Antioxidants are believed to:

cause cancer.
destroy free radicals.
break down vitamins.
break down hydrogen peroxide.
generate free radicals.

destroy free radicals.

An enzyme that breaks down the superoxide radical (O₂ ^-) is:

catalase.
hydrogen peroxide.
superoxide dismutase.
vitamin C.
glutathione.

superoxide dismutase.

Atoms that have the same number of protons, but different numbers of neutrons are said to be __________ of one another.

isotropes
isomers
isotopes
isotonics
serotopes

isotopes

The term ________ refers to atoms that differ in the number of protons and neutrons in their nuclei.

nuclide
nucleoid
isotroid
nucloid
isoclide

nuclide

Radioisotopes or radionuclides:

contain unstable combinations of protons and electrons.
break apart or disintegrate in order to achieve a more unstable configuration.
can absorb particles or electromagnetic radiation.
contain an unstable combination of protons and neutrons.
pick up neutrons in order to achieve a more stable configuration.

contain an unstable combination of protons and neutrons

Which form of radiation emitted by a radioactive isotope consists of electromagnetic radiation or photons?

alpha particles
beta radiation
gamma radiation
X-rays
all of the answers

gamma radiation

What is the name of a medical therapy in which patients are exposed to beams of radiation emitted by chunks of ⁶⁰Co arranged around in a hemisphere around a patient’s head? The beams are aimed to converge on a single point in three dimensions, allowing the precise targeting of a tumor deep inside the brain.

the radioincision technique
the gamma knife technique
radiosurgery
beta radiation infusion
gamma localization therapy

the gamma knife technique

Polar molecules are __________; nonpolar molecules are __________.

hydrophilic; hydrophilic
hydrophobic; hydrophobic
hydrophilic; hydrophobic
hydrophobic; hydrophilic
hydrophilic; either hydrophilic or hydrophobic

hydrophilic; hydrophobic

Which of the following characteristics does NOT apply to water?

The water molecule is asymmetric.
The water molecule readily forms hydrophobic interactions.
The covalent bonds in water are strongly polarized.
All three atoms in the water molecule readily form hydrogen bonds.
Water is an excellent solvent.

The water molecule readily forms hydrophobic interactions.

Weak attractions between adjacent water molecules are:

hydrogen bonds.
polar covalent bonds.
van der Waals forces.
ionic bonds.
hydrophobic interactions.

hydrogen bonds.

A weak attractive force between two molecules with transitory dipoles that are very close to one another and oriented in an appropriate manner is called:

a hydrogen bond.
a hydrophobic interaction.
a nonpolar covalent bond.
an ionic bond.
a van der Waals force.

a van der Waals force.

The function of a buffer is to:

generate slight changes in pH.
maintain stable pH.
create a neutral pH.

maintain stable pH.

Cytoplasm has a pH of about 7. What is the concentration, in moles/liter, of the hydrogen ion?

7
7 x 10^-7
1 x 10^-7
1 x 10⁷
7 x 10^-1

1 x 10^-7

As a solution becomes more acidic:

H⁺ concentration increases.
H⁺ concentration decreases.
pH increases.
pH decreases.
H⁺ concentration increases and pH decreases.

H⁺ concentration increases and pH decreases.

The major cellular macromolecules include:

proteins, lipids, amino acids, and polysaccharides.
proteins, amino acids, lipids, and nucleic acids.
proteins, nucleic acids, polysaccharides, and antibodies.
proteins, nucleic acids, polysaccharides, and lipids.
proteins, steroids, polysaccharides, and nucleic acids.

proteins, nucleic acids, polysaccharides, and lipids.

How many electrons are in the outer shell of a carbon atom?

one
two
three
four
eight

four

_______________ are particular groupings of atoms that often behave as a unit and give organic molecules their physical properties, chemical reactivity, and solubility in aqueous solution.

Functional groups
Proteins
Metabolic intermediates
Polymers
Hydrocarbons

Functional Groups

Which of the following statements about functional groups is FALSE?

Most functional groups contain one or more electropositive atoms (N, P, O, and/or S).
Most functional groups make organic molecules more polar.
Most functional groups make organic molecules more water soluble.
Most functional groups make organic molecules more reactive.
Several functional groups can ionize and become positively or negatively charged.

Most functional groups contain one or more electropositive atoms (N, P, O, and/or S).

