University of Illinois Urbana-Champaign MCB 150 Test 1 |
Questions with 100% Verified Answers | Latest Update
Question:
Which of the following is a covalent modification that can affect enzyme activity?
A) pH
B) Allosteric activation
C) Phosphorylation
D) Competitive inhibition
Answer:
C) Phosphorylation
Question:
Which of the following is a chemical reaction?
A) Changing a carbon atom to a nitrogen atom by radioactive
decay.
B) Dissolving a lump of sugar in a cup of coffee.
C) Making a hydrogen bond between a water molecule and a
sugar molecule.
D) Melting ice.
E) None of the above.
Answer:
E) None of the above.
Question:
Which of the following is a chemical reaction?
A)Changing a carbon atom to a nitrogen atom by radioactive
decay.
B)Dissolving a lump of sugar in a cup of coffee.
C)Making a hydrogen bond between a water molecule and a
sugar molecule.
D)Melting ice.
E)None of the above.
Answer:
E)None of the above.
Question:
Which of the following is true of activation energy? (a) Molecules usually get it from thermal energy.
(b) Molecules usually get it by breaking bonds. (c) It's the energy difference between reactants and
products. (d)Both (a) and (c). (e): (a), (b), and (c).
Answer:
(a) Molecules usually get it from thermal energy.
,Question:
Which fact is most important in explaining how molecules convert thermal energy to activation
energy (EA)?
A)Potential energy increases when molecules make bonds.
B)Thermal energy is a form of potential energy.
C)Distortion decreases a molecule's potential energy.
D)Potential energy decreases when molecules make bonds.
E)Distortion increases a molecule's potential energy.
Answer:
E)Distortion increases a molecule's potential energy.
Question:
Which statement is true of the transition state? (a) It can break apart to yield either reactants or
products. (b) It is extremely unstable and lasts only an instant. (c) It has less potential energy than
the reactants but more than the products. (d)Both (a) and (b). (e)Both (b) and (c).
Answer:
(d) Both (a) It can break apart to yield either reactants or products. and (b) It is extremely unstable
and lasts only an instant.
Question:
Which statement most accurately explains why ATP hydrolysis is highly exergonic?
A)ATP contains the carbohydrate ribose which stores a large
amount of chemical energy.
B)Energy is released when a phosphate group is added.
C)There is a large drop in potential energy because charge
repulsion is reduced
D)There is a large increase in potential energy because
charge repulsion is reduced.
Answer:
C)There is a large drop in potential energy because charge repulsion is reduced
Question:
Which of the following can change the shape of an enzyme?
A) pH
B) phosphorylation
C) temperature
D) all of the above
Answer:
D) all of the above
, Question:
Which statement most accurately explains how allosteric regulation can change an enzyme's
catalytic activity?
A) In allosteric inhibition, a regulatory molecule binds to a
location other than the active site, resulting in a change in enzyme shape that allows the active site
to bind substrate.
B) In allosteric activation, a regulatory molecule binds to a
location other than the active site, resulting in a change in enzyme shape that allows the active site
to bind substrate.
C) In allosteric inhibition, a regulatory molecule binds to the
active site, blocking substrate binding.
D) In allosteric activation, a regulatory molecule binds to the
active site, allowing substrate binding.
Answer:
B) In allosteric activation, a regulatory molecule binds to a location other than the active
site, resulting in a change in enzyme shape that allows the active site to bind substrate.
Question:
Which of these is NOT a lipid?
A) RNA
B) wax
C) steroids
D) cholesterol
E) phospholipid
Answer:
A) RNA
Question:
Which of the following scenarios would you predict to be responsible for activating this enzyme?
A) The sugar cleaves the enzyme so it is now in an active
conformation.
B) The sugar phosphorylates the enzyme, triggering a
conformational change.
C) The sugar binds to the active site and competes with the
normal substrate.
D) The sugar binds to the enzyme and changes the
conformation of the active site.
Answer:
D) The sugar binds to the enzyme and changes the conformation of the active site.
Question:
Researchers can analyze the atomic structure of enzymes during catalysis. In one recent study,
investigators found that the transition state included the formation of a free radical and that a
coenzyme bound to the active site donated an electron to help stabilize the free radical. How would
the reaction rate and the stability of the transition state change if the coenzyme were not available?
