Elephants are not the most dominant species in African grasslands, yet they influence
community structure. The grasslands contain scattered woody plants, but they are kept
in check by the uprooting activities of the elephants. Take away the elephants, and the
grasslands convert to forests or to shrublands. The newly growing forests support fewer
species than the previous grasslands. Which of the following describes why elephants
are the keystone species in this scenario?
A) Elephants exhibit a disproportionate influence on the structure of the community
relative to their abundance.
B) Grazing animals depend upon the elephants to convert forests to grassland.
C) Elephants are the biggest herbivore in this community.
D) Elephants help other populations survive by keeping out many of the large African
predators.
After mixing a heat-killed, phosphorescent (light-emitting) strain of bacteria with a
living, nonphosphorescent strain, you discover that some of the living cells are now
phosphorescent. Which observation(s) would provide the best evidence that the ability
to phosphoresce is a heritable trait?
A) evidence that DNA was passed from the heat-killed strain to the living strain
B) evidence that protein passed from the heat-killed strain to the living strain
C) especially bright phosphorescence in the living strain
D) phosphorescence in descendants of the living cells
As a research scientist, you measure the amount of ATP and NADPH consumed by the
Calvin cycle in 1 hour. You find that 30,000 molecules of ATP were consumed, but only
20,000 molecules of NADPH were consumed. Where did the extra ATP molecules
come from?
A) photosystem II
B) photosystem I
C) cyclic electron flow
D) linear electron flow
Arthropod exoskeletons and mollusk shells both _____.
A) completely replace the hydrostatic skeleton
B) are secreted by the mantle
C) help retain moisture in terrestrial habitats
D) are comprised of the polysaccharide chitin
Proto-oncogenes _____.
A) normally suppress tumor growth
B) are produced by somatic mutations induced by carcinogenic substances
C) stimulate normal cell growth and division
D) are underexpressed in cancer cells
Which of the following statements is true about certainty of paternity?
A) Certainty of paternity is high in most species with internal fertilization because the
acts of mating and birth are separated by time.
B) Certainty of paternity is low when males guard females they have mated.
C) Certainty of paternity is low when egg laying and mating occur together, as in
external fertilization.
D) Paternal behavior exists because it has been reinforced over generations by natural
selection.
Managing southeastern forests specifically for the red-cockaded woodpecker _____.
A) required the growth of a dense understory of trees and shrubs
B) contributed to greater abundance and diversity of other forest bird species
C) caused other species of songbird to decline
D) involved strict fire suppression measures
In individual insects of some species, whole chromosomes that carry larval genes are
eliminated from the genomes of somatic cells at the time of metamorphosis. A
consequence of this occurrence is that _____.
A) we could not clone a larva from the somatic cells of such an adult insect
B) such species must reproduce only asexually
C) the descendants of these adults do not include a larval stage
D) metamorphosis can no longer occur among the descendents of such adults
Five new individuals were added to this small population in 1986 and ten more were
added between 1990-1994. According to the figure above, what occurred in this
population after these additions?
A) The population increased exponentially.
B) The population increased in overall numbers.
C) The population growth rate increased.
D) The population continued to decline
The cells lining the air sacs in the lungs make up a _____.
A) simple squamous epithelium
B) stratified squamous epithelium
C) pseudostratified ciliated columnar epithelium
D) simple columnar epithelium
The hydrostatic skeleton of the earthworm allows it to move around in its environment
by _____.
A) walking on its limbs
B) swimming with its setae
C) using peristaltic contractions of its circular and longitudinal muscles
D) alternating contractions and relaxations of its flagella
When a plant cell, such as one from a rose stem, is submerged in a very hypotonic
solution, what is likely to occur?
A) The cell will burst.
B) Plasmolysis will shrink the interior.
C) The cell will become flaccid.
D) The cell will become turgid.
The following questions refer to this phylogenetic tree, depicting the origins of life and
of the three domains. Horizontal lines indicate instances of gene or genome transfer.
A possible phylogenetic tree for the three domains of life.
