A localized group of organisms that belong to the same species is called a
A) biosystem
B) community
C) population
D) ecosystem
E) family

C. population

Knowing just the atomic mass of an element allows inferences about which of the following?
A) the chemical properties of the element
B) the number of protons in the element
C) the number of neutrons in the element
D) the number of protons plus neutrons in the element

D. the number of protons plus neutrons in the element

Which of the following would be regarded as compounds?
A) H₂O, O₂, and CH₄
B) H₂O and O₂
C) O₂ and CH₄
D) CH₄ and O₂, but not H₂O
E) H₂O and CH₄, but not O₂

E. H₂O and CH₄, but not O₂

Which of the following correctly describes any reaction that has reached chemical equilibrium?
A) The concentration of the reactants equals the concentration of the products.
B) The rate of the forward reaction is equal to the rate of the reverse reaction.
C) All of the reactants have been converted to the products of the reaction.
D) All of the products have been converted to the reactants of the reaction.
E) Both the forward and the reverse reactions have stopped with no net effect on the concentration of the reactants and the products.

B) The rate of the forward reaction is equal to the rate of the reverse reaction.

Water molecules are attracted to one another by _______.

1. hydrophobic interactions
2. hydrogen bonds
3. ionic bonds
4. nonpolar covalent bonds

B. hydrogen bonds

In a single molecule of water, two hydrogen atoms are bonded to a single oxygen atom by_____.

1. nonpolar covalent bonds
2. polar covalent bonds
3. ionic bonds
4. hydrogen bonds

B. polar covalent bonds

Which of the following is a property of liquid water? Liquid water_____.

1. is nonpolar
2. has a heat of vaporization that is higher than that of most other substances
3. is less dense than ice
4. has a specific heat that is lower than that for most other substances

B. has a heat of vaporization that is higher than that of most other substances

Which of the following can be attributed to water's high specific heat?

1. Oil and water do not mix well
2. Ice floats on water
3. Sugar dissolves in hot tea faster than in iced tea
4. A lake heats up more slowly than the air around it

D. A lake heats up more slowly than the air around it

Water has many exceptional an useful properties. Which is the rarest property among compounds?

1. Water has a high heat capacity
2. Water has surface tension
3. Water is a solvent
4. Solid water is less dense than liquid water

D. Solid water is less dense than liquid water

The partial negative charge at one end of the water molecule....

Answer: a hydrogen bond

Answer: a hydrogen bond

Which type of bond must be broken for water to vaporize?

A) ionic bonds

B) both hydrogen bonds and ionic bonds
C) polar covalent bonds
D) hydrogen bonds

D. hydrogen bonds

The element present in all organic molecules is
A) hydrogen.
B) oxygen.
C) carbon.
D) nitrogen.

C) carbon.

Stanley Miller's 1953 experiments supported the hypothesis that_____.
A) life arose on Earth from simple inorganic molecules.
B) organic molecules can be synthesized abiotically under conditions that may have existed on early Earth.
C) life arose on Earth from simple organic molecules, with energy from lightning and volcanoes.
D) the conditions on early Earth were conducive to the origin of life.

B) organic molecules can be synthesized abiotically under conditions that may have existed on early Earth.

Why is carbon so important in biology?

1. It is a common element on Earth
2. It can form a variety of carbon skeletons and host functional groups
3. It bonds to only a few other elements
4. It has very little electronegativity, making it a good electron donor

B. It can form a variety of carbon skeletons and host functional groups

What determines whether a carbon atom's covalent bonds to other atoms are in a tetrahedral configuration or a planar configuration?
A) the presence or absence of bonds with oxygen atoms
B) the presence or absence of double bonds between the carbon atom and other atoms
C) the polarity of the covalent bonds between carbon and other atoms
D) the presence or absence of bonds with nitrogen atoms

B) the presence or absence of double bonds between the carbon atom and other atoms

Which of these classes of biological molecules does NOT include polymers?

1. nucleic acids
2. proteins
3. carbohydrates
4. lipids

D. lipids

How many molecules of water are used to completely hydrolyze a polymer that is 11 monomers long?

1. 9
2. 10
3. 12
4. 11

B. 10

Nucleic acids are polymers made up of which of the following monomers?

1. sugars
2. amino acids
3. nucleotides
4. nitrogenous bases

C. nucleotides

Which of the following best summarizes the relationship between dehydration reactions and hydrolysis?

1. Dehydration reactions eliminate water from membranes; hydrolysis reactions add water to membranes.
2. Dehydration reactions and hydrolysis reactions assemble polymers form monomers
3. Hydrolysis reactions create polymers and dehydration reactions create monomers
4. Dehydration reactions assemble polymers; hydrolysis reactions break polymers apart

D. Dehydration reactions assemble polymers; hydrolysis reactions break polymers apart

How do phospholipids interact with water molecules?

