To measure the population of lake trout in a 250-hectare lake, 400 individual trout were
netted and marked with a fin clip, then returned to the lake. The next week, the lake was
netted again, and out of the 200 lake trout that were caught, 50 had fin clips. Using the
mark-recapture estimate, the lake trout population size could be closest to which of the
following?
A) 200
B) 400
C) 1,600
D) 80,000
Suppose you are provided with an actively dividing culture of E. coli bacteria to which
radioactive thymine has been added. What would happen if a cell replicates once in the
presence of this radioactive base?
A) One of the daughter cells, but not the other, would have radioactive DNA.
B) Neither of the two daughter cells would be radioactive.
C) All four bases of the DNA would be radioactive.
D) DNA in both daughter cells would be radioactive.
Rose-picker’s disease is caused by the yeast Sporothrix schenkii (S. schenkii). The yeast
grows on the exteriors of rose-bush thorns. If a human gets pricked by such a thorn, the
yeasts can be introduced under the skin. The yeasts then assume a hyphal morphology
and grow along the interiors of lymphatic vessels until they reach a lymph node. This
often results in the accumulation of pus in the lymph node, which subsequently
ulcerates through the skin surface and then drains.
Humans have immune systems in which lymph nodes are important, because many
phagocytes and lymphocytes reside there. Given that a successful infection by S.
schenkii damages lymph nodes themselves, which of the following is most probable?
A) The hyphae secrete antibiotics, which increases the ability of the infected human to
tolerate the fungus.
B) Their conversion from yeast to hyphal morphology allows such fast growth that the
body’s defenses are at least temporarily overwhelmed.
C) Defensive cells of humans cannot detect foreign cells that are covered with cell
walls composed of cellulose.
D) Given that most fungal pathogens attack plants, human defenses are simply not
adapted to seek out and destroy fungi.
Water molecules are attracted to one another by _____.
A) nonpolar covalent bonds
B) ionic bonds
C) hydrogen bonds
D) hydrophobic interactions
How many electron pairs are shared between carbon atoms in a molecule that has the
formula C2H4?
A) 1
B) 2
C) 3
D) 4
On the basis of their morphologies, how might Linnaeus have classified the Hawaiian
silverswords? Linnaeus would have _____.
A) placed them all in the same species.
B) classified them the same way that modern botanists do.
C) placed more of them in different genera than modern botanists do.
D) used evolutionary relatedness as the primary criterion for their classification.
Which characteristic is common to all the modern representatives of all major reptilian
lineages (turtles, lepidosaurs, crocodilians, and birds)?
A) presence of teeth
B) presence of four walking limbs
C) ectothermy
D) presence of a notochord
Mitochondrial DNA is primarily involved in coding for proteins needed for protein
complexes of the electron transport chain and ATP synthase. Therefore, mutations in
mitochondrial genes would most affect _____.
A) DNA synthesis in cells of the immune system
B) the movement of oxygen into erythrocytes
C) generation of ATP in muscle cells
D) the storage of urine in the urinary bladder
Which of the following organs is correctly paired with its function?
A) stomach protein digestion
B) large intestine bile production
C) small intestine starch digestion
D) pancreas starch digestion
Why does ice float in liquid water?
A) The high surface tension of liquid water keeps the ice on top.
B) The ionic bonds between the molecules in ice prevent the ice from sinking.
C) Stable hydrogen bonds keep water molecules of ice farther apart than water
molecules of liquid water.
D) The crystalline lattice of ice causes it to be denser than liquid water.
Several of the different globin genes are expressed in humans, but at different times in
development. What mechanism could allow for this?
A) exon shuffling
B) pseudogene activation
C) differential translation of mRNAs
D) differential gene regulation over time
Which of the following types of reactions would decrease the entropy within a cell?
A) anabolic reactions
B) hydrolysis
C) digestion
D) catabolic reactions
Long-term studies of Belding’s ground squirrels show that immigrants move nearly 2
kilometers from where they are born and become 1%-8% of the males and 0.7%-6% of
the females in other populations. On an evolutionary scale, why is this significant?
A) These immigrants make up for the deaths of individuals, keeping the other
populations’ size stable.
B) These immigrants provide a source of genetic diversity for the other populations.
C) Those individuals that emigrate to these new populations are looking for less
crowded conditions with more resources.
D) Gradually, the populations of ground squirrels will move from a clumped to a
uniform population pattern of dispersion.
In a comparison of birds and mammals, having four limbs is _____.
A) a shared ancestral character
B) a shared derived character
C) a character useful for distinguishing birds from mammals
D) an example of analogy rather than homology
Consider the following reaction at equilibrium: What would be
the effect of adding additional H2CO3?
A) It would drive the equilibrium dynamics to the right.
B) It would drive the equilibrium dynamics to the left.
C) Nothing would happen, because the reactants and products are in equilibrium.
