ACS BIOCHEMISTRY Exam 2025 Test
Bank
What are the four major classes of molecules studied in biochemistry (in monomeric
form)? - answers lipids, nucelotides, monosaccharides, amino acids
Polymers of sugars are __________. - answers carbohydrates
Amino acids are the building blocks of _________. - answers proteins
What is the Henderson-Hasselbalch equation? - answers pH = pKa + log([A-]/[HA])
[HA] is the _____________ and [A-] is the ____________. - answers tris acid (HCl), tris
base
Which of the following is the most abundant element in the human body?
A) nitrogen
B) carbon
C) oxygen
D) phosphorous
E) none of the above - answers B) carbon
Which of the major types of biomolecules is never found in a polymeric form?
A) amino acids
B) carbohydrates
C) nucleotides
D) lipids
E) none of the above - answers D) lipids
Which of the following biopolymers is correctly paired with the bond that forms between
the monomers?
A) protein: ester bond
B) polysaccharide: glycosidic bond
C) DNA: phosphate bond
D) RNA: phosphate bondE)all of the above - answers B) polysaccharide: glycosidic
bond
Which of the biopolymers is correctly paired with its major function?
A) protein: information encoding
B) nucleic acids: energy storage
C) lipids: information encoding
D) polysaccharide: energy storage
E) none of the above - answers D) polysaccharide: energy storage
,The similarity of one organism to another (for example a bacteria versus a human) is
most easily done by comparing which biopolymer?
A) nucleic acids
B) polysaccharides
C) proteins
D) lipids
E) all of the above - answers A) nucleic acids
In a water molecule, hydrogens are partially _____; oxygens are partially _____.
A) negative; negative
B) negative; positive
C) positive; positive
D) positive; negative
E) none of the above - answers D) positive; negative
At any given moment, a single water molecule participates in _____ strong hydrogen
bond(s). The role played by the water molecule is best characterized as _____.
A) two ; one H-bond donor, one H-bond acceptor
B) two ; two H-bond donor
C) two ; two H-bond acceptor
D) one; H-bond donor
E) one; H-bond acceptor - answers A) two ; one H-bond donor, one H-bond acceptor
In a hydrogen bond between a water molecule and another biomolecule, _____.
A) a hydrogen ion on the water molecule forms an ionic bond with a hydride ion on the
other molecule
B) the hydrogen bond will typically form between a hydrogen atom and either a nitrogen,
sulfur, or oxygen atom
C) the partial charge on a hydrogen of the water interacts with the partial charge on a
hydrogen of the other molecule
D) a hydrogen on the water molecule forms a covalent bond to an oxygen or nitrogen
atom on the other molecule
E) the hydrogen atom is located between an oxygen atom of the water and a carbon
atom of the other molecule - answers B) the hydrogen bond will typically form between
a hydrogen atom and either a nitrogen, sulfur, or oxygen atom
The strongest non-covalent interactions are _____.
A) van der Waals interactions
B) London dispersion forces
C) hydrogen bonds
D) dipole-dipole interactions
E) ionic interactions - answers E) ionic interactions
Due to the formation of hydrogen bonds, _____ is highly soluble in water.
A) carbon dioxide
B) sodium chloride
,C) methanol
D) octane
E) cholesterol - answers C) methanol
Which of the following explains the interactions that occur between the atoms of water
molecules and the ions that form when sodium chloride dissolves in water?
A) hydrogens interact with the sodium ion, oxygens interact with the chloride ion
B) hydrogens interact with the chloride ion, oxygens interact with the sodium ion
C) hydrogens interact with the sodium ion and the chloride ion
D) oxygens interact with the sodium ion and the chloride ion
E) none of the above - answers B) hydrogens interact with the chloride ion, oxygens
interact with the sodium ion
When a non-polar substance is added to water, how do the molecules of water behave?
A) the regular hydrogen bond pattern is disrupted resulting in a decrease of entropy
B) the regular hydrogen bond pattern is disrupted resulting in an increase of entropy
C) the regular hydrogen bond pattern is disrupted resulting in a decrease of enthalpy
D) the regular hydrogen bond pattern is disrupted resulting in an increase of enthalpy
E) none of the above - answers A) the regular hydrogen bond pattern is disrupted
resulting in a decrease of entropy
Which of the following is an example of the hydrophobic effect?
A) the lipid membrane of cells and organelles
B) protein folding that places hydrophobic amino acids in the interior of the protein
C) the separation of salad dressing
D) oil sheens seen on the ocean following an oil spill
E) all of the above - answers E) all of the above
Which of the following explains the attractive forces between hydrophobic molecules in
an aqueous solution?