Which of the following groups of macromolecules contains ONLY polymers?

proteins, lipids, polysaccharides
proteins, nucleic acids, lipids
proteins, nucleic acids, polysaccharides
lipids, nucleic acids, polysaccharides
lipids, proteins, polysaccharides, nucleic acids

proteins, nucleic acids, polysaccharides

Cellular molecules have complex chemical structures and must be synthesized in a step-by-step sequence beginning with specific starting materials. Each series of chemical reactions in the cell is called a:

chemical pathway.
degradation pathway.
synthetic pathway.
metabolic pathway.
meditative pathway.

metabolic pathway.

What is the name of the process by which plants harvest carbon from the CO₂ in the air?

carbonization
carbon fixation
carbon ossification
carbon respiration
carbon fixability

carbon fixation

How do some plants fix nitrogen out of the air?

They simply attach gaseous nitrogen to already existing carbon skeletons in the chloroplasts.
They rely on symbiotic protists, which are able to fix nitrogen out of the air.
They rely on rhizobia, which are able to fix nitrogen out of the air.
They rely on symbiotic viruses, which are able to fix nitrogen out of the air.
They rely on symbiotic bacteria, called rhizobia, which are able to fix nitrogen out of the air.

They rely on symbiotic bacteria, called rhizobia, which are able to fix nitrogen out of the air.

Rhizobia grow on the roots of legumes in structures called _________; they invade plant cells and live inside them in specialized membrane compartments called:

bacteroids, root nodules.
root nodules, nodulary structures.
root nodules, bacteroids.
root nodules, rhizobosomes.
nodulary structures, rhizobosomes.

root nodules, bacteroids.

The rhizobia bacteria convert nitrogen from the air directly into what substance?

ammonia
acetic acid
aminopterin
proteins
nitrate

ammonia

When leguminous plants die or are harvested, the amino acids left behind in the dead plant parts end up in the soil, where they degrade, producing nitrate. The nitrate can be used by other plants, usually non-leguminous plants, as a nitrogen source. This process is a farming process known as:

crop leguminization.
no-till cultivation.
crop rotation.
crop sensitization.
nitrogenous utilization.

crop rotation.

From where does the phosphorus that plants need in the soil normally come?

the air
other plants
the air and other plants
the ground, where it is a component of rocks and minerals and leaches into ground water
from insects that live in the soil and have symbiotic relationships to the plants

the ground, where it is a component of rocks and minerals and leaches into ground water

Prions:

are a type of virus.
are a type of infectious agent composed only of protein.
are a treatment for CJD developed by Stanley Prusiner.
cause Alzheimer's disease.
destroy the cells lining the gastrointestinal tract.

are a type of infectious agent composed only of protein.

Which of the following was the first protein whose tertiary structure was determined?

hemoglobin
insulin
myoglobin
collagen
actin

myoglobin

The scientist who elucidated the three-dimensional structure of hemoglobin is:

Max Perutz.
John Kendrew.
Frederick Sanger.
Linus Pauling.
Robert Corey.

Max Perutz.

Molecular chaperones were originally referred to as:

chaperonins.
heat shock proteins.
Rubisco.
GroEL.
Hsp60.

heat shock proteins.

The first protein to have its amino acid sequence determined was:

hemoglobin.
beef insulin.
spider silk.
myoglobin.
keratin.

beef insulin.

Study of the proteome of a cell:

requires use of a computer to compare fingerprints of extracted proteins to those of known proteins.
is furthered by mass spectrometry that provides a pattern characteristic of individual proteins.
is based on knowledge of the genome of a cell.
can reveal changes in protein composition within a cell over time.
all of these statements are true.

all of these statements are true.

Molecular chaperones:

are carbohydrates that attach to specific amino acids.
may prevent growing proteins from making random, nonselective interactions with other proteins in various cellular compartments.
direct proteins out of the nucleus and into the cytoplasm.
direct proteins out of the cell through the plasma membrane.
all of these choices are true of molecular chaperones.

may prevent growing proteins from making random, nonselective interactions with other proteins in various cellular compartments.

Which one of the following statements is FALSE?

Proteins are biochemical adaptations that are subject to evolutionary change.
Proteins with identical sequences of amino acids must also have identical folding patterns, even when interacting with different substances.
Small changes in amino acid sequence may have dramatic effects on protein shape.
The greater the evolutionary distance between two organisms, the greater the difference in the amino acid sequences of their proteins.
Genes that encode members of a protein family are thought to have arisen from a single ancestral gene.
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Proteins with identical sequences of amino acids must also have identical folding patterns, even when interacting with different substances.

Distinct regions of a protein that fold independently of one another and often function in a semi-independent manner are called:

domains.
side chains.
amino acids.
alpha ( α ) helices.
hydrophobic.

domains

The variability among polypeptides is primarily due to:

the length of the polypeptide chain.
noncovalent interactions within the molecule.
the diverse side chains on the different amino acids.
addition of a phosphate group.
the addition of sulfate groups to some amino acids.

the diverse side chains on the different amino acids.

