This set of Biochemistry Multiple Choice Questions & Answers (MCQs) focuses on “Regulation of Metabolic Pathways”.
1. Which out of the following statements is true about the 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
Explanation: 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
c) Steady state
Explanation: The rate of breakdown of metabolites is termed as a steady state.
3. Diminished delivery of oxygen to tissues is termed as ___________
Explanation: Diminished delivery of oxygen to tissues is termed as hypoxia.
4. Diminished flow of blood to tissues is termed as ___________
Explanation: 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
Explanation: 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
c) Allosteric regulation
Explanation: 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
Explanation: A high insulin/glucagon inactivates lipolysis.
8. Which of the following type of metabolites is used for generating glucose under severe starvation conditions?
a) Amino acids
Explanation: 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
Explanation: Brain does not use amino acids directly but glucose derived from glucogenic amino acids in the liver.
10. Which one of the following statements about the control of enzyme activity by phosphorylation is correct?
a) Phosphorylation of an enzyme results in a 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
Explanation: Phosphorylation of enzyme is reversible; phosphorylation is not carried out by phosphoprotein phosphatases.
Sanfoundry Global Education & Learning Series – Biochemistry.
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