AP Biology Unit 1 Test
First and last name
Question 1/34
The diagram below shows how water can adhere to the xylem in the stems of plants, which contributes to water
movement in the plant.
Which of the following best explains how water is able to move upward from the roots of a plant, through its
xylem in the stem, and out to the leaves?
A. Water is polar, and the walls of the xylem are nonpolar. Water molecules have the ability to form
hydrogen bonds with one another but not with the xylem walls.
B. Water is nonpolar, and the walls of the xylem are polar. Water molecules are able to form hydrogen
bonds with the xylem walls, and they are pulled up the xylem.
C. Water and the xylem are both nonpolar. Water molecules have the ability to form hydrogen bonds with
one another but not with the xylem walls.
D. Water and the xylem are both polar. Water molecules have the ability to form hydrogen bonds with each
other and with the walls of the xylem.
Question 2/34
Humans produce sweat as a cooling mechanism to maintain a stable internal temperature. Which of the
following best explains how the properties of water contribute to this physiological process?
A. The high specific heat capacity of water allows the body to absorb a large amount of excess heat energy.
B. The high heat of vaporization of water allows the body to remove excess heat through a phase change of
water from liquid to gas.
C. The high surface tension of water contributes to the physical process by which water leaves the body.
D. The high melting temperature of water allows the body to remove excess heat through a phase change of
water from solid to liquid.
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AP Biology Unit 1 Test
Question 3/34
Water and ammonia interact to form hydrogen bonds, as represented in Figure 1 below.
Figure 1. Water and ammonia interacting
Which statement best helps explain the formation of the hydrogen bond represented in the figure?
A. The oxygen has a partial positive charge, and the nitrogen has a partial negative charge.
B. The nitrogen has a partial negative charge, and the hydrogen attached to the oxygen has a partial positive
charge.
C. The hydrogen attached to the oxygen has a partial negative charge, and the nitrogen also has a partial
negative charge.
D. The nitrogen has a partial positive charge, and the hydrogen attached to the oxygen also has a partial
positive charge.
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AP Biology Unit 1 Test
Question 4/34
Figure 1. below shows water molecules at the air-water interface at the surface of a pond.
Figure 1. Alignment of water molecules at air-water interface
Based on Figure 1, which of the following best describes how the properties of water at an air-water interface
enable an insect to walk on the water's surface?
A. Covalent bonds between water molecules and the air above provide cohesion, which causes tiny bubbles
to form under the feet of the insect.
B. Ionic bonds between molecules at the surface of the water provide an electric charge, which attracts the
feet of the insect, keeping it on the surface.
C. Polar covalent bonds between molecules at the surface of the water provide adhesion, which supports the
weight of the insect.
D. Hydrogen bonds between molecules at the surface of the water provide surface tension, which allows the
water surface to deform but not break under the insect.
Question 5/34
As shown in the diagram below, when environmental temperatures drop below freezing, a layer of ice typically
forms on the surface of bodies of freshwater such as lakes and rivers.
Which of the following best describes how the structure of ice benefits the organisms that live in the water
below?
A. The water molecules in ice are closer together than those in liquid water, so the ice prevents the passage
of air to the water, maintaining a constant gas mixture in the water.
B. The water molecules in ice are closer together than those in liquid water, so the ice forms a barrier that
protects the organisms in the water from the freezing air temperatures.
C. The water molecules in ice are farther apart than those in liquid water, so the ice floats, maintaining the
warmer, denser water at the lake bottom
D. The water molecules in ice are farther apart than those in liquid water, so the ice floats, preventing the
escape of gases from the liquid water.
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AP Biology Unit 1 Test
Question 6/34
Which of the following is most directly responsible for water’s unique properties?
A. It contains oxygen atoms
B. It contains hydrogen atoms
C. It is an ionic compound
D. It forms hydrogen bonds
E. It is nonpolar
Question 7/34
Which of the following is responsible for the cohesive property of water?
A. Hydrogen bonds between the oxygen atoms of two adjacent water molecules
B. Covalent bonds between the hydrogen atoms of two adjacent water molecules
C. Hydrogen bonds between the oxygen atom of one water molecule and a hydrogen atom of another water
molecule
D. Covalent bonds between the oxygen atom of one water molecule and a hydrogen atom of another water
molecule
E. Hydrogen bonds between water molecules and other types of molecules
Question 8/34
A feature of organic compounds NOT found in inorganic compounds is the presence of
A. ionizing chemical groups
B. electrons
C. carbon atoms covalently bonded to each other
D. oxygen
E. hydrogen bonds
Question 9/34
Amylase is an enzyme that converts carbohydrate polymers into monomers. Glycogen synthase is one of the
enzymes involved in converting carbohydrate monomers into polymers.
