Biology 150

How many experiments have been conducted worldwide to test Darwin’s initial hypothesis regarding natural selection?

Thousands

True or false: A tentative explanation based on observation is referred to as a hypothesis.

True

A single experiment or observation can ____________ a hypothesis.

Reject or Support

Which one of the following statements about hypotheses is incorrect?
1. Hypotheses can be tested by experiments or by making additional observations.
2. Hypotheses that provide reasonable explanations do not need to be tested.
3. Hypotheses make predictions about observations not yet made.
4. A collection of related hypotheses that endures repeated testing is called a theory.
5. All of the above statements about hypotheses are correct.

2

The strongest evidence that a meteor impact is responsible for dinosaurs becoming extinct is provided by:
1. none of the above; no evidence supports a meteor impact being responsible for the extinction of the dinosaurs
2. contamination of fossils from that time period with fragments of rock that penetrated the skeletons of many dinosaurs
3. the presence of significant levels of iridium in the rock layers corresponding to the time of dinosaur extinction
4. high levels of particulate matter in the lungs of dinosaur specimens perfectly preserved in ice
5. the detection of high levels of radioactivity in the fossilized remains of dinosaurs from the time period corresponding to extinction

3

True or false: Because water is so abundant on Earth, oxygen and hydrogen make up a majority of the known matter of the universe.

False

True or false: Living systems differ from non-living systems in that energy not used to do work is lost as heat, reducing the total amount of energy in the universe.

False

Which one of the following elements is found in non-living systems but not found in more than trace amounts in living systems?
silicon
oxygen
carbon
hydrogen
calcium

silicon

In Pasteur’s experiment showing that living organisms arise from other living organisms, which one of the following statements most accurately describes Pasteur’s hypothesis?
1. Straight-neck flasks allow for more contamination than swan-neck flasks.
2. Sterilization of broth kills microbes.
3. If microbes arise from non-living matter, they should appear spontaneously in sterile broth.
4. The first cells must have come from chemical reactions occurring in early Earth.
5. Microbes should be capable of growing equally well in sterile broth contained in both straight-neck and swan-neck flasks.

3

True or false: Organisms from all classifications of life are composed of cells.

True

True or false: There are many different types of bacteria known to be able to grow in a human host, and they are all disease-causing organisms.

False

With humans making up such a small percentage of life on Earth, which of the following represents the rationale behind spending a disproportionate amount of scientific research studying humans?
1. Our role in the ecosystem needs to be understood in order to plan for our future.
2. All of the above are reasons for spending a disproportionate amount of scientific research studying humans.
3. Humans are interested in learning how their own bodies function.
4. The more that is discovered about humans, the more likely it is that disease can be combatted.
5. Humans are curious about their origins.

2

The atom:
1. has negatively charged particles circling around a positively charged nucleus.
2. is the unit of composition for elements.
3. contains protons, neutrons, and electrons.
4. is the basic unit of matter.
5. All of these statements about atoms are correct.

5

The designation of magnesium ion as Mg2+ indicates:
1. an atom that has lost two electrons and is negatively charged.
2. an atom that has lost two electrons and is positively charged.
3. an atom that has gained two protons and is positively charged.
4. an atom that has gained two protons and is negatively charged.
5. an atom that has two more neutrons than protons.

2

Using the periodic table in Figure 2.3, determine which one of the following elements would be found in least abundance in a living cell.

hydrogen (H)
zinc (Zn)
sodium (Na)
silicon (Si)
phosphorous (P)

Si

Which one of the following elements is found in every organic molecule?

nitrogen
oxygen
carbon
sulfur
hydrogen

Carbon

True or false: an ionic interaction, such as the interaction between Na+ and Cl-, is considered a covalent bond.

False

As part of their normal function, many proteins bind to DNA briefly and then release it again. Which types of bonds might be involved in these transient protein-DNA interactions? Check all answers that apply.

hydrogen
ionic
covalent
van der Waals forces

All, but covalent

What important feature(s) of noncovalent bonds makes them so important to life?
1. They are strong bonds that hold atoms together tightly in cells.
2. They are weak in a cellular environment so they can be made, broken, and reformed easily.
3. They can only occur in cells.
4. Options 1 and 3.
5. Options 2 and 3.

2

Which of the following most accurately describes a polar covalent bond?
1. the interaction of a hydrogen connected to an atom with a high electronegativity, and an electronegative atom of another molecule
2. the interaction of an atom with very high electronegativity and an atom with very low electronegativity
3. the unequal sharing of electrons between an atom with a partial positive charge and an atom with a partial negative charge
4. the equal sharing of electrons between atoms of identical or similar electronegativities
5. None of these choices accurately describe polar covalent bonds.

3

In an atom that is NOT an ion, which of the following must be true?
1. The number of electrons equals the number of protons.
2. The number of electrons equals the number of neutrons.
3. The number of protons equals the number of neutrons.

