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AMAP
AMAP
PRACTICE.pdf(*((&#*!(*#*($$(*($(*$Y(&*&$(*)&*)((&$*^$&*&$
BIO
BIO
PRACTICE.pdf(*((&#*!(*#*($$(*($(*$Y(&*&$(*)&*)((&$*^$&*&$
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AP Biology Scoring Guide
Unit 3 Test
1. 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?
The enzyme’s active site binds to and stabilizes the reactant, which decreases the free-energy change of the
A
reaction.
The enzyme’s active site binds to and stabilizes the transition state, which decreases the activation energy of
B
the reaction.
The enzyme’s active site binds to and stabilizes the product, which increases the amount of energy released
C
by the reaction.
The enzyme’s active site binds to and stabilizes both the reactant and the product at the same time, which
D
increases the reaction’s equilibrium constant.
2. Alcohol dehydrogenase ( ) is an enzyme that aids in the decomposition of ethyl alcohol
into nontoxic substances. Methyl alcohol acts as a competitive inhibitor of ethyl alcohol by competing for
the same active site on . When attached to , 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 activity increases.
Competitive inhibition will be terminated because ethyl alcohol will bind to methyl alcohol and decrease
B
activity.
C The peptide bonds in the active site of the enzyme will be denatured, inhibiting the enzyme.
Competitive inhibition will decrease because the proportion of the active sites occupied by substrate will
D
increase.
3. A researcher claims that increased atmospheric carbon dioxide levels cause increased growth rates in plants.
Which of the following statements best supports the researcher’s claim?
Copyright © 2020. The College Board. These materials are part of a College Board program. Use or distribution of these materials online or in print
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Page 1 of 47
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AMAPAMAPBIO
AMAP
BIO
PRACTICE.pdf(*((&#*!(*#*($$(*($(*$Y(&*&$(*)&*)((&$*^$&*&$
BIO
PRACTICE.pdf(*((&#*!(*#*($$(*($(*$Y(&*&$(*)&*)((&$*^$&*&$
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,10/13/2026Page
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AMAP
PRACTICE.pdf(*((&#*!(*#*($$(*($(*$Y(&*&$(*)&*)((&$*^$&*&$
BIO
BIO
PRACTICE.pdf(*((&#*!(*#*($$(*($(*$Y(&*&$(*)&*)((&$*^$&*&$
PRACTICE.pdf(*((&#*!(*#*($$(*($(*$Y(&*&$(*)&*)((&$*^$&*&$
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VJyvhjbnoP+_IREOLKDJ(UWRORWUOI
VJyvhjbnoP+_IREOLKDJ(UWRORWUO
AP Biology Scoring Guide
Unit 3 Test
Atmospheric carbon dioxide is produced by the burning of fossil fuels, which are formed from the remains of
A
living organisms such as plants.
Atmospheric carbon dioxide is a byproduct of cellular respiration, which is a metabolic process that occurs
B
in plants and other living organisms.
Atmospheric carbon dioxide typically enters plant leaves through stomata, which plants rely on for
C
regulating gas exchange with the atmosphere.
Atmospheric carbon dioxide is the raw material for photosynthesis, which plants rely on for producing
D
sugars and other organic compounds.
4. The figures below illustrate the similarities between ATP synthesis in mitochondria and chloroplasts.
The figures can best assist in answering which of the following questions?
Copyright © 2020. The College Board. These materials are part of a College Board program. Use or distribution of these materials online or in print
beyond your school’s participation in the program is prohibited.
Page 2 of 47
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AMAPAMAPBIO
AMAP
BIO
PRACTICE.pdf(*((&#*!(*#*($$(*($(*$Y(&*&$(*)&*)((&$*^$&*&$
BIO
PRACTICE.pdf(*((&#*!(*#*($$(*($(*$Y(&*&$(*)&*)((&$*^$&*&$
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,10/13/2026Page
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AMAP
PRACTICE.pdf(*((&#*!(*#*($$(*($(*$Y(&*&$(*)&*)((&$*^$&*&$
BIO
BIO
PRACTICE.pdf(*((&#*!(*#*($$(*($(*$Y(&*&$(*)&*)((&$*^$&*&$
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VJyvhjbnoP+_IREOLKDJ(UWRORWUOI
VJyvhjbnoP+_IREOLKDJ(UWRORWUO
AP Biology Scoring Guide
Unit 3 Test
A Do electron transport chains create a gradient so that ATP synthase can generate ATP molecules?