1. The polar heads interact with water; the nonpolar tails do not
2. Phospholipids dissolve in water.
3. Phospholipids do not interact with water because water is polar and lipids are nonpolar.
4. The polar heads avoid water; the nonpolar tails attract water (because water is polar and opposites attract.

A. The polar heads interact with water; the nonpolar tails do not

Which of the following is NOT a component of each monomer used to make proteins?

1. an amino functional group, NH2
2. a side chain, R
3. a carboxyl group, COOH
4. a phosphorus atom, P

D. a phosphorus atom, P

Which of the following is the strongest evidence that protein structure and function are correlated?

1. Proteins have four distinct levels of structure and many functions
2. Enzymes tend to be globular in shape
3. Proteins function best at certain temperatures
4. Denatured proteins (unfolded) proteins do not function normally

D. Denatured proteins (unfolded) proteins do not function normally

The advantage of light microscopy over electron microscopy is that

A) light microscopy allows one to view dynamic processes in living cells.

B) light microscopy provides for higher resolving power than electron microscopy.

C) specimen preparation for light microcopy does not produce artifacts.

D) light microscopy provides higher contrast than electron microscopy.

A) light microscopy allows one to view dynamic processes in living cells.

The evolution of eukaryotic cells most likely involved

1. acquisition of an endomembrane system, and subsequent evolution of mitochondria from a portion of the Golgi.
2. anaerobic archaea taking up residence inside a larger bacterial host cell to escape toxic oxygen-the anaerobic bacterium evolved into chloroplasts.
3. endosymbiosis of an aerobic bacterium in a larger host cell-the endosymbiont evolved into mitochondria.
4. an endosymbiotic fungal cell evolved into the nucleus.

C. endosymbiosis of an aerobic bacterium in a larger host cell-the endosymbiont evolved into mitochondria.

Motor proteins provide for molecular motion in cells by interacting with what types of cellular structures?

1. membrane proteins
2. cellulose fibers in the cell wall
3. cytoskeletal structures
4. sites of energy production in cellular respiration

C. cytoskeletal structures

Which of the following is a characteristic feature of a carrier protein in a plasma membrane?

1. It requires the expenditure of cellular energy to function
2. It has no hydrophobic regions
3. It exhibits a specificity for a particular type of molecule
4. It works against diffusion

C. It exhibits a specificity for a particular type of molecule

What kinds of molecules pass through a cell membrane most easily?

1. ionic
2. large polar
3. small and hydrophobic
4. large and hydrophobic

C. small and hydrophobic

Why are lipids and proteins free to move laterally in membranes?

A) The interior of the membrane is filled with liquid water.

B) Lipids and proteins repulse each other in the membrane.

C) Hydrophilic portions of the lipids are in the interior of the membrane.

D) There are only weak hydrophobic interactions in the interior of the membrane

D) There are only weak hydrophobic interactions in the interior of the membrane

According to the fluid mosaic model of cell membranes, phospholipids _____.

1. A) can move laterally along the plane of the membrane
2. B) frequently flip-flop from one side of the membrane to the other
3. C) occur in an uninterrupted bilayer, with membrane proteins restricted to the surface of the membrane
4. D) have hydrophilic tails in the interior of the membrane

A) can move laterally along the plane of the membrane

Which of the following allows water to move much faster across cell membranes?

1. A) the sodium-potassium pump
2. B) ATP
3. C) peripheral proteins
4. D) aquaporins

D. aquaporins

The solutions in the arms of a U-tube are separated at the bottom of the tube by a selectively permeable membrane. The membrane is permeable to sodium chloride but not to glucose. Side A is filled with a solution of 0.4 M glucose and 0.5 M sodium chloride (NaCl), and side B is filled with a solution containing 0.8 M glucose and 0.4 M sodium chloride. Initially, the volume in both arms is the same.

At the beginning of the experiment,
A) side A is hypertonic to side B.
B) side A is hypotonic to side B.
C) side A is isotonic to side B.
D) side A is hypertonic to side B with respect to glucose.

B) side A is hypotonic to side B

Which of the following is true of metabolism in its entirety in all organisms?
A) Metabolism depends on a constant supply of energy from food.
B) Metabolism depends on an organism's adequate hydration.
C) Metabolism uses all of an organism's resources.
D) Metabolism consists of all the energy transformation reactions in an organism.
E) Metabolism manages the increase of entropy in an organism.

D) Metabolism consists of all the energy transformation reactions in an organism.