1

Which of the following correctly pairs the particles of an atom with their physical properties?
1. Proton-positively charged; neutron-uncharged; electron-negatively charged
2. Proton-negatively charged; neutron-uncharged; electron-positively charged
3. Proton-positively charged; neutron-negatively charged; electron-uncharged

1

The ability of atoms to attract electrons is referred to as:

Electronegativity

Sometimes atoms gain or lose particles. The loss of which of the following would result in a change of overall electrical charge?

protons or electrons
protons only
electrons only
neutron only
protons or neutrons
neutrons or electrons

Protons or Electrons

Molecules made primarily of carbon and hydrogen are called hydrocarbons. How many hydrogen atoms are present in the following molecule?

A hydrocarbon chain of five carbons joined to each other by single covalent bonds.

6
8
10
12

12

A pair of shared valence electrons is referred to as a(n):

ionic bond.
hydrogen bond.
van der Waals interaction.
covalent bond.
hydrophobic effect.

Covalent Bond

Which one of the following represents the pH of a solution with the highest concentration of hydrogen ions?

1.0
4.5
7.0
9.1
11.5

1.0

A phosphodiester bond is formed between:

a fatty acid and a glycerol molecule.
two amino acids.
a base and a sugar.
a 3′ phosphate and a 5′ hydroxyl group.
a 5′ phosphate and a 3′ hydroxyl group.

5′ phosphate and 3′ hydroxyl group

Which of the following most accurately describes a polar covalent bond?
1. the interaction of a hydrogen connected to an atom with a high electronegativity, and an electronegative atom of another molecule
2. the interaction of an atom with very high electronegativity and an atom with very low electronegativity
3. the unequal sharing of electrons between an atom with a partial positive charge and an atom with a partial negative charge
4. the equal sharing of electrons between atoms of identical or similar electronegativities
5. None of these choices accurately describe polar covalent bonds.

3

Which of the following statements about water is correct?
1. Water is the most abundant molecule in living cells.
2. Water is a polar molecule.
3. Water has good solvent properties.
4. Water can drive biological processes such as the formation of cell membranes.
5. All of these statements about water are correct.

5

Several chemical properties make water uniquely suited for its role as a central "molecule of life." Which of the following is FALSE?
1. Hydrogen bonding leads to high cohesiveness between water molecules.
2. Water resists temperature changes.
3. Water is always polar.
4. The structure of a water molecule is stabilized by hydrogen bonds.
5. Water is a good solvent of polar molecules and ions.

4

Imagine you were there when Stanley Miller carried out his experiment about the building blocks of life. If Miller originally identified five different amino acids, how many polypeptides that are 10 amino acids long could be made from just these five amino acids?
5 x 10 = 50
10^5 = 100,000
5^10 = 9,765,625
Cannot be determined

5^10

What is the chemical basis for water’s role as the universal solvent?
1. Because water is polar, it disrupts most covalent bonds.
2. Because water is polar, it disrupts other hydrogen bonds.
3. Because water is polar, it disrupts ionic bonds.
4. Options 1 and 2.
5. Options 2 and 3.

5

Which of the following components of an amino acid differs from one amino acid to another?

the α-carbon
the carboxyl group
the side chain
the amino group
the hydrogen opposite the R-group

The Side Chain

The linkage of one amino acid to another amino acid in a protein is most accurately referred to as a(n):

peptide bond.
glycosidic bond.
ionic bond.
R-group.
phosphodiester bond.

Peptide Bond

Consider the structure and function of DNA. Which of the following statements is true?
1. Because DNA contains carbohydrates, it provides structural support to the cells.
2. The phosphodiester bonds that stabilize the association of the two strands are easily broken and reformed.
3. If the sequence of one DNA strand is known, then the sequence of the other strand can be determined.
4. Since DNA is made of phosphate groups that are ionized, it could easily pass through a cell membrane.

3

If you isolate a single nucleotide from a nucleic acid chain and determine that the nitrogenous ring structure is cytosine, you could say with certainty that the nucleotide could have come from:

neither DNA nor RNA.
either DNA or RNA.
DNA but not RNA.
double-stranded DNA but not single-stranded DNA.
RNA but not DNA.

Either

True or false: although monosaccharides can exist in linear form, virtually all cellular monosaccharides are found in circular form.

True

Which one of the following types of fatty acids would be likely to have the lowest melting temperature?

long tails and high saturation
short tails and high saturation
long tails and low saturation
short tails and low saturation
All fatty acids have the same melting temperature regardless of tail length or level of saturation.

Short tails and low saturation

Which of the following are covalent bonds?

glycosidic bonds
phosphodiester bonds
All of the above
peptide bonds

All

Cells change the composition of their plasma membranes as a response to changing environments. In general, colder temperatures reduce the fluidity of the membrane, so cells will produce different molecules to bring the fluidity back to normal. How would the cell change the membrane in response to colder temperatures?

increase the amount of unsaturated fatty acids
increase the length of the fatty acid side chains in the phospholipids
increase the amount of saturated triacylglycerols

Increase amount of unsaturated fatty acids

Consider the structure and function of DNA. Which of the following statements is true?
1. Since DNA is made of phosphate groups that are ionized, it could easily pass through a cell membrane.
2. The phosphodiester bonds that stabilize the association of the two strands are easily broken and reformed.
3. If the sequence of one DNA strand is known, then the sequence of the other strand can be determined.
4. Because DNA contains carbohydrates, it provides structural support to the cells.