B What are the sources of energy that drive mitochondrial and chloroplast electron transport systems?
What is the optimal temperature at which ATP synthase chemically converts ADP and a phosphate group
C
into one molecule of ATP?
What is the evolutionary relationship between the ATP synthase in mitochondria and the ATP synthase in
D
chloroplasts?
5. A researcher claims that different metabolic pathways allow bacteria to use different molecules as sources of
matter and energy.
Which of the following statements best helps justify the researcher’s claim by providing a relevant example?
A Rhizobia bacteria form close associations with the roots of bean plants.
B E. coli bacteria reproduce in liquid media containing either glucose or galactose.
C The antibiotic rifampicin inhibits the growth of some bacterial strains but not of others.
D Some viruses that infect bacteria reproduce by either the lysogenic cycle or the lytic cycle.
To investigate bacterial metabolism, a researcher divided a population (culture) of Staphylococcus capitis bacteria
into two sets of culture tubes containing glucose. The researcher added a chemical to one set of tubes and measured
the of the cultures at -minute intervals as the bacteria metabolized the glucose into lactic acid. The data are
shown in Table 1.
TABLE 1. AVERAGE CHANGE IN IN CONTROL AND TREATMENT GROUPS OVER A -MINUTE PERIOD
Average of Control Average of Treatment
Time (min)
( ) ( )
Copyright © 2020. The College Board. These materials are part of a College Board program. Use or distribution of these materials online or in print
beyond your school’s participation in the program is prohibited.
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AMAP
BIO
PRACTICE.pdf(*((&#*!(*#*($$(*($(*$Y(&*&$(*)&*)((&$*^$&*&$
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PRACTICE.pdf(*((&#*!(*#*($$(*($(*$Y(&*&$(*)&*)((&$*^$&*&$
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,10/13/2026Page
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AMAP
PRACTICE.pdf(*((&#*!(*#*($$(*($(*$Y(&*&$(*)&*)((&$*^$&*&$
BIO
BIO
PRACTICE.pdf(*((&#*!(*#*($$(*($(*$Y(&*&$(*)&*)((&$*^$&*&$
PRACTICE.pdf(*((&#*!(*#*($$(*($(*$Y(&*&$(*)&*)((&$*^$&*&$
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VJyvhjbnoP+_IREOLKDJ(UWRORWUOI
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VJyvhjbnoP+_IREOLKDJ(UWRORWUOI
VJyvhjbnoP+_IREOLKDJ(UWRORWUO
AP Biology Scoring Guide
Unit 3 Test
6. Which of the following best describes the process by which the bacteria are breaking down the glucose to
produce lactic acid?
A The bacteria are breaking down sugars in the absence of oxygen.
B The bacteria are creating a gradient to synthesize more .
C The bacteria are using their mitochondria to break down glucose in the presence of oxygen.
D The bacteria are producing in the Krebs cycle that is then converted into lactic acid.
7. Which of the following was the dependent variable in the researcher’s experiment?
A Time
B
C Glucose concentration
D Lactic acid concentration
8. Which of the following graphs best represents the data in Table 1 ?
Copyright © 2020. The College Board. These materials are part of a College Board program. Use or distribution of these materials online or in print
beyond your school’s participation in the program is prohibited.
Page 4 of 47
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AMAP
BIO
PRACTICE.pdf(*((&#*!(*#*($$(*($(*$Y(&*&$(*)&*)((&$*^$&*&$
BIO
PRACTICE.pdf(*((&#*!(*#*($$(*($(*$Y(&*&$(*)&*)((&$*^$&*&$
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**F VJyvhjbnoP+_IREOLKDJ(UWRORWUOI
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PRACTICE.pdf(*((&#*!(*#*($$(*($(*$Y(&*&$(*)&*)((&$*^$&*&$
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BIO
PRACTICE.pdf(*((&#*!(*#*($$(*($(*$Y(&*&$(*)&*)((&$*^$&*&$
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(&*$**F
**F
VJyvhjbnoP+_IREOLKDJ(UWRORWUOI
VJyvhjbnoP+_IREOLKDJ(UWRORWUO
AP Biology Scoring Guide
Unit 3 Test
1. 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?