Which of the following is a statement of the first law of thermodynamics?
A) Energy cannot be created or destroyed.
B) The entropy of the universe is decreasing.
C) The entropy of the universe is constant.
D) Kinetic energy is stored energy that results from the specific arrangement of matter.

A) Energy cannot be created or destroyed.

The active site of an enzyme is the region that
A) binds allosteric regulators of the enzyme.
B) is involved in the catalytic reaction of the enzyme.
C) binds noncompetitive inhibitors of the enzyme.
D) is inhibited by the presence of a coenzyme or a cofactor.

B) is involved in the catalytic reaction of the enzyme.

Which of the following statements is representative of the second law of thermodynamics?

1. A) Conversion of energy from one form to another is always accompanied by some gain of free energy.
2. B) Without an input of energy, organisms would tend toward decreasing entropy.
3. C) Cells require a constant input of energy to maintain their high level of organization.
4. D) Every energy transformation by a cell decreases the entropy of the universe.

C) Cells require a constant input of energy to maintain their high level of organization

Which of the following statements is a logical consequence of the second law of thermodynamics?

1. A) If the entropy of a system increases, there must be a corresponding decrease in the entropy of the universe.
2. B) If there is an increase in the energy of a system, there must be a corresponding decrease in the energy of the rest of the universe.
3. C) Every chemical reaction must increase the total entropy of the universe.
4. D) Energy can be transferred or transformed, but it cannot be created or destroyed.

C) Every chemical reaction must increase the total entropy of the universe.

Which of the following involves a decrease in entropy?

1. A) condensation reactions
2. B) reactions that separate monomers
3. C) depolymerization reactions
4. D) hydrolysis reactions

A) condensation reactions

Which term most precisely describes the cellular process of breaking down large molecules into smaller ones?

1. A) catabolism (catabolic pathways)
2. B) metabolism
3. C) anabolism (anabolic pathways)
4. D) dehydration

A) catabolism (catabolic pathways)

The mathematical expression for the change in free energy of a system is ΔG =ΔH - TΔS. Which of the following is (are) correct?

1. A) ΔS is the change in enthalpy, a measure of randomness.
2. B) ΔH is the change in entropy, the energy available to do work.
3. C) ΔG is the change in free energy.
4. D) T is the temperature in degrees Celsius.

C) ΔG is the change in free energy.

In solution, why do hydrolysis reactions occur more readily than condensation reactions?

1. A) Hydrolysis increases entropy and is exergonic.
2. B) Hydrolysis raises G, or Gibbs free energy.
3. C) Hydrolysis decreases entropy and is exergonic.
4. D) Hydrolysis increases entropy and is endergonic

A) Hydrolysis increases entropy and is exergonic.

Why is ATP an important molecule in metabolism?

1. A) Its hydrolysis provides an input of free energy for exergonic reactions.
2. B) It provides energy coupling between exergonic and endergonic reactions.
3. C) Its terminal phosphate group contains a strong covalent bond that, when hydrolyzed, releases free energy.
4. D) Its terminal phosphate bond has higher energy than the other two phosphate bonds.

B) It provides energy coupling between exergonic and endergonic reactions.

The process of photosynthesis probably originated _____.

1. A) in plants
2. B) in prokaryotes
3. C) in fungi
4. D) three separate times during evolution

B) in prokaryotes

In autotrophic bacteria, where is chlorophyll located?

1. A) in chloroplast membranes
2. B) in the ribosomes
3. C) in the nucleoid
4. D) in the infolded plasma membrane

D) in the infolded plasma membrane

Why are there several structurally different pigments in the reaction centers of photosystems?

1. A) Excited electrons must pass through several pigments before they can be transferred to electron acceptors of the electron transport chain.
2. B) This arrangement enables the plant to absorb light energy of a variety of wavelengths.
3. C) They enable the plant to absorb more photons from light energy, all of which are at the same wavelength.
4. D) They enable the reaction center to excite electrons to a higher energy level.

B) This arrangement enables the plant to absorb light energy of a variety of wavelengths.

A G-protein receptor with GTP bound to it _____.

1. will use cGMP as a second messenger
2. is in its active state
3. directly affects gene expression
4. signals a protein to maintain its shape and conformation

B. is in its active state

One of the major categories of receptors in the plasma membrane reacts by forming dimers, adding phosphate groups, and then activating relay proteins. Which type does this?
A) G protein-coupled receptors
B) ligand-gated ion channels
C) steroid receptors
D) receptor tyrosine kinases

D) receptor tyrosine kinases

In general, a signal transmitted via phosphorylation of a series of proteins
A) results in a conformational change to each protein.
B) requires binding of a hormone to a cytosol receptor.
C) cannot occur in yeasts because they lack protein phosphatases.
D) requires phosphorylase activity.

