AP BIO UNIT 3 - ENZYMES AND
CELLULAR RESPIRATION TEST
QUESTIONS WITH COMPLETE
SOLUTIONS
Where does the carbon dioxide used to make carbohydrates come from? -
ANSWER-Plants and other organisms mainly get their carbon dioxide from the
environment.
APC Question: A researcher proposes a model of an enzyme-catalyzed reaction in
which a reactant is converted to a product. The model is based on the idea that the
reactant passes through a transition state within the enzyme-substrate complex
before the reactant is converted to the product. Which of the following statements
best helps explain how the enzyme speeds up the reaction?
a.) The enzyme's active site binds to and stabilizes the reactant, which decreases
the free-energy change of the reaction.
b.) The enzyme's active site binds to and stabilizes the transition state, which
decreases the activation energy of the reaction.
c.) The enzyme's active site binds to and stabilizes the product, which increases the
amount of energy released by the reaction.
d.) The enzyme's active site binds to and stabilizes both the reactant and the product
at the same time, which increases the reaction's equilibrium constant. - ANSWER-
Answer: B - the enzyme's active site binds to and stabilizes the transition state,
which decreases the activation energy of the reaction.
APC Question: Alcohol dehydrogenase (ADH) is an enzyme that aids in the
decomposition of ethyl alcohol (C2H5OH) into nontoxic substances. Methyl alcohol
acts as a competitive inhibitor of ethyl alcohol by competing for the same active site
on ADH. When attached to ADH, methyl alcohol is converted to formaldehyde, which
is toxic in the body. Which of the following statements best predicts the effect of
increasing the concentration of substrate (ethyl alcohol), while keeping the
concentration of the inhibitor (methyl alcohol) constant?
a.) There will be an increase in formaldehyde because ADH activity increases.
b.) Competitive inhibition will be terminated because ethyl alcohol will bind to methyl
alcohol and decrease ADH activity.
c.) The peptide bonds in the active site of the enzyme will be denatured, inhibiting
the enzyme.
, d.) Competitive inhibition will decrease because the proportion of the active sites occ
- ANSWER-Answer: D - Competitive inhibition will decrease because the proportion
of the active sites occupied by substrate will increase.
APC Question: Amylase is a protein that catalyzes the conversion of starch to simple
sugars. Amylase activity in an aqueous solution can be measured by using iodine as
a starch indicator. A solution containing iodine and starch will have a dark-blue color,
whereas a solution containing iodine but no starch will have a light-brown color. The
color change of an iodine solution from dark blue to light brown can be used to
measure the rate at which starch is converted to simple sugars.
A student designs an experiment to investigate the effect of environmental pH on
amylase function. The design of the experiment is presented in Table 1. Which of the
following statements best justifies the inclusion of test tube VV as a control in the
experiment?
a.) It will provide a measurement of amylase activity at an acidic pH.
b.) It will provide a measurement of amylase activity at a basic pH.
c.) It will show the color change t - ANSWER-Answer: C - It will show the color
change that occurs in the absence of enzyme activity
APC Question: A researcher claims that some bacteria contain factors that influence
the function of a particular enzyme but other bacteria do not. To test the claim
experimentally, the researcher will grow two different bacterial strains in separate
liquid cultures and isolate the contents of the cells in each culture. The researcher
will add different combinations of cellular contents, substrate, and enzyme to test
tubes containing a buffer solution adjusted to the optimal pH of the enzyme and then
measure the rate of product formation. The design of the researcher's experiment is
presented in Table 1.
Which of the following statements justifies the inclusion of test tubes 3 and 7 in the
experiment?
a.) They will show whether the isolated cellular contents have enzymatic activity.
b.) They will show whether environmental pH affects the function of the enzyme.
c.) They will show the rate of product formation in - ANSWER-Answer: A - they will
show whether the isolated cellular contents have enzymatic activity.
APC Question: A researcher designs an experiment to investigate the effect of
environmental temperature on the function of an enzyme. For each trial included in
the experiment, the researcher will add the enzyme and its substrate to an aqueous
buffer solution and then measure the amount of product formed over 20 minutes.