The enzyme’s active site binds to and stabilizes the reactant, which decreases the free-energy change of the
A
reaction.
The enzyme’s active site binds to and stabilizes the transition state, which decreases the activation energy of
B
the reaction.
The enzyme’s active site binds to and stabilizes the product, which increases the amount of energy released
C
by the reaction.
The enzyme’s active site binds to and stabilizes both the reactant and the product at the same time, which
D
increases the reaction’s equilibrium constant.
2. Alcohol dehydrogenase ( ) is an enzyme that aids in the decomposition of ethyl alcohol
into nontoxic substances. Methyl alcohol acts as a competitive inhibitor of ethyl alcohol by competing for
the same active site on . When attached to , 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 activity increases.
Competitive inhibition will be terminated because ethyl alcohol will bind to methyl alcohol and decrease
B
activity.
C The peptide bonds in the active site of the enzyme will be denatured, inhibiting the enzyme.
Competitive inhibition will decrease because the proportion of the active sites occupied by substrate will
D
increase.
3. A researcher claims that increased atmospheric carbon dioxide levels cause increased growth rates in plants.
Which of the following statements best supports the researcher’s claim?
Copyright © 2020. The College Board. These materials are part of a College Board program. Use or distribution of these materials online or in print
beyond your school’s participation in the program is prohibited.
Page 1 of 47
Page
Page
1 Page
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of14710/13/2026,
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AMAPAMAPBIO
AMAP
BIO
PRACTICE.pdf(*((&#*!(*#*($$(*($(*$Y(&*&$(*)&*)((&$*^$&*&$
BIO
PRACTICE.pdf(*((&#*!(*#*($$(*($(*$Y(&*&$(*)&*)((&$*^$&*&$
PRACTICE.pdf(*((&#*!(*#*($$(*($(*$Y(&*&$(*)&*)((&$*^$&*&$
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**F VJyvhjbnoP+_IREOLKDJ(UWRORWUOI
,10/13/2026Page
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PRACTICE.pdf(*((&#*!(*#*($$(*($(*$Y(&*&$(*)&*)((&$*^$&*&$
BIO
BIO
PRACTICE.pdf(*((&#*!(*#*($$(*($(*$Y(&*&$(*)&*)((&$*^$&*&$
PRACTICE.pdf(*((&#*!(*#*($$(*($(*$Y(&*&$(*)&*)((&$*^$&*&$
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(&*$
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(&*$**F
**F
VJyvhjbnoP+_IREOLKDJ(UWRORWUOI
VJyvhjbnoP+_IREOLKDJ(UWRORWUO
AP Biology Scoring Guide
Unit 3 Test
Atmospheric carbon dioxide is produced by the burning of fossil fuels, which are formed from the remains of
A
living organisms such as plants.
Atmospheric carbon dioxide is a byproduct of cellular respiration, which is a metabolic process that occurs
B
in plants and other living organisms.
Atmospheric carbon dioxide typically enters plant leaves through stomata, which plants rely on for
C
regulating gas exchange with the atmosphere.
Atmospheric carbon dioxide is the raw material for photosynthesis, which plants rely on for producing
D
sugars and other organic compounds.
4. The figures below illustrate the similarities between ATP synthesis in mitochondria and chloroplasts.
The figures can best assist in answering which of the following questions?
Copyright © 2020. The College Board. These materials are part of a College Board program. Use or distribution of these materials online or in print
beyond your school’s participation in the program is prohibited.
Page 2 of 47
Page
Page
2 Page
of24710/13/2026,
of24710/13/2026,
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AMAPAMAPBIO
AMAP
BIO
PRACTICE.pdf(*((&#*!(*#*($$(*($(*$Y(&*&$(*)&*)((&$*^$&*&$
BIO
PRACTICE.pdf(*((&#*!(*#*($$(*($(*$Y(&*&$(*)&*)((&$*^$&*&$
PRACTICE.pdf(*((&#*!(*#*($$(*($(*$Y(&*&$(*)&*)((&$*^$&*&$
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**F VJyvhjbnoP+_IREOLKDJ(UWRORWUOI
,10/13/2026Page
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AMAP
AMAP
PRACTICE.pdf(*((&#*!(*#*($$(*($(*$Y(&*&$(*)&*)((&$*^$&*&$
BIO
BIO
PRACTICE.pdf(*((&#*!(*#*($$(*($(*$Y(&*&$(*)&*)((&$*^$&*&$
PRACTICE.pdf(*((&#*!(*#*($$(*($(*$Y(&*&$(*)&*)((&$*^$&*&$
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(&*$**F
**F
VJyvhjbnoP+_IREOLKDJ(UWRORWUOI
VJyvhjbnoP+_IREOLKDJ(UWRORWUO
AP Biology Scoring Guide
Unit 3 Test
A Do electron transport chains create a gradient so that ATP synthase can generate ATP molecules?