Which statement(s) are FALSE regarding site-directed mutagenesis?

It alters a DNA sequence to produce a specific change in a translated protein.
It can be used to determine the role of a particular residue in the folding or function of a polypeptide.
It does not result in a change in the structure of a protein.
It can be used to produce clinically useful proteins.
It requires codon alteration.

It does not result in a change in the structure of a protein.

Which of the following is a pyrimidine found only in RNA?

adenine
uracil
thymine
glycine
cytosine

uracil

The study of proteins using siRNAs is MOST useful in determining:

protein structure.
protein denaturation.
changes in protein composition within the cell over time.
the DNA sequence that codes for a protein.
the function of a protein.

the function of a protein.

The specific linear sequence of amino acids that constitutes a polypeptide chain is its:

primary structure.
secondary structure.
tertiary structure.
quaternary structure.
DNA sequence.

primary structure.

Because they both associate with proteins that assist in the assembly of their subunits, Rubisco is MOST similar to:

antibody molecules.
heat shock proteins.
BiP.
GroES.
green fluorescent protein (GFP).
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antibody molecules.

The tertiary structure of a protein is stabilized by:

hydrogen bonds between the atoms that form the peptide bonds of the backbone
noncovalent interactions between side chains of amino acids.
peptide bonds between amino and carboxyl groups on adjacent amino acids.
an aqueous environment.
addition of methyl groups.

noncovalent interactions between side chains of amino acids.

The process of predicting the tertiary structure of an unknown protein by aligning its amino acids onto the corresponding amino acids of a protein whose structure is already known is called:

denaturation.
x-ray crystallography.
chaperoning.
threading.
self-assembly.

threading.

The drug Gleevec is useful in the treatment of:

diabetes.
acromegaly.
chronic myelogenous leukemia.
influenza.
heart disease.

chronic myelogenous leukemia.

Disulfide bridges can form between two residues of:

cysteine.
glycine.
proline.
histidine.
arginine.

cysteine.

The human genome contains:

1,000 to 2,000 genes.
10,000 to 12,000 genes.
20,000 to 22,000 genes.
100,000 to 120,000 genes.
it's impossible to determine.

20,000 to 22,000 genes.

Spongiform encephalopathy describes all of the following diseases EXCEPT:

Kuru.
Mad cow disease.
Creutzfeld-Jakob disease.
Alzheimer's disease.
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Alzheimer's disease.

Silk is composed of a protein containing a large amount of:

alpha (α) helix conformations.
disulfide bridges.
proline.
beta (β) sheet conformations.
quaternary structure.

beta (β) sheet conformations.

Ribosomal RNA:

acts as a ribozyme during protein synthesis.
is a double-stranded helix.
carries the genetic message that is translated at the ribosome.
retrieves amino acids and brings them to the ribosome for incorporation into a growing protein.
does not have double-stranded segments and complex three-dimensional structures.

acts as a ribozyme during protein synthesis.

Different versions of a protein, which are known as ________, are adapted to function in different tissues or at different stages of development.

mutations
isoforms
families
subunits
homologous

isoforms

Saturated fatty acids lack which of the following?

single bonds between carbon atoms
a glycerol molecule
a hydrocarbon chain
double bonds between carbon atoms
energy

double bonds between carbon atoms

Denaturation of a protein:

is the mechanism by which stabilization of the protein structure is achieved.
can be caused by detergents, organic solvents, heat, certain chemical compounds, or radiation.
interferes with covalent bonding that stabilizes the protein's tertiary structure.
does not result in loss of function of the protein.
occurs at very low temperatures.

can be caused by detergents, organic solvents, heat, certain chemical compounds, or radiation.

Hemoglobin A1c can be measured in blood tests to track the progress of which disease?

heart disease
liver disease
kidney disease
diabetes
anorexia

diabetes

The liver stores energy in the form of a polysaccharide called:

starch.
glycogen.
fiber.
cellulose.
glucose.

glycogen.

A shortage of cholesterol in the body could interfere with the formation of:

progesterone.
testosterone.
cell membranes.
estrogen.
all of the choices are correct.

all of the choices are correct.

Which one of the following polysaccharides CANNOT be digested by humans?

glucose
glycogen
cellulose
starch
amylose

cellulose

Strategies to develop medications to battle Alzheimer's disease have included:

antibiotics that prevent replication of prions.
procedures that encourage the formation of the Ab42 peptide.
removal of the Ab42 peptide or the amyloid deposits that it produces.
fostering interaction between Aβ molecules to generate fibrillar aggregates.
infecting transgenic mice with prions.

removal of the Ab42 peptide or the amyloid deposits that it produces.

