AP BIOLOGY EXAM QUESTIONS WITH
VERIFIED ANSWERS
A student placed a semipermeable membrane inside a U-shaped channel with two
chambers, as shown. The
membrane permits the movement of water but not salt. The student wants to vary
the rate of osmosis that
occurs across the membrane. Which of the following experimental designs will result
in the fastest net rate
of water movement into chamber A?
A. Placing salt water in chamber A and distilled water in chamber B
B. Placing distilled water in both chambers
C. Placing distilled water in chamber A and salt water in chamber B
D. Placing salt water in both chambers - ANSWER-A. Placing salt water in chamber
A and distilled water in chamber B
During respiration, most ATP is formed as a direct result of the net movement of
A. potassium against a concentration gradient
B. protons down a concentration gradient
C. electrons against a concentration gradient
D. electrons through a channel
E. sodium ions into the cell - ANSWER-B. protons down a concentration gradient
In chloroplasts, ATP is synthesized from ADP plus inorganic phosphate (Pi) in a
reaction catalyzed by ATP
synthase molecules that are embedded in the thylakoid membrane.
Which of the following statements provides evidence to support the claim that no
ATP will be synthesized
in the absence of a proton gradient across the thylakoid membrane?
A. Blocking electron flow from one carrier to the next in the electron transport chains
blocks formation of a
proton gradient in the thylakoid.
B. Increasing the proton concentration difference across the thylakoid membrane is
not associated with a
parallel increase in the rate of ATP synthesis.
C. No ATP is synthesized when channel proteins that allow the free passage of
protons are inserted into the
thylakoid membrane.
D. No ATP is synthesized while the Calvin cycle is synthesizing carbohydrates and
using ATP and NADPH at a high rate. - ANSWER-C. No ATP is synthesized when
channel proteins that allow the free passage of protons are inserted into the
thylakoid membrane.
The enzyme hexokinase catalyzes the conversion of glucose to glucose-6-
phosphate, which is an important
step in glycolysis. The reaction involves the transfer of a phosphate group from ATP
to glucose.
, Either a glucose molecule or a water molecule can fit in the active site of hexokinase.
The presence of a water molecule in hexokinase's active site would result in the
hydrolysis of ATP to ADP instead of the conversion of glucose to glucose-6-
phosphate.
Which of the following statements best helps explain the reaction specificity of
hexokinase?
A. Both glucose and water are polar molecules that form favorable interactions with
charged and polar amino
acid side chains in hexokinase's active site.
B. Both glucose and water have oxygen atoms that can form covalent bonds with the
phosphorus atoms of
phosphate groups.
C. Glucose is an energy-rich organic molecule that can be broken down by glycolysis
to produce ATP, whereas - ANSWER-D. Glucose has the right shape and charge to
cause hexokinase to undergo a structural change needed for
catalysis, whereas water does not.
Which metabolic process is common to both aerobic cellular respiration and
alcoholic fermentation?
A. Krebs cycle
B. Glycolysis
C. Electron transport chain
D. Conversion of pyruvic acid to acetyl CoA
E. Production of a proton gradient - ANSWER-B. Glycolysis
A mutation in the gene coding, for a single-polypeptide enzyme results in the
substitution of the amino acid serine, which has a polar R group, by the amino acid
phenylalanine, which has a non-polar R group. When researchers test the catalysis
of the normal enzyme and the mutated enzyme, they find that the mutated enzyme
has a much lower activity than the normal enzyme does. Which of the following most
likely explains how the amino acid substitution has resulted in decrease catalytic
activity by the mutated enzyme?
A. The substitution decreased the mass of the enzyme so that the mutated enzyme
binds more weakly yo the substrate than the normal enzyme does.
B. The substitution altered the secondary and tertiary structure of the enzyme so that
the mutated enzyme folds into a different shape than the normal enzyme does
C. The substitution caused many copied of the mutated enzyme to cluster together
and compete for subs - ANSWER-B. The substitution altered the secondary and
tertiary structure of the enzyme so that the mutated enzyme folds into a different
shape than the normal enzyme does
A typical bag of fertilizer contains high levels of nitrogen, phosphorus, and potassium
but trace amounts of magnesium and calcium. Which of the following best matches
the fertilizer component with the molecule in which it will be incorporated by
organisms in the area?