A) results in a conformational change to each protein.

An inhibitor of which of the following could be used to block the release of calcium from the endoplasmic reticulum?
A) tyrosine kinases
B) serine/threonine kinases
C) phosphodiesterase
D) phospholipase C

D) phospholipase C

Binding of a signaling molecule to which type of receptor leads directly to a change in the distribution of ions on opposite sides of the membrane?
A) receptor tyrosine kinase
B) G protein-coupled receptor
C) phosphorylated receptor tyrosine kinase dimer
D) ligand-gated ion channel

D) ligand-gated ion channel

Which of the following describes the events of apoptosis?
A) The cell dies, it is lysed, its organelles are phagocytized, and its contents are recycled.
B) Its DNA and organelles become fragmented, it dies, and it is phagocytized.
C) The cell dies and the presence of its fragmented contents stimulates nearby cells to divide.
D) The cell's DNA and organelles become fragmented, the cell shrinks and forms blebs, and the cell self-digests.

D) The cell's DNA and organelles become fragmented, the cell shrinks and forms blebs, and the cell self-digests.

In eukaryotic cells, chromosomes are composed of _____.

1. A) DNA and RNA
2. B) DNA only
3. C) DNA and proteins
4. D) DNA and phospholipids

C) DNA and proteins

Metaphase is characterized by _____.

1. A) aligning of chromosomes on the equator
2. B) splitting of the centromeres
3. C) cytokinesis
4. D) separation of sister chromatids

A) aligning of chromosomes on the equator

Which of the following is true of a species that has a chromosome number of 2n = 16?

1. A) The species is diploid with 32 chromosomes per cell.
2. B) The species has 16 sets of chromosomes per cell.
3. C) Each diploid cell has eight homologous pairs.
4. D) A gamete from this species has four chromosomes.

C) Each diploid cell has eight homologous pairs.

Homologous chromosomes _____.

1. A) are identical
2. B) carry information for the same traits
3. C) carry the same alleles
4. D) align on the metaphase plate in meiosis II

B) carry information for the same traits

Which of the following defines a genome?

1. A) the complete set of an organism's polypeptides
2. B) the complete set of a species' polypeptides
3. C) a karyotype
4. D) the complete set of an organism's genes and other DNA sequences

D) the complete set of an organism's genes and other DNA sequences

The human X and Y chromosomes _____.

1. A) are both present in every somatic cell of males and females
2. B) are the same size and have the same number of genes
3. C) include genes that determine an individual's sex
4. D) are called autosomes

C) include genes that determine an individual's sex

Genetic variation leads to genetic diversity in populations and is the raw material for evolution. Biological systems have multiple processes, such as reproduction, that affect genetic variation. They are evolutionarily conserved and shared by various organisms.

Which statement best represents the connection between reproduction and evolution?

1. A) Plants that use sexual reproduction are rare since this type of reproduction in plants does not contribute to genetic diversity.
2. B) In order to increase genetic diversity for evolution in sexually reproducing organisms, mutations must occur in the zygote after fertilization.
3. C) Since prokaryotic organisms reproduce asexually, there is no mechanism for them to add genetic diversity for evolution.
4. D) Sexual reproduction increases genetic variation because random mutations can be shuffled between organisms.

D) Sexual reproduction increases genetic variation because random mutations can be shuffled between organisms.

In trying to determine whether DNA or protein is the genetic material, Hershey and Chase made use of which of the following facts?
A) DNA contains sulfur, whereas protein does not.
B) DNA contains phosphorus, whereas protein does not.
C) DNA contains nitrogen, whereas protein does not.
D) DNA contains purines, whereas protein includes pyrimidines.

A particular triplet of bases in the template strand of DNA is 5' AGT 3'. The corresponding codon for the mRNA transcribed is _____.

1. A) UCA
2. B) UGA
3. C) TCA
4. D) ACU

B. Dna contains phosphorus, whereas protein does not

A.UCA

What is the role of DNA ligase in the elongation of the lagging strand during DNA replication?
A) It synthesizes RNA nucleotides to make a primer.
B) It catalyzes the lengthening of telomeres.
C) It joins Okazaki fragments together.
D) It unwinds the parental double helix.
E) It stabilizes the unwound parental DNA.