Which of the following best explains the reactions of these enzymes?
A. Amylase aids in the removal of a water molecule to break covalent bonds whereas glycogen synthase
aids in the addition of a water molecule to form covalent bonds.
B. Amylase aids in the addition of a water molecule to break covalent bonds whereas glycogen synthase
aids in the removal of a water molecule to form covalent bonds.
C. Amylase aids in the addition of a water molecule to form covalent bonds whereas glycogen synthase aids
in the removal of a water molecule to break covalent bonds.
D. Amylase aids in the removal of a water molecule to form covalent bonds whereas glycogen synthase aids
in the addition of a water molecule to break covalent bonds.
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AP Biology Unit 1 Test
Question 10/34
Figure 1 below represents a common process that occurs in organisms.
Which of the following is an accurate description of the process shown in Figure 1 ?
A. The linking of amino acids with an ionic bond as an initial step in the protein synthesis process
B. The formation of a more complex carbohydrate with the covalent bonding of two simple sugars
C. The hydrolysis of amino acids with the breaking of covalent bonds with the release of water
D. The formation of a covalent peptide bond in a dehydration synthesis reaction
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AP Biology Unit 1 Test
Question 11/34
Below shows a formation of the bond shown in Figure 1.
Which of the following best describes the formation of the bond shown above in Figure 1 ?
A. An ionic bond is formed between a carbon atom of one amino acid and the nitrogen atom of the other
amino acid.
B. An ionic bond is formed when the negative charge of a group is balanced by the positive charge of a
hydrogen ion.
C. A covalent bond is formed between a carbon atom and a nitrogen atom along with the formation of H 2O
D. A covalent bond is formed that replaces the hydrogen bond between the group and the atom.
Question 12/34
The synthesis of protein or carbohydrate polymers always produces which of the following as a byproduct?
A. ATP
B. Oxygen
C. Carbon dioxide
D. Urea
E. Water
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AP Biology Unit 1 Test
Question 13/34
Which of the following best describes the structures of carbohydrates?
A. They only occur as disaccharides.
B. They occur as monomers, chains of monomers, and branched structures.
C. They only occur as long and branched structures.
D. They occur as chains of monomers that hydrogen bond with complementary chains of monomers.
Question 14/34
The carbohydrates glucose, galactose, and fructose have the same chemical formula but different structural
formulas, as represented in the structures below.
Which of the following statements about glucose, galactose, and fructose is most likely true?
A. The carbohydrates have the same properties because they have the same number of carbon, hydrogen,
and oxygen atoms.
B. The carbohydrates have the same properties because they each have a single carbon-oxygen double
bond.
C. The carbohydrates have different properties because they have different arrangements of carbon,
hydrogen, and oxygen atoms.
D. The carbohydrates have different properties because they have different numbers of carbon-carbon
bonds.
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AP Biology Unit 1 Test
Question 15/34
Which of the following statements best describes how organisms such as rabbits obtain the carbon necessary for
building biological molecules?
A. Rabbits eat plants and use energy absorbed from the plants to make carbon atoms from electrons,
protons,
and neutrons in the air.
B. Rabbits eat plants and break down plant molecules to obtain carbon and other atoms that they rearrange
into
new carbon-containing molecules.
C. Rabbits eat plants and use water absorbed from the plants to hydrolyze , which the rabbits breathe in
from the air and use as a carbon source.
D. Rabbits eat plants and make carbon-containing molecules by using carbon atoms that the plants absorbed
from the soil and stored in the cells of their leaves.
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AP Biology Unit 1 Test
Question 16/34
Researchers compared similar proteins from related organisms in different habitats. They found that the proteins
from organisms living in harsh environments had a greater number of cysteine amino acids than did proteins
from organisms not living in harsh environments. The structure of cysteine is shown. Bonds can form between
the sulfur atom of different cysteine amino acids ( bonds).
Which of the following best describes the effect of a greater number of cysteine amino acids on the stability of
the proteins?
A. The change has no effect on the stability of the protein because only one type of amino acid is involved.
B. The change leads to increased protein stability because of an increased number of S-S bonds in the
tertiary
structure of the proteins.