A. Nitrogen will be incorporated into nucleic acids
B. Phosphorus will be incorporated into amino acids
C. Potassium will be incorporated into lipids
D. Magnesium will be incorporated into carbohydrates - ANSWER-A. Nitrogen will be
incorporated into nucleic acids
VERIFIED ANSWERS
A student placed a semipermeable membrane inside a U-shaped channel with two
chambers, as shown. The
membrane permits the movement of water but not salt. The student wants to vary
the rate of osmosis that
occurs across the membrane. Which of the following experimental designs will result
in the fastest net rate
of water movement into chamber A?
A. Placing salt water in chamber A and distilled water in chamber B
B. Placing distilled water in both chambers
C. Placing distilled water in chamber A and salt water in chamber B
D. Placing salt water in both chambers - ANSWER-A. Placing salt water in chamber
A and distilled water in chamber B
During respiration, most ATP is formed as a direct result of the net movement of
A. potassium against a concentration gradient
B. protons down a concentration gradient
C. electrons against a concentration gradient
D. electrons through a channel
E. sodium ions into the cell - ANSWER-B. protons down a concentration gradient
In chloroplasts, ATP is synthesized from ADP plus inorganic phosphate (Pi) in a
reaction catalyzed by ATP
synthase molecules that are embedded in the thylakoid membrane.
Which of the following statements provides evidence to support the claim that no
ATP will be synthesized
in the absence of a proton gradient across the thylakoid membrane?
A. Blocking electron flow from one carrier to the next in the electron transport chains
blocks formation of a
proton gradient in the thylakoid.
B. Increasing the proton concentration difference across the thylakoid membrane is
not associated with a
parallel increase in the rate of ATP synthesis.
C. No ATP is synthesized when channel proteins that allow the free passage of
protons are inserted into the
thylakoid membrane.
D. No ATP is synthesized while the Calvin cycle is synthesizing carbohydrates and
using ATP and NADPH at a high rate. - ANSWER-C. No ATP is synthesized when
channel proteins that allow the free passage of protons are inserted into the
thylakoid membrane.
The enzyme hexokinase catalyzes the conversion of glucose to glucose-6-
phosphate, which is an important
step in glycolysis. The reaction involves the transfer of a phosphate group from ATP
to glucose.
, Either a glucose molecule or a water molecule can fit in the active site of hexokinase.
The presence of a water molecule in hexokinase's active site would result in the
hydrolysis of ATP to ADP instead of the conversion of glucose to glucose-6-
phosphate.
Which of the following statements best helps explain the reaction specificity of
hexokinase?
A. Both glucose and water are polar molecules that form favorable interactions with
charged and polar amino
acid side chains in hexokinase's active site.
B. Both glucose and water have oxygen atoms that can form covalent bonds with the
phosphorus atoms of
phosphate groups.
C. Glucose is an energy-rich organic molecule that can be broken down by glycolysis
to produce ATP, whereas - ANSWER-D. Glucose has the right shape and charge to
cause hexokinase to undergo a structural change needed for
catalysis, whereas water does not.
Which metabolic process is common to both aerobic cellular respiration and
alcoholic fermentation?
A. Krebs cycle
B. Glycolysis
C. Electron transport chain
D. Conversion of pyruvic acid to acetyl CoA
E. Production of a proton gradient - ANSWER-B. Glycolysis
A mutation in the gene coding, for a single-polypeptide enzyme results in the
substitution of the amino acid serine, which has a polar R group, by the amino acid
phenylalanine, which has a non-polar R group. When researchers test the catalysis
of the normal enzyme and the mutated enzyme, they find that the mutated enzyme
has a much lower activity than the normal enzyme does. Which of the following most
likely explains how the amino acid substitution has resulted in decrease catalytic
activity by the mutated enzyme?
A. The substitution decreased the mass of the enzyme so that the mutated enzyme
binds more weakly yo the substrate than the normal enzyme does.
B. The substitution altered the secondary and tertiary structure of the enzyme so that
the mutated enzyme folds into a different shape than the normal enzyme does
C. The substitution caused many copied of the mutated enzyme to cluster together
and compete for subs - ANSWER-B. The substitution altered the secondary and
tertiary structure of the enzyme so that the mutated enzyme folds into a different
shape than the normal enzyme does
A typical bag of fertilizer contains high levels of nitrogen, phosphorus, and potassium
but trace amounts of magnesium and calcium. Which of the following best matches
the fertilizer component with the molecule in which it will be incorporated by
organisms in the area?
A. Nitrogen will be incorporated into nucleic acids
B. Phosphorus will be incorporated into amino acids
C. Potassium will be incorporated into lipids
D. Magnesium will be incorporated into carbohydrates - ANSWER-A. Nitrogen will be
incorporated into nucleic acids