3

The structural diversity of carbon-based molecules is based upon which of the following properties?

None of these choices is correct.
All of these choices are correct.
the ability of those bonds to rotate freely
the orientation of those bonds in the form of a tetrahedron
the ability of carbon to form four covalent bonds

All

Which of the following is true of DNA?
1. The nucleotides in one strand are connected by hydrogen bonds.
2. A phosphate group in a nucleotide is attached to the 3′ carbon in ribose.
3. A purine always forms a complementary base pair with a pyrimidine.
4. The percentage of the purine A always equals the percentage of the purine G.
5. It is used by ribosomes for translation.

3

In a nucleotide, the phosphate is attached to the ____________ carbon of the sugar, and the base is attached to the ____________ carbon of the sugar.

1′; 5′
2′; 3′
3′; 5′
5′; 1′
5′; 3′

5′:1′

Using Chargaff’s rules, you can determine that the DNA of an organism that contains 30% adenine would contain ____________ guanine.

20%
30%
40%
60%
70%

20%

Deoxyribonucleic acid is used for: (choose all that apply)

transmission of information.
storage of information.
biological catalysis.
energy storage.
cell-to-cell communication.

Transmission and Storage

Is the following statement about DNA and RNA true or false?
A hydrogen atom is present on the 3′ carbon of the ribose of DNA nucleotides, whereas a hydroxyl group is present at the same position on RNA nucleotides.

False

Is the following statement about DNA and RNA true or false?
DNA is a double-stranded molecule, and RNA is single-stranded.

True

When a mixture of debris from killed virulent bacteria and living non-virulent bacteria are injected into mice:

1. the mice are killed because the virulent bacteria are revived.
2. the mice survive because none of the living bacteria are virulent.
3. the mice survive for a period of a few weeks and then die from an unrelated illness.
4. half the mice are killed and the other half survive.
5. the mice are killed because the non-virulent bacteria are transformed into virulent bacteria.

5

In the DNA sequence 5′-TGAC-3′, the phosphodiester linkage between the guanine and the adenine connects:
1. the 3′ end of the guanine to the 5′ end of the adenine.
2. the 2′ end of the adenine to the 3′ end of the guanine.
3. the 5′ end of the guanine to the 1′ end of the adenine.
4. the 3′ end of the adenine to the 5′ end of the guanine.
5. the 5′ end of the guanine to the 2′ end of the adenine.

1

he central dogma of molecular biology states that information flows from:

DNA directly to proteins.
protein to RNA to DNA.
DNA to RNA to protein.
RNA to protein to DNA.
RNA to DNA to protein.

DNA to RNA to Protein

Translation is the process by which:
1. the information in DNA is used to synthesize an exact copy of that DNA.
2. ribosomes synthesize protein from information in an RNA molecule.
3. a section of DNA is used as information to generate an RNA molecule.
4. an RNA molecule is used to repair damage to a related DNA molecule.
5. ribosomes read the information in a DNA molecule and use it to synthesize protein.

2

A template strand of DNA is read in the ____________ direction in order to direct synthesis of RNA in the ____________ direction.

3′-5′; 3′-5′
5′-3′; 3′-5′
3′-5′; 5′-3′
5′-3′; 5′-3′

3′-5′;5′-3′

Transcription continues until:

all bases in the DNA are copied.
a stop codon is encountered.
a terminator sequence is encountered.
a ribosome pulls RNA polymerase off the DNA.
a transcription factor signals the end of the gene.

Terminator

True or False: during transcription of a given protein-coding gene, both strands are used as template.

False

The strands in a DNA molecule are: (choose all that apply)

antiparallel.
complementary.
identical.
perpendicular.
covalently bonded to each other.

Antiparallel and Complementary

Where does the energy come from to add a uracil to the 3′ end of a transcript?
1. The energy released by allowing the uracil to complementary base pair with an adjacent thymine
2. The hydrolysis of a single phosphate from the incoming UTP molecule
3. The cell’s supply of ATP
4. The hydrolysis of pyrophosphate from the incoming UTP molecule
5. The hydrolysis of all three phosphate groups from the incoming UTP molecule

4

Is the following statement about DNA and RNA true or false?

RNA is the primary long-term storage molecule for genetic information in eukaryotic cells.

False

Which of the following correctly indicates the complementary base pairing of adenine in DNA and RNA?
1. adenine with thymine in both DNA and RNA
2. adenine with uracil in DNA and with thymine in RNA
3. adenine with thymine in DNA and with uracil in RNA
4. adenine with cytosine in DNA and with guanine in RNA
5. adenine with guanine in DNA and with cytosine in RNA

3

The type of RNA that physically interacts with a ribosome, providing the sequence information for a specific protein, is abbreviated:

rRNA.
siRNA.
mRNA.
snRNA.
tRNA.

mRNA

In the spiral staircase analogy of DNA structure, each railing represents a ____________.