Which of the following must remain the same for all trials of this experiment?
a.) The initial concentration of the substrate
CELLULAR RESPIRATION TEST
QUESTIONS WITH COMPLETE
SOLUTIONS
Where does the carbon dioxide used to make carbohydrates come from? -
ANSWER-Plants and other organisms mainly get their carbon dioxide from the
environment.
APC Question: A researcher proposes a model of an enzyme-catalyzed reaction in
which a reactant is converted to a product. The model is based on the idea that the
reactant passes through a transition state within the enzyme-substrate complex
before the reactant is converted to the product. Which of the following statements
best helps explain how the enzyme speeds up the reaction?
a.) The enzyme's active site binds to and stabilizes the reactant, which decreases
the free-energy change of the reaction.
b.) The enzyme's active site binds to and stabilizes the transition state, which
decreases the activation energy of the reaction.
c.) The enzyme's active site binds to and stabilizes the product, which increases the
amount of energy released by the reaction.
d.) The enzyme's active site binds to and stabilizes both the reactant and the product
at the same time, which increases the reaction's equilibrium constant. - ANSWER-
Answer: B - the enzyme's active site binds to and stabilizes the transition state,
which decreases the activation energy of the reaction.
APC Question: Alcohol dehydrogenase (ADH) is an enzyme that aids in the
decomposition of ethyl alcohol (C2H5OH) into nontoxic substances. Methyl alcohol
acts as a competitive inhibitor of ethyl alcohol by competing for the same active site
on ADH. When attached to ADH, methyl alcohol is converted to formaldehyde, which
is toxic in the body. Which of the following statements best predicts the effect of
increasing the concentration of substrate (ethyl alcohol), while keeping the
concentration of the inhibitor (methyl alcohol) constant?
a.) There will be an increase in formaldehyde because ADH activity increases.
b.) Competitive inhibition will be terminated because ethyl alcohol will bind to methyl
alcohol and decrease ADH activity.
c.) The peptide bonds in the active site of the enzyme will be denatured, inhibiting
the enzyme.
, d.) Competitive inhibition will decrease because the proportion of the active sites occ
- ANSWER-Answer: D - Competitive inhibition will decrease because the proportion
of the active sites occupied by substrate will increase.
APC Question: Amylase is a protein that catalyzes the conversion of starch to simple
sugars. Amylase activity in an aqueous solution can be measured by using iodine as
a starch indicator. A solution containing iodine and starch will have a dark-blue color,
whereas a solution containing iodine but no starch will have a light-brown color. The
color change of an iodine solution from dark blue to light brown can be used to
measure the rate at which starch is converted to simple sugars.
A student designs an experiment to investigate the effect of environmental pH on
amylase function. The design of the experiment is presented in Table 1. Which of the
following statements best justifies the inclusion of test tube VV as a control in the
experiment?
a.) It will provide a measurement of amylase activity at an acidic pH.
b.) It will provide a measurement of amylase activity at a basic pH.
c.) It will show the color change t - ANSWER-Answer: C - It will show the color
change that occurs in the absence of enzyme activity
APC Question: A researcher claims that some bacteria contain factors that influence
the function of a particular enzyme but other bacteria do not. To test the claim
experimentally, the researcher will grow two different bacterial strains in separate
liquid cultures and isolate the contents of the cells in each culture. The researcher
will add different combinations of cellular contents, substrate, and enzyme to test
tubes containing a buffer solution adjusted to the optimal pH of the enzyme and then
measure the rate of product formation. The design of the researcher's experiment is
presented in Table 1.
Which of the following statements justifies the inclusion of test tubes 3 and 7 in the
experiment?
a.) They will show whether the isolated cellular contents have enzymatic activity.
b.) They will show whether environmental pH affects the function of the enzyme.
c.) They will show the rate of product formation in - ANSWER-Answer: A - they will
show whether the isolated cellular contents have enzymatic activity.
APC Question: A researcher designs an experiment to investigate the effect of
environmental temperature on the function of an enzyme. For each trial included in
the experiment, the researcher will add the enzyme and its substrate to an aqueous
buffer solution and then measure the amount of product formed over 20 minutes.
Which of the following must remain the same for all trials of this experiment?
a.) The initial concentration of the substrate