C) It joins Okazaki fragments together

Eukaryotic telomeres replicate differently than the rest of the chromosome. This is a consequence of which of the following?
A) the evolution of telomerase enzyme
B) DNA polymerase that cannot replicate the leading strand template to its 5' end
C) gaps left at the 5' end of the lagging strand
D) gaps left at the 3' end of the lagging strand because of the need for a primer

C) gaps left at the 5' end of the lagging strand

If a cell were unable to produce histone proteins, which of the following would be a likely effect?

A) There would be an increase in the amount of "satellite" DNA produced during centrifugation.
B) The cell's DNA couldn't be packed into its nucleus.
C) Spindle fibers would not form during prophase.
D) Amplification of other genes would compensate for the lack of histones.

B) The cell's DNA couldn't be packed into its nucleus.

Why do histones bind tightly to DNA?
A) Histones are positively charged, and DNA is negatively charged.
B) Histones are negatively charged, and DNA is positively charged.
C) Both histones and DNA are strongly hydrophobic.
D) Histones are covalently linked to the DNA.

A) Histones are positively charged, and DNA is negatively charged.

Codons are part of the molecular structure of _____.

1. A) a protein
2. B) mRNA
3. C) tRNA
4. D) rRNA

B) mRNA

A ribozyme is _____.

1. A) a catalyst that uses RNA as a substrate
2. B) an RNA with catalytic activity
3. C) an enzyme that catalyzes the association between the large and small ribosomal subunits
4. D) an enzyme that synthesizes RNA as part of the transcription process

B) an RNA with catalytic activity

Alternative RNA splicing _____.

1. A) is a mechanism for increasing the rate of translation
2. B) can allow the production of proteins of different sizes and functions from a single mRNA
3. C) can allow the production of similar proteins from different RNAs
4. D) increases the rate of transcription

1. B) can allow the production of proteins of different sizes and functions from a single mRNA

In the process of transcription, _____.

1. A) DNA is replicated
2. B) RNA is synthesized
3. C) proteins are synthesized
4. D) mRNA attaches to ribosomes

B) RNA is synthesized

A signal peptide _____.

1. A) directs an mRNA molecule into the cisternal space of the ER
2. B) terminates translation of messenger RNA
3. C) helps target a protein to the ER
4. D) signals the initiation of transcription

C) helps target a protein to the ER

How might a single base substitution in the sequence of a gene affect the amino acid sequence of a protein encoded by the gene, and why?

1. A) Only a single amino acid could change, because the reading frame is unaffected.
2. B) The amino acid sequence would be substantially altered, because the reading frame would change with a single base substitution.
3. C) All amino acids following the substitution would be affected, because the reading frame would be shifted

A) Only a single amino acid could change, because the reading frame is unaffected.

A single base substitution mutation is least likely to be deleterious when the base change results in _____.

1. A) a stop codon
2. B) a codon that specifies the same amino acid as the original codon
3. C) an amino acid substitution that alters the tertiary structure of the protein
4. D) an amino acid substitution at the active site of an enzyme

B) a codon that specifies the same amino acid as the original codon

A nonsense mutation in a gene _____.

1. A) changes an amino acid in the encoded protein
2. B) has no effect on the amino acid sequence of the encoded protein
3. C) introduces a premature stop codon into the mRNA
4. D) alters the reading frame of the mRNA

C) introduces a premature stop codon into the mRNA

Post-translational modifications of proteins may include the _____.

1. A) removal of introns
2. B) addition of a 5’ cap
3. C) addition of a poly-A tail
4. D) addition of carbohydrates to form a glycoprotein

D) addition of carbohydrates to form a glycoprotein

Transcription in eukaryotes requires which of the following in addition to RNA polymerase?

1. A) start and stop codons
2. B) ribosomes and tRNA
3. C) several transcription factors
4. D) aminoacyl-tRNA synthetase

C) several transcription factors

Genomic imprinting, DNA methylation, and histone acetylation are all examples of
A) genetic mutation.
B) chromosomal rearrangements.
C) karyotypes.
D) epigenetic phenomena.
E) translocation.

D) epigenetic phenomena

Which of the following is characteristic of the lytic cycle?
A) Many bacterial cells containing viral DNA are produced.
B) Viral DNA is incorporated into the host genome.
C) The viral genome replicates without destroying the host.
D) A large number of phages are released at a time.
E) The virus-host relationship usually lasts for generations

D) A large number of phages are released at a time.

Which of the following statements describes the lysogenic cycle of lambda (λ) phage?
A) After infection, the viral genes immediately turn the host cell into a lambda-producing factory, and the host cell then lyses.
B) Most of the prophage genes are activated by the product of a particular prophage gene.
C) The phage genome replicates along with the host genome.
D) Certain environmental triggers can cause the phage to exit the host genome, switching from the lytic to the lysogenic. .

C) The phage genome replicates along with the host genome.