D) The amounts of CO2 and H2O would decrease.
The figure above shows the structures of glucose and fructose. These two molecules are
_____.
A) isotopes
B) enantiomers
C) cis-trans isomers
D) structural isomers
Which of the following is (are) true of natural selection?
A) It requires genetic variation.
B) It results in descent with modification.
C) It involves differential reproductive success.
D) It requires genetic variation, results in descent with modification, and involves
differential reproductive success.
What results from an unequal sharing of electrons between atoms?
A) a nonpolar covalent bond
B) a polar covalent bond
C) an ionic bond
D) a hydrophobic interaction
RNAi methodology uses double-stranded pieces of RNA to trigger breakdown of a
specific mRNA or inhibit its translation. For which of the following might this
technique be useful?
A) to decrease the production from a harmful mutated gene
B) to destroy an unwanted allele in a homozygous individual
C) to form a knockout organism that will not pass the deleted sequence to its progeny
D) to raise the concentration of a desired protein
The free energy for the oxidation of glucose to CO2 and water is -686 kcal/mol and the
free energy for the reduction of NAD+ to NADH is +53 kcal/mol. Why are only two
molecules of NADH formed during glycolysis when it appears that as many as a dozen
could be formed?
A) Most of the free energy available from the oxidation of glucose is used in the
production of ATP in glycolysis.
B) Glycolysis is a very inefficient reaction, with much of the energy of glucose released
as heat.
C) Most of the free energy available from the oxidation of glucose remains in pyruvate,
one of the products of glycolysis.
D) There is no CO2 or water produced as products of glycolysis.
Amoebae move by crawling over a surface (cell crawling), which involves _____.
A) growth of actin filaments to form bulges in the plasma membrane
B) setting up microtubule extensions that vesicles can follow in the movement of
cytoplasm
C) reinforcing the pseudopod with intermediate filaments
D) cytoplasmic streaming
In chemiosmosis, what is the most direct source of energy that is used to convert ADP +
i to ATP?
A) energy released as electrons flow through the electron transport system
B) energy released from substrate-level phosphorylation
C) energy released from movement of protons through ATP synthase, down their
electrochemical gradient
D) No external source of energy is required because the reaction is exergonic.
Suppose you traveled back in time and located the first animals to have evolved
feathers. You found that these animals were tree-dwelling ectotherms, able to run
quickly but unable to fly. You also noticed that only males had feathers. Which
hypothesis of feather evolution would these data most support? Feathers initially
evolved in a role associated with _____.
A) flight
B) insulation
C) sexual selection
D) gliding
Altering patterns of gene expression in prokaryotes would most likely serve an
organism’s survival by _____.
A) organizing gene expression, so that genes are expressed in a given order
B) allowing each gene to be expressed an equal number of times
C) allowing an organism to adjust to changes in environmental conditions
D) allowing environmental changes to alter a prokaryote’s genome
In glycolysis, for each molecule of glucose oxidized to pyruvate _____.
A) two molecules of ATP are used and two molecules of ATP are produced.
B) two molecules of ATP are used and four molecules of ATP are produced.
C) four molecules of ATP are used and two molecules of ATP are produced.
D) two molecules of ATP are used and six molecules of ATP are produced.
A researcher took water in which a Jl population had been thriving, filtered the water to
remove all bacterial cells, and then applied the water to the skins of adult amphibians to
see if there would subsequently be a reduced infection rate by Bd when frog skins were
inoculated with Bd. For which of the following hypotheses is the procedure described a
potential test?
A) the hypothesis that a toxin secreted by Jl cells kills Bd cells when both are present
together on frog skin
B) the hypothesis that Jl cells infect and kill Bd cells when both are present together on
frog skin
C) the hypothesis that Jl outcompetes Bd when both are present together on a frog’s skin
D) the hypothesis that the presence of Jl on frog skin causes a skin reaction that
prevents attachment by Bd cells
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.
Motor neurons release the neurotransmitter acetylcholine (ACh) and
acetylcholinesterase degrades ACh in the synapse. If a neurophysiologist applies
onchidal (a naturally occurring acetylcholinesterase inhibitor produced by the mollusc
Onchidella binneyi) to a synapse, what would you expect to happen?
A) paralysis of muscle tissue
B) convulsions due to constant muscle stimulation
C) decrease in the frequency of action potentials
D) no effect
A series of enzymes catalyze the reaction X → Y → Z → A. Product A binds to the
enzyme that converts X to Y at a position remote from its active site. This binding
decreases the activity of the enzyme.
What is substance X?
A) an allosteric inhibitor
B) a substrate
C) an intermediate
D) the product
Which of the following is a protein synthesized at specific times during the cell cycle
that associates with a kinase to form a catalytically active complex?
A) PDGF
B) MPF
C) cyclin
D) Cdk