Which of the following are needed to form a triacylglycerol molecule?

3 glycerol molecules
3 fatty acid molecules
3 carbon rings
3 phosphate groups
3 trans fats

3 fatty acid molecules

In a polypeptide, when peptide bonds are formed between adjacent amino acids:

a water molecule is gained by the carboxyl group.
the carboxyl group of one amino acid joins with the amino group of the adjacent amino acid, and water is lost.
the amino groups of two adjacent amino acids are attracted by hydrogen bonds.
the carboxyl groups of two adjacent amino acids are joined by a covalent bond.
the protein folds into a complex shape.
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the carboxyl group of one amino acid joins with the amino group of the adjacent amino acid, and water is lost.

How many polypeptide chains comprise a hemoglobin molecule?

one
two
three
four
two or four

four

The glucose monomers of amylose are connected by what type of linkages?

α (1 → > 6) linkages
α (1 → > 4) linkages
β (1 → > 6) linkages
β (1 → > 4) linkages
α (4 → > 1) linkages

α (1 → > 4) linkages

The glucose monomers of cellulose are connected by what type of linkages?

α (1 → > 6) linkages
α (1 → > 4) linkages
β (1 → > 6) linkages
β (1 → > 4) linkages
α (4 → > 1) linkages

β (1 → > 4) linkages

What polysaccharide is found in the outer coverings of invertebrates, like insects, spiders, and crustaceans?

glycogen
amylose
cellulose
amylopectin
chitin

chitin

Molecules having both hydrophobic and hydrophilic regions are said to be:

amphipathic.
amphoteric.
ambidextrous.
amphibian.

amphipathic.

Which of the following molecules is found in cell membranes?

triacylglycerol
phospholipids
cholesterol
proteins
phospholipids, cholesterol, and proteins

phospholipids, cholesterol, and proteins

Which amino acid has a charge of +1?

valine
glutamic acid
lysine
serine
glutamine

lysine

Which amino acid is a polar uncharged amino acid?

arginine
phenylalanine
leucine
glycine
tyrosine

tyrosine

Which amino acid is a nonpolar amino acid?

glutamine
aspartic acid
threonine
methionine
cysteine

methionine

How do amino acids like acetylated lysine and phospohotyrosine, which are not among the 20 amino acids that are inserted into proteins, get into proteins?

They are inserted directly.
They are the result of the alteration of R groups of the 20 amino acids after their incorporation into the polypeptide.
They are the result of the alteration of R groups of the 20 amino acids before their incorporation into the polypeptide.
There really are more than 20 amino acids that are inserted into proteins.
Their atoms are altered by insertion into the polypeptide.

They are the result of the alteration of R groups of the 20 amino acids after their incorporation into the polypeptide.

Which amino acid is most likely to be found in the core of a protein?

methionine
asparagine
serine
threonine
glutamic acid

methionine

Which of the following tripeptides would be most likely to be soluble in an organic (hydrophobic) solvent like benzene?

N - phenylalanine - alanine - glycine – C
N - leucine - alanine - lysine - C
N - proline - phenylalanine - leucine - C
N - arginine - lysine - proline - C
N - glutamate - aspartate - glycine – C

N - proline - phenylalanine - leucine - C

What bond is responsible for the branch points in glycogen?
α (1 → >4) glycosidic linkages
β (1 → >4) glycosidic linkages
α (1 → >6) glycosidic linkages
β (1 → >6) glycosidic linkages
3'-5' phosphodiester linkages

α (1 → >6) glycosidic linkages

The b -pleated sheet is characterized by orientation of ______ the molecular axis.

H bonds parallel to
H bonds perpendicular to
ionic bonds parallel to
ionic bonds perpendicular to
peptide bonds perpendicular to

H bonds perpendicular to

Which of the following is a nucleotide?

phosphate + ribose
adenine + deoxyribose
sugar + nitrogenous base
adenine + ribose + phosphate
guanine + phosphate

adenine + ribose + phosphate

Self-assembly of complex molecular structures was first convincingly demonstrated in studies of:

ribosomes.
tobacco mosaic virus.
molecular chaperones.
hemoglobin.
cytoskeleton.

tobacco mosaic virus.

The scientist who first succeeded in reconstituting complete, fully functional 30S bacterial ribosomal subunits was:

Linus Pauling.
Heinz Fraenkel-Conrat.
Stanley Prusiner.
Masayasu Nomura.
Max Perutz.

Masayasu Nomura.