A) in an aqueous environment, London dispersion forces between hydrophobic
molecules become stronger
B) in an aqueous environment, London dispersion forces between hydrophobic
molecules and water become stronger
C) since nonpolar molecules do not form hydrogen bonds with hydrogen bonds with
water, they can form hydrogen bonds with other nonpolar molecules
D) there is no increase in attractive forces between nonpolar molecules in an aqueous
environment
E) none of the above - answers D) there is no increase in attractive forces between
nonpolar molecules in an aqueous environment
A molecule that has both a polar and nonpolar region is called _____________.
A) micelleic
B) amphiphilic
C) endergonic
D) a membrane
, E) none of the above - answers B) amphiphilic
Which of the following is an example of an amphipathic molecule?
A) adenine, a base found in nucleic acids
B) glucose, a monosaccharide
C) serine, anamino acid
D) palmitic acid, a fatty acid
E) none of the above - answers D) palmitic acid, a fatty acid
In aqueous solution, globules of up to several thousand amphiphilic molecules arranged
with the hydrophilic groups on the surface and the hydrophobic groups buried in the
center are called _____.
A) micelles
B) vacuoles
C) liposomes
D) bilayers
E) none of the above - answers A) micelles
Which of the following molecules would be prevented from readily crossing a lipid
bilayer?
A) glucose
B) sodium ions
C) potassium ions
D) water
E) all of the above - answers E) all of the above
In an aqueous solution, if the [OH-] is 3.0×10-5M, what is the [H+]?
A) 7.0×10^-9
B) 7.0×10^-2
C) 3.3×10^-3
D) 3.3×10^-10
E) none of the above - answers D) 3.3×10^-10
Which of the following would be the strongest acid?
A) formic acid, pK=3.75
B) succinic acid, a diprotic acid with pK=4.21 and 5.64
C) acetic acid, pK=4.76
D) ammonium ion, pK=9.25
E) cannot be determined from the given information - answers A) formic acid, pK=3.75
What is the pH of a solution that contains three parts of acetic acid and one part sodium
acetate? The pKfor acetic acid is 4.76.
A) 5.24
B) 5.06
C) 4.46
D) 4.28
Bank
What are the four major classes of molecules studied in biochemistry (in monomeric
form)? - answers lipids, nucelotides, monosaccharides, amino acids
Polymers of sugars are __________. - answers carbohydrates
Amino acids are the building blocks of _________. - answers proteins
What is the Henderson-Hasselbalch equation? - answers pH = pKa + log([A-]/[HA])
[HA] is the _____________ and [A-] is the ____________. - answers tris acid (HCl), tris
base
Which of the following is the most abundant element in the human body?
A) nitrogen
B) carbon
C) oxygen
D) phosphorous
E) none of the above - answers B) carbon
Which of the major types of biomolecules is never found in a polymeric form?
A) amino acids
B) carbohydrates
C) nucleotides
D) lipids
E) none of the above - answers D) lipids
Which of the following biopolymers is correctly paired with the bond that forms between
the monomers?
A) protein: ester bond
B) polysaccharide: glycosidic bond
C) DNA: phosphate bond
D) RNA: phosphate bondE)all of the above - answers B) polysaccharide: glycosidic
bond
Which of the biopolymers is correctly paired with its major function?
A) protein: information encoding
B) nucleic acids: energy storage
C) lipids: information encoding
D) polysaccharide: energy storage
E) none of the above - answers D) polysaccharide: energy storage
,The similarity of one organism to another (for example a bacteria versus a human) is
most easily done by comparing which biopolymer?
A) nucleic acids
B) polysaccharides
C) proteins
D) lipids
E) all of the above - answers A) nucleic acids
In a water molecule, hydrogens are partially _____; oxygens are partially _____.
A) negative; negative
B) negative; positive
C) positive; positive
D) positive; negative
E) none of the above - answers D) positive; negative
At any given moment, a single water molecule participates in _____ strong hydrogen
bond(s). The role played by the water molecule is best characterized as _____.
A) two ; one H-bond donor, one H-bond acceptor
B) two ; two H-bond donor
C) two ; two H-bond acceptor
D) one; H-bond donor
E) one; H-bond acceptor - answers A) two ; one H-bond donor, one H-bond acceptor
In a hydrogen bond between a water molecule and another biomolecule, _____.