Questions with 100% Verified Answers | Latest Update
Question:
Which of the following is a covalent modification that can affect enzyme activity?
A) pH
B) Allosteric activation
C) Phosphorylation
D) Competitive inhibition
Answer:
C) Phosphorylation
Question:
Which of the following is a chemical reaction?
A) Changing a carbon atom to a nitrogen atom by radioactive
decay.
B) Dissolving a lump of sugar in a cup of coffee.
C) Making a hydrogen bond between a water molecule and a
sugar molecule.
D) Melting ice.
E) None of the above.
Answer:
E) None of the above.
Question:
Which of the following is a chemical reaction?
A)Changing a carbon atom to a nitrogen atom by radioactive
decay.
B)Dissolving a lump of sugar in a cup of coffee.
C)Making a hydrogen bond between a water molecule and a
sugar molecule.
D)Melting ice.
E)None of the above.
Answer:
E)None of the above.
Question:
Which of the following is true of activation energy? (a) Molecules usually get it from thermal energy.
(b) Molecules usually get it by breaking bonds. (c) It's the energy difference between reactants and
products. (d)Both (a) and (c). (e): (a), (b), and (c).
Answer:
(a) Molecules usually get it from thermal energy.
,Question:
Which fact is most important in explaining how molecules convert thermal energy to activation
energy (EA)?
A)Potential energy increases when molecules make bonds.
B)Thermal energy is a form of potential energy.
C)Distortion decreases a molecule's potential energy.
D)Potential energy decreases when molecules make bonds.
E)Distortion increases a molecule's potential energy.
Answer:
E)Distortion increases a molecule's potential energy.
Question:
Which statement is true of the transition state? (a) It can break apart to yield either reactants or
products. (b) It is extremely unstable and lasts only an instant. (c) It has less potential energy than
the reactants but more than the products. (d)Both (a) and (b). (e)Both (b) and (c).
Answer:
(d) Both (a) It can break apart to yield either reactants or products. and (b) It is extremely unstable
and lasts only an instant.
Question:
Which statement most accurately explains why ATP hydrolysis is highly exergonic?
A)ATP contains the carbohydrate ribose which stores a large
amount of chemical energy.
B)Energy is released when a phosphate group is added.
C)There is a large drop in potential energy because charge
repulsion is reduced
D)There is a large increase in potential energy because
charge repulsion is reduced.
Answer:
C)There is a large drop in potential energy because charge repulsion is reduced
Question:
Which of the following can change the shape of an enzyme?
A) pH
B) phosphorylation
C) temperature
D) all of the above
Answer:
D) all of the above
, Question:
Which statement most accurately explains how allosteric regulation can change an enzyme's
catalytic activity?
A) In allosteric inhibition, a regulatory molecule binds to a
location other than the active site, resulting in a change in enzyme shape that allows the active site
to bind substrate.
B) In allosteric activation, a regulatory molecule binds to a
location other than the active site, resulting in a change in enzyme shape that allows the active site
to bind substrate.
C) In allosteric inhibition, a regulatory molecule binds to the
active site, blocking substrate binding.
D) In allosteric activation, a regulatory molecule binds to the
active site, allowing substrate binding.
Answer:
B) In allosteric activation, a regulatory molecule binds to a location other than the active
site, resulting in a change in enzyme shape that allows the active site to bind substrate.
Question:
Which of these is NOT a lipid?
A) RNA
B) wax
C) steroids
D) cholesterol
E) phospholipid
Answer:
A) RNA
Question:
Which of the following scenarios would you predict to be responsible for activating this enzyme?
A) The sugar cleaves the enzyme so it is now in an active
conformation.
B) The sugar phosphorylates the enzyme, triggering a
conformational change.
C) The sugar binds to the active site and competes with the
normal substrate.
D) The sugar binds to the enzyme and changes the
conformation of the active site.
Answer:
D) The sugar binds to the enzyme and changes the conformation of the active site.
Question:
Researchers can analyze the atomic structure of enzymes during catalysis. In one recent study,
investigators found that the transition state included the formation of a free radical and that a
coenzyme bound to the active site donated an electron to help stabilize the free radical. How would
the reaction rate and the stability of the transition state change if the coenzyme were not available?
