1. Which of the following is true about the structure of hexokinase?
a) U-shaped
b) T-shaped
c) E-shaped
d) G-shaped
Explanation: Hexokinase has a U-shaped structure.
2. Which of the following is true?
a) Xylose is stereo chemically similar to glucose but one carbon shorter
b) Xylose binds to hexokinase in a position where it can be phosphorylated
c) Addition of xylose increases the rate of ATP hydrolysis
d) The binding of xylose is sufficient to induce a change in hexokinase to its active conformation
Explanation: Xylose binds to hexokinase at a position where it cannot be phosphorylated.
3. Which of the following catalyzes the reversible degradation of 2-phosphoglycerate to phosphoenolpyruvate?
a) Chymotrypsin
b) Hexokinase
c) Enolase
d) Trypsin
Explanation: Enolase catalyzes the reversible degradation of 2-phosphoglycerate to phosphoenolpyruvate.
4. Which of the following catalyzes the reversible reaction of β-D-Glucose to glucose 6-phosphate?
a) Chymotrypsin
b) Hexokinase
c) Enolase
d) Trypsin
Explanation: Hexokinase catalyzes the reversible reaction of β-D-Glucose to glucose 6-phosphate.
5. Which of the following is false about lysozyme?
a) It is an antibacterial agent found in tears and egg white
b) The substrate of lysozyme is peptidoglycan
c) Lysozyme cleaves (β1 → 4) glycosidic C-O bonds between two types of sugar residue in the molecule NAM and NAG
d) It is a bisubstrate enzyme
Explanation: Hexokinase is the bisubstrate enzymed
6. 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
Explanation: 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.
7. 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
Explanation: The bacterial enzyme system that catalyses L-threonine to L-isoleucine are the first known example of allosteric feedback inhibition.
8. 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
Explanation: An example of an enzyme regulated by methylation is the methyl-accepting chemo taxis protein of bacteria.
9. Which of the following enzyme is responsible for the regulation of biological nitrogen fixation?
a) Dinitrogenase reductase
b) Dinitrogenase oxidase
c) Phosphatase
d) Kinase
Explanation: The bacterial enzyme, dinitrogenase reductase is responsible for the regulation of biological nitrogen fixation.
10. 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
Explanation: The enzymes that catalyse the ADP-ribosylation and inactivation of key cellular enzymes or proteins are diphteria toxin and cholera toxin.