1. sugar-phosphate backbone, and each step represents a pair of nitrogenous bases
2. sugar-phosphate backbone, and each step represents a nitrogenous base
3. nitrogenous base, and the steps represent the sugar-phosphate backbone of the DNA molecule

1

Imagine you have discovered a new species of bacteria. To begin your investigation of this organism, you run an assay on the total nucleotide content of the bacterial cells. If the cytosine content of DNA from the bacterial cells is 17%, what is the adenine content?

17%
34%
66%
33%
It is impossible to calculate this number for eukaryotes.

33%

Is the following statement about DNA and RNA true or false?

The nitrogenous base thymine is present in DNA and RNA, while uracil is present only in RNA.

False

Is the following statement about DNA and RNA true or false?

DNA is a double-stranded molecule, and RNA is single-stranded.

True

RNA polymerase can do which one of the following?

Allow RNA-DNA hybrids to form
Release a finished RNA transcript from a DNA template
Separate DNA strands
Restore the original DNA strands
RNA polymerase is capable of all of these activities.

All

Which one of the following is a critical region of a tRNA molecule?

Amino acid attachment site
Anticodon loop
Stop codon
Amino acid attachment site and anticodon loop
All of these choices are correct.

Amino Acid Attachment Site and Anticodon Loop

A polycistronic mRNA with six protein coding genes would have:

1 start codon and 1 stop codon.
1 start codon and 6 stop codons.
6 start codons and 1 stop codon.
6 start codons and 6 stop codons.
3 start codons and 3 stop codons.

6 Start, 6 Stop

Which one of the following mRNA processing events does not occur in the nucleus of human cells?

5′ cap addition
excision of introns
poly-A tail addition
splicing of exons
None of the above are correct. All of the processing events described above occur in the nucleus of human cells.

None

Non-protein coding genes are typically found in:

the nucleolus.
areas of the nucleus other than the nucleolus.
the cytoplasm.
mitochondria.
the endoplasmic reticulum.

Nucleolus

How many water molecules would be produced in making a polypeptide that is 14 amino acids long?

0
13
14
28

13

The three-dimensional shape of a protein is determined by the primary, secondary, tertiary, and in many cases, the quaternary structure of the protein. The following sentence is taken from scientific articles on protein structure. Choose the level of protein structure that applies best to the sentence.

"Peptide bonds form between the monomers."

Primary
Secondary
Tertiary
Quaternary

Primary

How many different types of aminoacyl tRNA synthetases are there?

2
4
20
61
64

20

The three-dimensional shape of a protein is determined by the primary, secondary, tertiary, and in many cases, the quaternary structure of the protein. The following sentence is taken from scientific articles on protein structure. Choose the level of protein structure that applies best to the sentence.

"There are extensive ionic interactions between positively charged R-groups and negatively charged R-groups on the polypeptide."

Primary
Secondary
Tertiary
Quaternary

Tertiary

When the peptide bond is created between amino acid 1 and amino acid 2:

1. the amino group of amino acid 1 is joined to the carboxyl group of amino acid 2.
2. the carboxyl group of amino acid 1 is joined to the amino group of amino acid 2.
3. the carboxyl group of amino acid 1 is joined to the carboxyl group of amino acid 2.
4. the amino group of amino acid 1 is joined to the amino group of amino acid 2.

2

The unfolding of a protein by heat or chemical treatment is referred to as:

Denaturation

True or False: amino acids with hydrophobic side chains are most often found buried in the interior of folded proteins.

True

Long, saturated fatty acid tails ____________ lipid mobility and ____________ membrane fluidity.

enhance; increase
reduce; increase
maintain; decrease
enhance; maintain
reduce; decrease

reduce; decrease

Which of the following best describes the hydrophilic component of cholesterol?

a hydroxyl group only
a phosphate group only
a phosphate group and a chemical group called choline
a group of four planar rings and a hydroxyl group
a single hydrocarbon tail

Hydroxyl Group

The lipid components of cellular membranes include ____________.

phospholipids
phospholipids and fatty acids
fatty acids and cholesterol
phospholipids and cholesterol

Phospholipids and Cholesterol

Which of the choices below can be used to correctly begin the following sentence?

"____________ have a plasma membrane."

All cells
All animal and plant cells, but not bacterial cells,
All bacterial cells, but not animal and plant cells,
All plant and bacterial cells, but not animal cells,

All cells

Specific types of lipids assemble into defined areas of a biological membrane referred to as:

sphingopatches.
lipid rafts.
biomembrane aggregation regions (BARs).
plaques.
cholesterol plugs.

