enzyme by dietary cholesterol.

12. Which of the following is false?
a) Allosteric modulators may be inhibitory or stimulatory
b) Based on the nature of modulator, allosteric enzymes are of two types
c) Homotropic allosteric enzymes have the substrate and modulator same
d) Heterotropic allosteric enzymes have the substrate and modulator same

View Answer

Answer: d [Reason:] In case of heterotropic enzymes both substrate and modulator are different.

13. In the case of allosteric enzymes what is the graphical representation when initial velocity is plotted against substrate concentration?
a) Straight line with negative slope
b) Hyperbola
c) Sigmoid curve
d) Parabola

View Answer

Answer: c [Reason:] Allosteric enzymes do not obey Michaelis-Menten kinetics. So the curve is not hyperbolic.

14. How many types of enzymatic regulation mechanism occurs in the cells?
a) 2
b) 3
c) 4
d) 5

View Answer

Answer: d [Reason:] Feedback inhibition, reversible covalent modification of enzymes, proteolytic activation of enzyme, feedback regulation and regulation of isozymes.

15. Which is the enzyme that acts as a regulatory enzyme in a four-step metabolic pathway?
a) First enzyme
b) Fourth enzyme
c) Second enzyme
d) Third enzyme

View Answer

Answer: a [Reason:] First reaction is the best place to regulate a metabolic pathway. So, the first enzyme acts as the regulatory enzyme.

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