41) Where do substrates bind to enzymes?

A) in the active site

B) anywhere

C) in the substrate groove

D) in the effector site

42) Which of the following is true of vitamins?

A) They serve as a major energy source for cells.

B) They are the main component of enzymes.

C) They can serve as enzymes.

D) They can serve as coenzymes.

43) The function of chymotrypsin is to:

A) break down proteins into amino acids.

B) synthesize glycogen.

C) synthesize proteins.

D) break down glycogen into glucose.

44) Which of the following describes a transition state molecule?

A) the distorted shape the product takes while being released from the enzyme

B) the distorted shape the substrate takes when being converted by an enzyme into product

C) the distorted shape the enzyme takes when converting substrate into product

D) the distorted shape a coenzyme takes while it is bound to an enzyme

45) Methyl alcohol, also known as wood alcohol, is a common solvent and paint remover. It ispoisonous if accidentally swallowed. The enzyme alcohol dehydrogenase in the liver converts methyl alcohol into formaldehyde, which then gets converted into a toxic product. Grain alcohol, ethyl alcohol, is also acted upon by alcohol dehydrogenase. One antidote for methyl alcohol poisoning is to make a person drink a lot of ethyl alcohol. This blocks the active site of theenzyme so that it can’t bind to and break down the methyl alcohol. In this capacity, the ethyl alcohol is acting as a/an:

A) allosteric regulator.

B) coenzyme.

C) competitive inhibtor.

D) precursor.

46) People with high cholesterol levels often take drugs in an attempt to lower their cholesterol levels. One such drug is Lipitor. How does this drug work?

A) It enhances the activity of enzymes that help break down cholesterol in the body.

B) It prevents cholesterol from the diet from being absorbed in the small intestine.

C) It acts as a competitive inhibitor by binding to the active site of enzymes that normally produce cholesterol.

D) It increases the activation energy of enzymes needed to produce cholesterol.

47) What mechanism is used to finely tune enzyme activity according to the needs of the cell?

A) competitive inhibition

B) coupled reactions

C) enzyme specificity

D) allosteric regulation

48) Which of the following is true of allosteric enzymes?

A) Their activity can be reduced when the product binds the enzyme.

B) Their activity can be reduced when the substrate binds the enzyme.

C) Their coenzyme is removed when the product binds the enzyme.

D) Their activity can be increased by competitive inhibitors.

49) Why is allosteric regulation important to a cell?

A) It allows the cell to control how much of a metabolic product is produced.

B) It allows the cell to switch to other sources of energy besides ATP.

C) It reduces the cell’s need for coenzymes.

D) It allows the cell to control how much activation energy is required for enzymatic reactions.

50) In allosteric enzyme regulation, which of the following is false about the molecules that can inhibit enzyme activity?

A) They can cause the active site to have a poor shape for binding substrate.

B) They can increase substrate binding.

C) They cause a change in the enzyme’s shape.

D) They can bind to a site other than the active site.

51) When a product binds to an allosteric enzyme to slow its reaction, it does which of the following?

A) binds to the active site, blocking the binding of substrate

B) binds to a site other than the active site, changing the shape of the active site and decreasing the binding of substrate

C) binds to the substrate, blocking its binding of the active site

D) binds to the product production site, stopping the production of product