A) a hydrogen ion on the water molecule forms an ionic bond with a hydride ion on the
other molecule
B) the hydrogen bond will typically form between a hydrogen atom and either a nitrogen,
sulfur, or oxygen atom
C) the partial charge on a hydrogen of the water interacts with the partial charge on a
hydrogen of the other molecule
D) a hydrogen on the water molecule forms a covalent bond to an oxygen or nitrogen
atom on the other molecule
E) the hydrogen atom is located between an oxygen atom of the water and a carbon
atom of the other molecule - answers B) the hydrogen bond will typically form between
a hydrogen atom and either a nitrogen, sulfur, or oxygen atom
The strongest non-covalent interactions are _____.
A) van der Waals interactions
B) London dispersion forces
C) hydrogen bonds
D) dipole-dipole interactions
E) ionic interactions - answers E) ionic interactions
Due to the formation of hydrogen bonds, _____ is highly soluble in water.
A) carbon dioxide
B) sodium chloride
,C) methanol
D) octane
E) cholesterol - answers C) methanol
Which of the following explains the interactions that occur between the atoms of water
molecules and the ions that form when sodium chloride dissolves in water?
A) hydrogens interact with the sodium ion, oxygens interact with the chloride ion
B) hydrogens interact with the chloride ion, oxygens interact with the sodium ion
C) hydrogens interact with the sodium ion and the chloride ion
D) oxygens interact with the sodium ion and the chloride ion
E) none of the above - answers B) hydrogens interact with the chloride ion, oxygens
interact with the sodium ion
When a non-polar substance is added to water, how do the molecules of water behave?
A) the regular hydrogen bond pattern is disrupted resulting in a decrease of entropy
B) the regular hydrogen bond pattern is disrupted resulting in an increase of entropy
C) the regular hydrogen bond pattern is disrupted resulting in a decrease of enthalpy
D) the regular hydrogen bond pattern is disrupted resulting in an increase of enthalpy
E) none of the above - answers A) the regular hydrogen bond pattern is disrupted
resulting in a decrease of entropy
Which of the following is an example of the hydrophobic effect?
A) the lipid membrane of cells and organelles
B) protein folding that places hydrophobic amino acids in the interior of the protein
C) the separation of salad dressing
D) oil sheens seen on the ocean following an oil spill
E) all of the above - answers E) all of the above
Which of the following explains the attractive forces between hydrophobic molecules in
an aqueous solution?
A) in an aqueous environment, London dispersion forces between hydrophobic
molecules become stronger
B) in an aqueous environment, London dispersion forces between hydrophobic
molecules and water become stronger
C) since nonpolar molecules do not form hydrogen bonds with hydrogen bonds with
water, they can form hydrogen bonds with other nonpolar molecules
D) there is no increase in attractive forces between nonpolar molecules in an aqueous
environment
E) none of the above - answers D) there is no increase in attractive forces between
nonpolar molecules in an aqueous environment
A molecule that has both a polar and nonpolar region is called _____________.
A) micelleic
B) amphiphilic
C) endergonic
D) a membrane
, E) none of the above - answers B) amphiphilic
Which of the following is an example of an amphipathic molecule?
A) adenine, a base found in nucleic acids
B) glucose, a monosaccharide
C) serine, anamino acid
D) palmitic acid, a fatty acid
E) none of the above - answers D) palmitic acid, a fatty acid
In aqueous solution, globules of up to several thousand amphiphilic molecules arranged
with the hydrophilic groups on the surface and the hydrophobic groups buried in the
center are called _____.
A) micelles
B) vacuoles
C) liposomes
D) bilayers
E) none of the above - answers A) micelles
Which of the following molecules would be prevented from readily crossing a lipid
bilayer?
A) glucose
B) sodium ions
C) potassium ions
D) water
E) all of the above - answers E) all of the above
In an aqueous solution, if the [OH-] is 3.0×10-5M, what is the [H+]?
A) 7.0×10^-9
B) 7.0×10^-2
C) 3.3×10^-3
D) 3.3×10^-10
E) none of the above - answers D) 3.3×10^-10
Which of the following would be the strongest acid?
A) formic acid, pK=3.75
B) succinic acid, a diprotic acid with pK=4.21 and 5.64
C) acetic acid, pK=4.76
D) ammonium ion, pK=9.25
E) cannot be determined from the given information - answers A) formic acid, pK=3.75
What is the pH of a solution that contains three parts of acetic acid and one part sodium
acetate? The pKfor acetic acid is 4.76.
A) 5.24
B) 5.06
C) 4.46
D) 4.28