C. The change leads to decreased protein stability because of an increased number of S-S bonds in the
tertiary
structure of the proteins.
D. The change leads to increased protein stability only when the added cysteine amino acids are next to
other
cysteine amino acids in the primary structure.
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AP Biology Unit 1 Test
Question 17/34
The molecular structures of linoleic acid and palmitic acid, two naturally occurring substances, are shown in the
figure.
Based on the molecular structures shown in the figure, which molecule is likely to be solid at room temperature?
A. Linoleic acid, because the absence of carbon-carbon double bonds allows the molecules to pack closely
together.
B. Linoleic acid, because the presence of carbon-carbon double bonds prevents the molecules from packing
closely together.
C. Palmitic acid, because the absence of carbon-carbon double bonds allows the molecules to pack closely
together.
D. Palmitic acid, because the presence of carbon-carbon double bonds prevents the molecules from packing
closely together.
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AP Biology Unit 1 Test
Question 18/34
The figure shows a model of the exchange of matter between the organisms that live together in an aquarium.
The model includes matter exchange between plants, fish, and bacteria. The bacteria are represented as
rod-shaped organisms living in the gravel at the bottom of the aquarium.
Which of the following statements best describes how molecules released by the fish become nutrients for the
plants?
A. The carbon dioxide molecules released by the fish are converted by the bacteria to oxygen atoms, which
are
used by the plants to make water molecules.
B. The oxygen molecules released by the fish are converted by the bacteria to ammonia molecules, which
are
used by the plants to make lipids and fatty acids.
C. The nitrites released by the fish are converted by the bacteria to carbon dioxide molecules, which are
used
by the plants to make carbohydrates.
D. The ammonia molecules released by the fish are converted by the bacteria to nitrates, which are used by
the
plants to make proteins and nucleic acids.
Question 19/34
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AP Biology Unit 1 Test
A small protein is composed of 110 amino acids linked together in a chain. As shown in Figure 1, the first and
last five amino acids in the chain are hydrophobic (have nonpolar and uncharged R-groups), whereas the
remaining 100 amino acids are hydrophilic (have charged or polar R-groups). The nature of the R-group
determines if the amino acid is hydrophobic or hydrophilic.
A mutation results in the production of a version of the small protein that is only 105 amino acids long, as shown
in Figure 2. Five of the hydrophobic amino acids are missing from one end of the chain.
Which of the following best depicts the tertiary structures of the two proteins in water? The diagrams in the
options are not drawn to the same scale as those in Figure 1 and Figure 2.
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AP Biology Unit 1 Test
A.
B.
C.
D.
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AP Biology Unit 1 Test
Question 20/34
Which of the following conclusions is most clearly supported by the representations of nucleic acid #1 and
nucleic acid #2?
A. Nucleic acid #1 contains only purines, whereas nucleic acid #2 contains only pyrimidines.
B. Nucleic acid #1 contains the sugar ribose, whereas nucleic acid #2 contains the sugar deoxyribose.
C. Nucleic acid #1 contains positively charged phosphate groups, whereas nucleic acid #2 does not.
D. Nucleic acid #1 contains adenine-thymine base pairs, whereas nucleic acid #2 does not.
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AP Biology Unit 1 Test
Question 21/34
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
substrate to bind.
D. The substitution caused the directionality of the enzyme to change such that the amino terminus of the
normal enzyme has become the carboxyl terminus of the mutated enzyme.
Question 22/34
Students conducted a controlled experiment to investigate whether sawdust provides enough nutrients to support
plant growth. The students separated ten nearly identical sunflower seedlings into two groups. They grew the
seedlings in the first group in potting soil and the seedlings in the second group in sawdust composed mostly of
cellulose. After twenty days, the students recorded observations about the seedlings in each group. The students'
observations are presented in the table below.
The observed differences between the groups most likely resulted from differences in the ability of the seedlings
to produce which of the following monomers?
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AP Biology Unit 1 Test
A.
B.
C.
D.
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AP Biology Unit 1 Test
Question 23/34
The sequences for two short fragments of DNA are shown above. Which of the following is one way in which
these two segments would differ?
A. Segment 1 would not code for mRNA because both strands have T, a base not found in RNA.
B. Segment 1 would be more soluble in water than segment 2 because it has more phosphate groups.
C. Segment 1 would become denatured at a lower temperature than would segment 2 because A-T base
pairs have two hydrogen bonds whereas G-C base pairs have three.