Which portion of the figure above may ultimately be better depicted as a “ring”?
A) the bacterial lineage
B) the archaean lineage
C) the eukaryotic lineage
D) the trunk of the tree
Use the figure below to answer the following question(s).
Which extinct species should be the best candidate to serve as the outgroup for the
clade whose common ancestor occurs at position 2 in the figure above?
A) A
B) B
C) C
D) E
Which of the following is the meaning of the chromosome theory of inheritance as
expressed in the early twentieth century?
A) Individuals inherit particular chromosomes attached to genes.
B) Mendelian genes are at specific loci on the chromosome and, in turn, segregate
during meiosis.
C) No more than a single pair of chromosomes can be found in a healthy normal cell.
D) Natural selection acts on certain chromosome arrays rather than on genes.
Which of the following primarily enters a plant somewhere other than through the
roots?
A) carbon dioxide
B) nitrogen
C) potassium
D) water
Which two genera have members that can evade the human immune system by
frequently changing their surface proteins?
1. Plasmodium
2. Trichomonas
3. Paramecium
4. Trypanosoma
5. Entamoeba
A) 1 and 4
B) 2 and 3
C) 2 and 4
D) 4 and 5
Van der Waals interactions may result when _____.
A) electrons are not symmetrically distributed in a molecule
B) molecules held by ionic bonds react with water
C) two polar covalent bonds react
D) a hydrogen atom loses an electron
In a hypothetical situation, a bacterium lives on the surface of a leaf, where it obtains
nutrition from the leaf’s nonliving, waxy covering while inhibiting the growth of other
microbes that are plant pathogens. If this bacterium gains access to the inside of a leaf,
however, it causes a fatal disease in the plant. Once the plant dies, the bacterium and its
offspring decompose the plant. What is the correct sequence of ecological roles played
by the bacterium in the situation described here?
1. nutrient recycler
2. mutualist
3. commensal
4. pathogen
5. primary producer
A) 1, 3, 4
B) 2, 3, 4
C) 2, 4, 1
D) 1, 2, 5
You find what you believe is a new species of animal. Which of the following
characteristics would enable you to argue that it is more closely related to a flatworm
than it is to a roundworm?
A) It is a suspension feeder.
B) It has no coelom.
C) It is shaped like a worm.
D) It has a mouth and an anus.
Sharks live in seawater. Their tissues are isotonic to seawater, but their concentrations
of sodium ions, potassium ions, and chloride ions in cells and extracellular fluids are
similar to those of freshwater fishes. How is that possible?
A) Urea and trimethylamine oxide contribute to intra- and extracellular osmolarity in
shark tissues.
B) Metabolic intermediates of sharks tie up intracellular chloride and potassium ions.
C) Their blood is hypotonic to their tissues.
D) They excrete large quantities of electrolytes.
The following table depicts characteristics of five prokaryotic species (A-E). Use the
information in the table to answer the question(s) below
Which species is most likely to be found in sewage treatment plants and in the guts of
cattle?
A) species A
B) species B
C) species C
D) species D
Which of the following correctly describes all chemical equilibrium?
A) Forward and reverse reactions continue with no net effect on the concentrations of
the reactants and products.
B) Concentrations of products are higher than the concentrations of the reactants.
C) There are equal concentrations of products and reactants while forward and reverse
reactions continue.
D) There are equal concentrations of reactants and products, and the reactions have
stopped.
Diploid nuclei of the ascomycete, Neurospora crassa, contain 14 chromosomes. A
single diploid cell in an ascus will undergo one round of meiosis, followed in each of
the daughter cells by one round of mitosis, producing a total of eight ascospores.
If a single, diploid G2 nucleus in an ascus contains 400 nanograms (ng) of DNA, then a
single ascospore nucleus of this species should contain how much DNA (ng), carried on
how many chromosomes?
A) 100, carried on 7 chromosomes
B) 100, carried on 14 chromosomes
C) 200, carried on 7 chromosomes
D) 200, carried on 14 chromosomes
Early investigators thought the oxygen produced by photosynthetic plants came from
carbon dioxide. In fact, it comes from _____.