Lipid Rafts

Which property of phospholipids allows membrane proteins involved in the same biochemical pathway to associate with each other?

formation of lipid rafts
flip-flop of individual phospholipids
amphipathic nature of the phospholipids
decreased fluidity of the membrane due to carbon-carbon double bonds

Formation of Lipid Rafts

Phospholipase is an enzyme that cleaves the phosphate head group off a phospholipid molecule. The plasma membrane is not, however, permeable to the enzyme. Imagine a cell where phospholipid A is present in the monolayer facing the exterior of the cell, and phospholipid B is present in the monolayer facing the interior of the cell. After adding phospholipase to the medium in which the cell is growing, what would you expect to find in the fluid surrounding the cell?
1. the phosphate head group from phospholipid A only
2. the phosphate head group from phospholipid B only
3. phosphate head groups from both phospholipids A and B
4. phosphate head groups from neither phospholipids A nor B

1

Which of the following is a common function of membrane proteins? Select all correct choices.

catalysis
attachment
transport
signal reception

All of them

Which of the following would be considered an integral membrane protein?
1. a protein with its N-terminus in the cytoplasm and its C-terminus in the extracellular space
2. a protein attached to a transmembrane protein via hydrogen bonding
3. a protein attached to a phospholipid via ionic bonding with the head group of the lipid molecule
4. a protein capable of diffusing throughout the cytoplasm of a cell

1

If FRAP is performed on two membranes, one at 25ºC and the other at 40ºC, which one of the following results would most likely be observed?
1. Only the membrane at the higher temperature would be capable of recovering fluorescence in the bleached area.
2. Only the membrane at the lower temperature would be capable of recovering fluorescence in the bleached area.
3. Both membranes would recover fluorescence in the bleached area, but the membrane at the colder temperature would recover more rapidly.
4. Both membranes would recover fluorescence in the bleached area, but the membrane at the warmer temperature would recover more rapidly.
5. Both membranes would recover fluorescence in the bleached area, and at the same rate.

4

Which one of the following would be least likely to cross a lipid bilayer?

O2
CO2
ATP
H2O
N2

ATP

The process of a vesicle fusing with the plasma membrane and depositing its contents into the extracellular space is most specifically referred to as:

active transport.
endocytosis.
budding.
exocytosis.
bridging.

Exocytosis

A transmembrane protein in the outer membrane of the nuclear envelope would least likely be found later in which one of the following cellular locations?

the plasma membrane
a lysosomal membrane
a mitochondrial membrane
the Golgi apparatus membrane
the rough endoplasmic reticulum membrane

Mitochondrial Membrane

RNA molecules are transported from the nucleus to the cytoplasm in eukaryotes through:

sodium/potassium channels.
aquaporins.
passive diffusion.
budding off of the nuclear envelope.
nuclear pore complexes.

Nuclear Pore Complexes

In which of the following can protein synthesis occur in eukaryotes? Select all correct choices.

the cytoplasm
the rough endoplasmic reticulum
the nucleus

Cytoplasm and Rough ER

The Golgi apparatus is responsible for at least a portion of a eukaryote’s: (select all correct choices)

carbohydrate synthesis.
modification of lipids synthesized in the ER.
targeting of proteins to their final destinations.
modification of proteins synthesized in the ER.

All

A protein with an internal signal sequence is most likely to be located in:

the nucleus.
a mitochondrion.
the cytoplasm.
a chloroplast.
the extracellular space.

Nucleus

With which of the following is a signal-recognition particle (SRP) capable of interacting? Select all correct choices.

an SRP receptor
a ribosome
a signal sequence in a protein destined for the ER

All

Which of the following accurately describes the path travelled by a new protein as it is
synthesized and released from the cell?
1. plasma membrane → ER → transport vesicle → Golgi → cytosol → external environment
2. cytosol → ER → Golgi → transport vesicle → plasma membrane → external environment
3. nuclear envelope → ER → transport vesicle → Golgi → plasma membrane → external environment

2

Imagine that you are investigating the production of insulin in normal cells. You are using these cells to help determine the cause of faulty insulin production in other cells where insulin appears to be synthesized but fails to be secreted from the cell. You design experiments using three different pharmaceutical compounds to help pinpoint the trouble spot in the protein synthetic pathway. The first compound blocks transport vesicle movement in the cytoplasm. The second blocks the SRP release from the ribosome and mRNA. The third compound binds to and blocks the signal sequence so the SRP cannot recognize it.

Which of the following describes what you would expect to observe in cells treated with the inhibitor of transport vesicle movement?

an accumulation of insulin in the cytosol
an accumulation of insulin in the Golgi
an accumulation of insulin at the plasma membrane
a lack of insulin in the cell

Accumulation of Insulin in the Golgi

Imagine that you are investigating the production of insulin in normal cells. You are using these cells to help determine the cause of faulty insulin production in other cells where insulin appears to be synthesized but fails to be secreted from the cell. You design experiments using three different pharmaceutical compounds to help pinpoint the trouble spot in the protein synthetic pathway. The first compound blocks transport vesicle movement in the cytoplasm. The second blocks the SRP release from the ribosome and mRNA. The third compound binds to and blocks the signal sequence so the SRP cannot recognize it.

Which of the following describes what you would expect to observe in cells treated with the inhibitor of SRP release from the ribosome and mRNA?

an accumulation of insulin in the cytosol
an accumulation of insulin in the Golgi
an accumulation of insulin at the plasma membrane
a lack of insulin in the cell

Lack of Insulin in Cell

Imagine that you are investigating the production of insulin in normal cells. You are using these cells to help determine the cause of faulty insulin production in other cells where insulin appears to be synthesized but fails to be secreted from the cell. You design experiments using three different pharmaceutical compounds to help pinpoint the trouble spot in the protein synthetic pathway. The first compound blocks transport vesicle movement in the cytoplasm. The second blocks the SRP release from the ribosome and mRNA. The third compound binds to and blocks the signal sequence so the SRP cannot recognize it.