D. Segment 1 must be from a prokaryote because it has predominantly A-T base pairs.
Question 24/34
Which of the following best describes how amino acids affect the tertiary structure of a protein?
A. The number of amino acids determines the tertiary structure of the protein.
B. The interactions of the different R-groups with other R-groups and with their environment determine the
tertiary structure of the protein.
C. The R-group of the last amino acid that is added to a growing polypeptide chain determines the next
amino
acid that is added to the chain.
D. The sequence of the amino acids in the polypeptide chain determines the protein’s primary structure but
has
no effect on its tertiary structure.
Question 25/34
Used to carry the genetic code
A. Proteins
B. Carbohydrates
C. Nucleic acids
D. Lipids
E. Steroids
Question 26/34
Can function as enzymes that catalyze chemical reactions
A. Proteins
B. Carbohydrates
C. Nucleic acids
D. Lipids
E. Steroids
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AP Biology Unit 1 Test
Question 27/34
A student analyzed a viral genome and found that the genome had the following nucleotide composition.
• 28% adenine
• 20% thymine
• 35% cytosine
• 17% guanine
Which of the following best describes the structure of the viral genome?
A. Double-stranded DNA
B. Single-stranded DNA
C. Double-stranded RNA
D. Single-stranded RNA
Question 28/34
The CFTR protein is made up of 1,480 amino acids linked together in a chain. Some humans produce a version
of the CFTR protein in which phenylalanine (an amino acid) has been deleted from position 508 of the amino
acid chain.
Which of the following best predicts how the amino acid deletion will affect the structure of the CFTR protein?
A. It will have no observable effect on the structure of the CFTR protein.
B. It will affect the primary structure of the CFTR protein, but the other levels of protein structure will not
be affected.
C. It will affect the secondary and tertiary structures of the CFTR protein, but the primary structure will not
be affected.
D. It will affect the primary, secondary, and tertiary structures of the CFTR protein.
Question 29/34
Bacteriophages are viruses that infect bacteria. In an experiment, bacteriophages were labeled with either
radioactive phosphorus or radioactive sulfur. The labeled bacteriophages were incubated with bacteria for a brief
amount of time and then removed. The infected bacteria cells were found to contain significant amounts of
radioactive phosphorus but not radioactive sulfur.
Based on the results of the experiment, which of the following types of molecules did the bacteriophages most
likely inject into the bacterial cells?
A. Simple carbohydrate
B. Amino acid
C. DNA
D. Polypeptide
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AP Biology Unit 1 Test
Question 30/34
Figure 1 below represents a nucleic acid fragment that is made up of four nucleotides linked together in a chain.
Figure 1. Nucleic acid fragment
Which of the following characteristics of Figure 1 best shows that the fragment is RNA and not DNA ?
A. The 5' to 3' orientation of the nucleotide chain
B. The identity of each nitrogenous base
C. The charges on the phosphate groups
D. The type of bond linking the nucleotides together
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AP Biology Unit 1 Test
Question 31/34
DNA and RNA are nucleic acids that can store biological information based on the sequence of their nucleotide
monomers. Figure 1 below shows a short segment of each of the two types of nucleic acids.
Figure 1. Nucleic acid segments
Which of the following best describes a structural difference between DNA and RNA?
A. DNA contains four types of nitrogenous bases, whereas RNA contains only two types of nitrogenous
bases.
B. The backbone of DNA contains deoxyribose, whereas the backbone of RNA contains ribose.
C. A DNA molecule is composed of two parallel strands with the same 5' to 3' directionality, whereas an
RNA molecule is composed of only one 5' to 3' strand.
D. Phosphate groups provide rigidity to DNA, but RNA is flexible and contains no phosphate groups.
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AP Biology Unit 1 Test
Question 32/34
Which of the following correctly illustrates a dipeptide and an amino acid in the optimal position to form a
tripeptide?
A.
B.
C.
D.
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AP Biology Unit 1 Test
Question 33/34
FRQ
The diagram shows water molecules as solid ice at 0°Cand as a liquid at 25°C.
(A) Describe why hydrogen bonds form between water molecules.
(B) Explain why the arrangement of water molecules is different in ice and water.
(C) Explain how ice floating on the surface of a body of water affects the water in a way that is beneficial to the
organisms in it.
(descriptive question)
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AP Biology Unit 1 Test
Question 34/34
FRQ
Proteins, large complex molecules, are major building blocks of all living organisms. Below is the structural
form of aprotein.
(A) Describe TWO levels of structure in proteins
(descriptive question)
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