B What are the sources of energy that drive mitochondrial and chloroplast electron transport systems?
What is the optimal temperature at which ATP synthase chemically converts ADP and a phosphate group
C
into one molecule of ATP?
What is the evolutionary relationship between the ATP synthase in mitochondria and the ATP synthase in
D
chloroplasts?
5. A researcher claims that different metabolic pathways allow bacteria to use different molecules as sources of
matter and energy.
Which of the following statements best helps justify the researcher’s claim by providing a relevant example?
A Rhizobia bacteria form close associations with the roots of bean plants.
B E. coli bacteria reproduce in liquid media containing either glucose or galactose.
C The antibiotic rifampicin inhibits the growth of some bacterial strains but not of others.
D Some viruses that infect bacteria reproduce by either the lysogenic cycle or the lytic cycle.
To investigate bacterial metabolism, a researcher divided a population (culture) of Staphylococcus capitis bacteria
into two sets of culture tubes containing glucose. The researcher added a chemical to one set of tubes and measured
the of the cultures at -minute intervals as the bacteria metabolized the glucose into lactic acid. The data are
shown in Table 1.
TABLE 1. AVERAGE CHANGE IN IN CONTROL AND TREATMENT GROUPS OVER A -MINUTE PERIOD
Average of Control Average of Treatment
Time (min)
( ) ( )
Copyright © 2020. The College Board. These materials are part of a College Board program. Use or distribution of these materials online or in print
beyond your school’s participation in the program is prohibited.
Page 3 of 47
Page
Page
3 Page
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AMAPAMAPBIO
AMAP
BIO
PRACTICE.pdf(*((&#*!(*#*($$(*($(*$Y(&*&$(*)&*)((&$*^$&*&$
BIO
PRACTICE.pdf(*((&#*!(*#*($$(*($(*$Y(&*&$(*)&*)((&$*^$&*&$
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,10/13/2026Page
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AMAP
AMAP
PRACTICE.pdf(*((&#*!(*#*($$(*($(*$Y(&*&$(*)&*)((&$*^$&*&$
BIO
BIO
PRACTICE.pdf(*((&#*!(*#*($$(*($(*$Y(&*&$(*)&*)((&$*^$&*&$
PRACTICE.pdf(*((&#*!(*#*($$(*($(*$Y(&*&$(*)&*)((&$*^$&*&$
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VJyvhjbnoP+_IREOLKDJ(UWRORWUO
AP Biology Scoring Guide
Unit 3 Test
6. Which of the following best describes the process by which the bacteria are breaking down the glucose to
produce lactic acid?
A The bacteria are breaking down sugars in the absence of oxygen.
B The bacteria are creating a gradient to synthesize more .
C The bacteria are using their mitochondria to break down glucose in the presence of oxygen.
D The bacteria are producing in the Krebs cycle that is then converted into lactic acid.
7. Which of the following was the dependent variable in the researcher’s experiment?
A Time
B
C Glucose concentration
D Lactic acid concentration
8. Which of the following graphs best represents the data in Table 1 ?
Copyright © 2020. The College Board. These materials are part of a College Board program. Use or distribution of these materials online or in print
beyond your school’s participation in the program is prohibited.
Page 4 of 47
Page
Page
4 Page
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AMAPAMAPBIO
AMAP
BIO
PRACTICE.pdf(*((&#*!(*#*($$(*($(*$Y(&*&$(*)&*)((&$*^$&*&$
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PRACTICE.pdf(*((&#*!(*#*($$(*($(*$Y(&*&$(*)&*)((&$*^$&*&$
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