Which of the following describes what you would expect to observe in cells treated with the compound that prevents the recognition of the signal sequence by the SRP?

an accumulation of insulin in the cytosol
an accumulation of insulin in the Golgi
an accumulation of insulin at the plasma membrane
a lack of insulin in the cell

Accumulation of Insulin in Cytosol

Some diseases, such as Tay-Sachs, are caused by the defective breakdown of cellular components. Which of the following organelles is defective?

plasma membrane
ribosome
endoplasmic reticulum
Golgi apparatus
lysosome

Lysosome

You are investigating a particular cell type, and you notice that a protein normally found in the lysosome ends up being secreted from the cell. This appears to be the only thing wrong with these cells. Of the following conditions, which is the most likely cause of this defect in these cells?

The lysosome leaks the protein out of the cell.
The signal sequence on the lysosomal protein is defective.
Transport vesicles responsible for sorting in the cell are defective.
The pH of the lysosome is not low enough for the protein to remain in it.

Signal sequence is Defective

Anabolic pathways of metabolism are pathways that:

build complex molecules from simple ones.
release stored chemical energy.
take place primarily in skeletal muscle.
make large quantities of ATP.

Build

The assembly of glucose into polysaccharides: (select all that apply)

is an anabolic process
is a catabolic process
takes place in some plant cells but not in animal cells
takes place in some animal cells but not in plant cells
takes place in some plant cells and in some animal cells

Anabolic process takes place in some plant cells and in some animal cells

Which one of the following is the most common energy "currency" for a cell?

ATP
DNA
glucose
protein
NADH

ATP

Which of the following is a component of a molecule of ATP? Select all correct choices.

three phosphate groups
ribose
adenine
three phosphate groups and ribose

All

The potential energy in a molecule of ATP is held in the:

carbon-carbon bonds of the sugar.
repulsion of the phosphate groups from each other.
the carbon-nitrogen bonds of the base.
the carbon-oxygen bonds of the sugar.
repulsion of the sugar and the base.

Repulsion of Phosphate Groups

ATP is chemically related most closely to which of the following?

glucose
testosterone
phospholipid
thymine nucleotide
tryptophan amino acid

Thymine Nucleotide

Which of the following statements is NOT one of the laws of thermodynamics?

All cells arise from pre-existing cells.
The amount of energy in the universe is constant.
The energy available to do work decreases as energy is transferred from one form to another.
None of the statements in these choices is a law of thermodynamic

All cells arise from pre-existing cells

Complete the following with regard to entropy as a measure of disorder. Predict which of the following transformations of related molecules would include a change from more entropy to less entropy?

the conversion of monosaccharides to starch
the conversion of a polypeptide to amino acids
the conversion of RNA to nucleotides
salt crystals dissolving in an aqueous solution

Conversion of monosaccharides to starch

Suppose you use a match to ignite a sheet of paper from your notebook, and allow the fire to continue until the burning stops. If you could measure all the energy in the resulting combustion products, and all the energy in the heat released (including whatever increase in disorder has occurred), would you predict this amount to be more than, less than, or the same amount as the amount of potential energy in the starting sheet of paper? (You should ignore the activation energy provided by the match to light the paper.)

more energy than the paper
less energy than the paper
the same energy as the paper

Same

ATP is a good energy currency for cells because it has a(n) ____________ amount of Gibbs free energy.

very low
intermediate
very high

Intermediate

It is often stated that the phosphate bonds in ATP are "high energy," but in fact, they are not notably high in energy. Rather, they are easy to break, and the ∆G of hydrolysis is a "useful" quantity of energy. What makes the phosphate bonds easy to break?

They are close to the destabilizing nitrogenous base adenosine.
The positive charges on amino groups repel each other.
The negative charges on the phosphate groups repel each other.
The high alkalinity attacks bonds between the phosphate groups.

Negative charges on phosphate groups repel

What is the purpose of an enzyme?

to increase the rate of a specific reaction
to decrease the transition state
to alter the equilibrium of a specific reaction
to both increase the rate of a specific reaction and decrease the transition state

Both increase rate and decrease transition state

True or False: the amino acids that actively contribute to catalysis in an enzyme do not have to be located adjacent to each other in the primary sequence (the linear sequence of amino acids) of the protein.

True

Three critical amino acids in the active site of an enzyme are leucine, tryptophan, and alanine. Which of the following characteristics would you predict the substrate to possess in order to bind the active site of this enzyme?

relatively hydrophobic
hydrophilic, with a negative charge
hydrophilic, with a positive charge
hydrophilic, but without a charge

Relatively Hydrophobic

Three critical amino acids in the active site of an enzyme are threonine, serine, and glutamic acid. Which of the following characteristics would you predict the substrate to possess in order to bind the active site of this enzyme?

relatively hydrophobic
hydrophilic, with a negative charge
hydrophilic, with a positive charge

Hydrophilic, + charge

True or False: a cellular reaction with a ΔG of 8.5 kcal/mol could be effectively coupled to the hydrolysis of a single molecule of ATP.

