AP Biology HW Due Monday Oct 7, 2013

Email your answer to tan.lam@yesprep.org

36 . Which of the following statements correctly describe(s) the role(s) of heat and temperature in biological reactions?
A. Heat from the environment is necessary for substrates to get over the activation energy barrier.
B. Increasing temperature increases the kinetic energy of the substrates.
C. Increasing the temperature will increase the rate of enzyme-catalyzed reactions.
D. The first and second choices are correct.
E. The first, second, and third choices are correct.

37 . Above a certain substrate concentration, the rate of an enzyme-catalyzed reaction drops as the enzymes become saturated. Which of the following would lead to a faster conversion of substrate into product under these saturated conditions?
A. an increase in concentration of enzyme
B. increasing the temperature by a few degrees
C. increasing the substrate concentration
D. The first and second choices are correct.
E. The first, second, and third choices are correct.

38 . Which of the following environments or actions does not affect the rate of an enzyme reaction?
A. heating the enzyme
B. cooling the enzyme
C. substrate concentration
D. pH
E. all of the above

39 . Enzyme activity is affected by pH because _____.
A. most substrates don’t function well at high or low pH
B. high or low pH may disrupt hydrogen bonding or ionic interactions and thus change the shape of the active site
C. low pH will denature all enzymes
D. changes in pH can cause loss of cofactors from the enzyme
E. the binding of hydrogen ions to the enzyme absorbs energy and thus there may not be enough energy to overcome the activation energy barrier

40 . Which of these statements about enzyme inhibitors is true?
A. A competitive inhibitor binds to the enzyme at a place that is separate from the active site.
B. The action of competitive inhibitors may be reversible or irreversible.
C. A noncompetitive inhibitor does not change the shape of the active site.
D. When the product of an enzyme or an enzyme sequence acts as its inhibitor, this is known as positive feedback.
E. Inhibition of enzyme function by compounds that are not substrates is something that only occurs under controlled conditions in the laboratory.

41 . Succinylcholine is structurally almost identical to acetylcholine. If succinylcholine is added to a mixture that contains acetylcholine and the enzyme that hydrolyzes acetylcholine (but not succinylcholine), the rate of acetylcholine hydrolysis is decreased. Subsequent addition of more acetylcholine restores the original rate of acetylcholine hydrolysis. Which of the following correctly explains this observation?
A. Succinylcholine must be a competitive inhibitor with acetylcholine.
B. Succinylcholine must be an allosteric regulator for this enzyme.
C. The active site must have the wrong configuration to permit succinylcholine binding.
D. Succinylcholine must be a non-competitive inhibitor.
E. The activation energy barrier for succinylcholine hydrolysis is higher than for acetylcholine hydrolysis.

42 . The process of stabilizing the structure of an enzyme in its active form by the binding of a molecule is an example of _____.
A. feedback inhibition
B. competitive inhibition
C. allosteric regulation
D. non-competitive inhibition
E. cooperativity

43 . Which, if any, of the following statements is not true about allosteric proteins?
A. They are sensitive to environmental conditions.
B. They are acted on by inhibitors.
C. They exist in active and inactive conformations.
D. They can bind to a range of substrates.
E. All of the above statements are true of allosteric proteins.

44 . The binding of an allosteric inhibitor to an enzyme causes the rate of product formation by the enzyme to decrease. Which of the following best explains why this decrease occurs?
A. The allosteric inhibitor binds to the active site, preventing the substrate from binding.
B. The allosteric inhibitor causes free energy change of the reaction to increase.
C. The allosteric inhibitor causes a structural change in the enzyme that prevents the substrate from binding at the active site.
D. The allosteric inhibitor lowers the temperature of the active site.
E. The allosteric inhibitor binds to the substrate and prevents it from binding at the active site.

45 . Under most conditions, the supply of energy by catabolic pathways is regulated by the demand for energy by anabolic pathways. Considering the role of ATP formation and hydrolysis in energy coupling of anabolic and catabolic pathways, which of the following statements is most likely to be true?
A. High levels of ADP act as an allosteric inhibitor of catabolic pathways.
B. High levels of ATP act as an allosteric activator of anabolic pathways.
C. High levels of ATP act as an allosteric activator of catabolic pathways.
D. High levels of ADP act as an allosteric activator of catabolic pathways
E. High levels of ADP act as an allosteric inhibitor of anabolic pathways.

Bookmark the permalink.

Leave a Reply

Your email address will not be published. Required fields are marked *