A) water
B) glucose
C) air
D) electrons from NADPH
A researcher found a beautiful plant while traveling in Alaska and collected its seeds.
When she came back to Florida, she soaked some seeds in pure water and some in
water with a hormone. When she put the seeds in soil to grow, only the seeds that had
been soaked with the hormone germinated. The hormone most likely was _____.
A) gibberellin
B) abscisic acid (ABA)
C) auxin
D) ethylene
“Marine cone snails from the genus Conus are estimated to consist of up to 700 species.
These predatory molluscs have devised an efficient venom apparatus that allows them
to successfully capture polychaete worms, other molluscs, or in some cases fish as their
primary food sources. conotoxins from Australian species of Conus have the capacity to
inhibit specifically the nicotinic acetylcholine receptors in higher animals.” (B. G.
Livett, K. R. Gayler, and Z. Khalil. 2004. Drugs from the sea: Conopeptides as potential
therapeutics. Current Medicinal Chemistry 11:1715-23.)
Refer to the paragraph above on the venom of marine core snails. This particular
conotoxin inhibits acetylcholine receptors that are located _____.
A) along the motor neuron axon
B) on motor neuron dendrites
C) on the presynaptic membrane of the neuromuscular junction
D) on the postsynaptic membrane, on the muscle cell
The crucian carp (Carassius carassius) is a Northern European freshwater fish often
inhabiting ponds that become hypoxic (have reduced oxygen levels) and even anoxic
(have no oxygen) when the surface freezes during the winter. Surprisingly, when
oxygen levels are normal, these fish lack the lamellae that provide a large surface area
for gas exchange between water and blood: their gills are smooth. Yet when the level of
oxygen in the water falls, the gill morphology undergoes a change: packing cells stop
dividing and programmed cell death is induced, exposing gill lamellae that were buried
in other tissue. With lamellae exposed, the gills have increased surface area for gas
exchange. These changes in gill lamellar profile are reversible: investigators observed
that the gills return to their normal structure within seven days after returning the fish to
well-oxygenated water. (Jrund Sollid, Paula De Angelis, Kristian Gundersen, and Gran
E. Nilsson. 2003. Hypoxia induces adaptive and reversible gross morphological
changes in crucian carp gills. Journal of Experimental Biology 206:3667-73.)
Refer to the paragraph on crucian carp. Gills serve multiple functions in fish in addition
to gas exchange. Given the large surface area of gills with lamellae, what is the most
likely explanation for why crucian carp cover protruding lamellae in their gills when
levels of oxygen are normal?
A) to prevent loss of heat to the surrounding water
B) to prevent loss of ions to the surrounding water
C) to prevent protein loss to the surrounding water
D) to prevent loss of oxygen to the surrounding water
The lakes of northern Minnesota are home to many similar species of damselflies of the
genus Enallagma. These species have apparently undergone speciation from ancestral
stock since the last glacial retreat about ten thousand years ago. Sequencing which of
the following would probably be most useful in sorting out evolutionary relationships
among these closely related species?
A) conserved regions of nuclear DNA
B) mitochondrial DNA
C) amino acids in proteins
D) ribosomal RNA
When Thomas Hunt Morgan crossed his red-eyed F1 generation flies to each other, the
F2 generation included both red- and white-eyed flies. Remarkably, all the white-eyed
flies were male. What was the explanation for this result?
A) The gene involved is on the Y chromosome.
B) The gene involved is on the X chromosome.
C) The gene involved is on an autosome, but only in males.
D) Other male-specific factors influence eye color in flies.
An ectopic pregnancy occurs when a fertilized egg implants somewhere other than in
the lining of the uterus. Usually it implants in the oviduct. Which of the following
would be the most likely explanation for such a pregnancy being unsuccessful?
A) The orientation of the baby would be sideways.
B) Human chorionic gonadotropin (hCG) cannot be produced in the oviduct.
C) The lining of the oviduct is unable to support the developing fetus.
D) The necessary hormones cannot reach the developing fetus in the oviduct.