False

In most living cells, which one of the following is not a product of cellular respiration?

carbon dioxide
water
oxygen
ATP
All of these choices are products of cellular respiration in most living cells.

Oxygen

During which stage(s) of cellular respiration is(are) carbon dioxide released?

stage 1 only
stages 1 and 2
stages 2 and 3
stage 3 only
stages 3 and 4

Stages 2 & 3

In which form are electrons transferred during typical redox reactions such as the oxidation of glucose?

as free electrons
as hydrogen atoms
as oxygen atoms
as carbon atoms
as phosphate groups

As Hydrogen Atoms

The energy in organic molecules is released in a series of steps because:

it is not possible to release it in a single step.
more total energy is released in multiple steps than would be released in a single step.
less total energy is released in multiple steps than would be released in a single step.
more energy can be harvested for cellular use in multiple steps than from a single step.
only a single electron can be moved at a time in a cellular reaction

More energy can be harvested in multiple steps

Which one of the following represents the reduced forms of the two major biological cofactors?

NAD+ and FAD
NAD+ and FADH2
NADH and FAD
NADH and FADH2

NADH and FADH2

Which of these summarizes the overall reactions of cellular respiration?

C6H12O6 + 6 O2 → 6 CO2 + 6 H2O + energy

6 CO2 + 6 H2O + energy → C6H12O6 + 6 O2

C6H12O6 + 6 O2 + energy → 6 CO2 + 12 H2O

6 CO2 + 6 O2 → C6H12O6 + 6 H2O

H2O → 2 H+ + 1/2 O2 + 2e-

C6H12O6 + 6 O2 → 6 CO2 + 6 H2O + energy

Cellular respiration releases energy. In cellular respiration:

organic molecules such as carbohydrates are converted to chemical energy that can be used to do the work of the cell.
the chemical potential energy stored in organic molecules is converted to chemical energy that can be used to do the work of the cell.
chemical potential energy in the bonds of ADP is transferred to the chemical potential energy in the bonds of ATP.

Chemical PE stored in organic molecules is converted to Chemical E that can be used to do work of cell

An organism that carries out cellular respiration in its mitochondria:

may be a cell from a terrestrial plant.
may be a prokaryotic cell from the domain Archaea.
is a bacterium.
may be any kind of cell.

May be a cell from terrestrial plant

In eukaryotic cells, glycolysis occurs in:

the cytoplasm.
the nucleus.
the matrix of the mitochondria.
the endoplasmic reticulum.

Cytoplasm

The phosphorylation of glucose during glycolysis serves to: (select all that apply)

destabilize the molecule, making it easier to cleave.
trap imported glucose inside the cell.
reduce a biological cofactor, storing energy for late

Destabilize and Trap

Which of the following is a net product of glycolysis? Select all correct choices.

2 pyruvate
2 ATP
2 NADH

All

An individual’s ability to excel in certain types of sports may be due to different muscle fiber types. Certain muscle types allow some people, like marathoners, to have the ability to be involved in sports which require sustained activity of their muscles, while other muscle types, like in sprinters, allow people to excel in sports which require a rapid burst of muscle activity but fatigue quickly. The sustained activity of muscles in marathon runners is due to the higher yield of ATP per glucose. What differences would you predict for marathoners’ muscles compared to sprinters’? Select all correct answers.

1. Marathoners’ muscles use a different set of enzymes for cellular respiration.
2. Marathoners’ muscles rely more on oxidative phosphorylation.
3. Marathoners’ muscles require greater oxygen delivery to the muscle cells.
4. Marathoners’ muscles have a greater number of mitochondria.

2,3,4

You are trying to find the best maximum source of energy for an organism. Which of the following compounds would you choose?

glucose
oxygen
ATP
pyruvate
NADH

Glucose

In eukaryotic cells, the oxidation of pyruvate occurs in:

the cytoplasm.
the nucleus.
the matrix of the mitochondria.
the endoplasmic reticulum.
vacuoles.

Mitochondrial Matrix

When fats are used as an energy source, the fatty acids are broken down to acetyl-CoA. That means that fats bypass the reactions of ____________ and enter the respiratory pathway at ____________.

glycolysis; the citric acid cycle
fermentation; glycolysis
the citric acid cycle; oxidative phosphorylation
the citric acid cycle; glycolysis
oxidative phosphorylation; fermentation

Glycolysis; Citric Acid Cycle

Which of the following is a net product of the citric acid cycle for each molecule of pyruvate generated in glycolysis? Select all correct choices.

1 ATP
3 NADH
1 FADH2

All

Following the citric acid cycle but before the electron transport chain and oxidative phosphorylation, most of the energy from the original glucose molecule is found in ____________.

acetyl-CoA
CO2
pyruvate
NADH
ATP

NADH

Which of the following molecules has the greatest potential energy?

ATP
NADH
NAD+
FAD
FADH2

NADH

If oxygen is unavailable, predict what happens to the citric acid cycle.

It stops because the supplies of NAD+ and FAD become depleted.
It stops because ADP levels increase in the absence of oxygen.
It continues because none of the reactions in the citric acid cycle require oxygen.
It continues because ATP levels are low, and low ATP activates enzymes of the cycle.

Stops because supplies of NAD+ and FAD become depleted

When oxygen is depleted, the citric acid cycle stops. Which of the following would you need to add to the system to restore activity? Indicate all that apply.

glucose
NAD+
NADH
FAD
acetyl-CoA

NAD+ & FAD

Each round of the citric acid cycle begins when the 4-carbon molecule oxaloacetate is converted to the 6-carbon molecule citrate. As the cycle progresses, two carbons are eliminated to regenerate the oxaloacetate. The added carbon is supplied by ____________ and the two eliminated carbons are released as ____________.

ATP; acetyl-CoA

CO2; pyruvate

acetyl-CoA; CO2

CO2; NADH

CO2; acetyl-CoA

Acetyl-CoA; CO2

Complete oxidation of glucose to CO2 involves two different mechanisms for synthesizing ATP, oxidative phosphorylation, and substrate-level phosphorylation. Substrate-level phosphorylation: (select all that apply)

requires activity of the enzyme ATP synthase.
occurs in the mitochondria.
occurs across the inner mitochondrial membrane.
requires an electron transport chain.
occurs in the cytosol.

Occurs in Mitochondria, Occurs in Cytosol

True or False: the energy from the movement of electrons through the electron-transport chain is directly used to synthesize ATP.

False

Animals breathe in air containing oxygen and breathe out air with less oxygen. The consumed oxygen is used:

in the Krebs cycle.
in the glycolysis pathway.
in the conversion of pyruvate to acetyl Co-A.
in photosynthesis.
as an electron acceptor in the respiratory electron transport chain.

As electron acceptor in respiratory electron transport chain

Certain complexes of the mitochondrial electron transport chain pump protons. Which of the following best describes the movement of protons in this situation?

across the outer mitochondrial membrane, from the cytoplasm to the intermembrane space
across the outer mitochondrial membrane, from the intermembrane space to the cytoplasm
across the inner mitochondrial membrane, from the intermembrane space to the matrix
across the inner mitochondrial membrane, from the matrix to the intermembrane space

Across inner mitochondrial membrane, from matrix to intermembrane space

DNP (2,4-dinitrophenol) is an effective weight-loss agent that was used in diet pills in the 1930s. It has since been removed from the market (though it is available online) because of serious side effects such as fever, cataracts, rashes, and sometimes death. DNP inserts into the inner mitochondrial membrane and shuttles protons between the intermembrane space and the matrix. Based on this information, which of the following might you predict?

increased hydrolysis of ATP
reduced ATP production
dissipation of the proton gradient
increased ATP production
decreased difference in pH between matrix and intermembrane space

Reduced ATP production, dissipation of proton gradient, decreased difference in pH between matrix and intermembrane space

Atractyloside is a poison that inhibits the transport of ADP from the cytosol across the mitochondrial membranes and into the mitochondrial matrix. The direct effect of this drug is to stop ATP synthesis because:

ADP is a necessary substrate for the reaction catalyzed by ATP synthase.
it prevents proton pumping across the inner mitochondrial membrane.
it prevents electron transfer to O2.
it prevents electron transfer from NADH to complex I.

ADP necessary substrate

Very low concentrations of detergent make membranes leaky to small molecules and ions without damaging proteins. In isolated mitochondria exposed to detergent, the molecules of the electron transport chain and of ATP synthase remain intact. Do you expect ATP synthesis to continue in the presence of low concentrations of detergent?

Yes, because all enzymes and electron carriers are functional.
No, because with a leaky membrane, H+ gradient cannot be maintained.
No, because leaky membranes do not allow NADH and FADH2 to donate their electrons to the electron transport chain.
No, because leaky membranes inhibit glycolysis.

No, H+ gradient cannot be maintained

The pH in the intermembrane space of the mitochondria should be ____________ compared to the matrix due to the ____________.

lower; higher concentration of H+ in the intermembrane space

higher; higher concentration of H+ in the intermembrane space

higher; lower concentration of H+ in the intermembrane space

lower; lower concentration of H+ in the intermembrane space

lower, higher H+ in intermembrane

Bread making requires yeast, flour and water. Why is yeast used?

It makes the bread healthier as yeast is a source of vitamins.
It makes the bread rise due to the carbon dioxide released during ethanol fermentation.
It makes the bread rise due to the carbon dioxide released during cellular respiration.
It makes the bread sour due to lactic acid fermentation.
It makes the bread crunchy.

Make bread rise due to CO2 released during ethanol fermentation

Energy from glucose can be extracted and converted to ATP only if: (select all correct answers)

oxygen is the electron acceptor.
the cells have mitochondria.
the cells have membrane proteins that can pump hydrogen ions.
the cells have enzymes that can carry out oxidation-reduction reactions.
the cells have enzymes that can carry out glycolysis.

Cells have enzymes that carry out Redox, cells have enzymes that carry out glycolysis