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In some rare salamander species, all individuals are females. Reproduction relies on
those females having access to sperm from males of another species. However, the
resulting embryos receive no genetic contribution from the males. In this case, the
sperm appear to be used only for _____.
A) morphogenesis
B) egg activation
C) cell differentiation
D) the creation of a diploid cell
When wefirst see chiasmata under a microscope, we know that _____.
A) meiosis II has occurred
B) anaphase II has occurred
C) prophase I is occurring
D) separation of homologs has occurred
Estrogens found in the environment have raised concerns about effects on reproductive
health of animals. Researchers studied the effects that estrogens in the water have on
sexual differentiation in zebrafish. They exposed embryo-larval (0-21 days
post-hatching), juvenile (21-42 days post-hatching), and adult (over 200 days
post-hatching) fish to three concentrations of 17β-estradiol (5, 25, and 100
nanograms/liter) that are within the range of concentrations found in water leaving
sewage treatment plants in different countries. They then examined the proportion of
males and females when the fish exposed at embryo-larval and juvenile stages reached
adulthood. Embryo-larval stage fish that had been exposed to 100 ng/l 17β-estradiol
resulted in adult populations that had substantially more females than males compared
to control groups. Embryo-larval fish that had been exposed to 5 and 25 ng/l of
17β-estradiol did not show a statistically significant shift in the proportion of females.
(Brion, F., C. R. Tyler, X. Palazzi, B. Laillet, J. M. Porcher, J. Garric, and P.
Flammarion. 2004. Impacts of 17β-estradiol, including environmentally relevant
concentrations, on reproduction after exposure during embryo-larval-, juvenile-, and
adult-life stages in zebrafish (Danio rerio). Aquatic Toxicology 68:193-217.)
Refer to the paragraph on the effects of estrogens in the environment. You are assigned
to write the report to the Environmental Protection Agency, which needs to decide what
level of 17β-estradiol to permit in sewage output. You do not want to make the level
any lower than necessary, because it requires substantial additional money for the extra
treatment of sewage. Given the data presented above, what level of 17β-estradiol would
you suggest is safe to prevent feminization of fish?
A) 2.5 ng/l
B) 12.5 ng/l
C) 25 ng/l
D) 100 ng/l
Increased activity in the sympathetic nervous system leads to _____.
A) decreased heart rate
B) increased secretion by the pancreas
C) increased contractions of the stomach
D) relaxation of the airways in the lungs
Scarlet gilia (Ipomopsis aggregata) usually has red flowers in an inflorescence of up to
250 flowers. In certain populations in the Arizona mountains, however, the flowers
range from red to pink to white. In early summer, most of the flowers were red. Six to
eight weeks later, the same individual plants were still present; the flowers ranged from
pink to white, and few red flowers were present. The major pollinators early in the
season were two species of hummingbirds active during the day; they emigrated to
lower elevations, and the major pollinator later in the season was a hawk moth (a type
of moth). The hawk moth was most active at sunset and later, and it preferred light pink
to white flowers after dark. When hummingbirds were present, more red flowers than
white flowers produced fruit. When only hawk moths were present, more white flowers
produced fruit (K. N. Paige and T. G. Whitham. 1985. Individual and population shifts
in flower color by scarlet gilia: A mechanism for pollinator tracking. Science
227:315-17).
Refer to the paragraph on scarlet gilia. Some plants changed their flowers to lighter
colors, and some retained the same darker color all season. Which plants do you expect
produced more fruit?
A) those that changed their color to a lighter shade
B) those that stayed darker
C) the same numbers of fruit on both
The following questions refer to the generalized life cycle for land plants shown in the
figure below. Each number within a circle or square represents a specific plant or plant
part, and each number over an arrow represents either meiosis, mitosis, or fertilization.
In the figure above, meiosis is most likely to be represented by which number(s)?
A) 2
B) 4
C) 2 and 8
D) 10 and 12
Giardia intestinalis is an intestinal parasite of humans and other mammals that causes
intestinal ailments in most people who ingest the cysts. Upon ingestion, each cyst
releases two motile cells, called trophozoites. These attach to the small intestine's lining
via a ventral adhesive disk. The trophozoites anaerobically metabolize glucose from the
host's intestinal contents to produce ATP. Reproduction is completely asexual, occurring
by longitudinal binary fission of trophozoites, with each daughter cell receiving two
haploid nuclei (n = 5). A trophozoite will often encyst as it passes into the large
intestine by secreting around itself a case that is resistant to cold, heat, and dehydration.
Infection usually occurs by drinking untreated water that contains cysts.
The cysts of Giardia function most like the _____.
A) mitochondria of ancestral diplomonads
B) nuclei of archaeans
C) endospores of bacteria
D) capsids of viruses
In photosynthetic cells, synthesis of ATP by the chemiosmotic mechanism occurs
during _____.
A) photosynthesis only
B) respiration only
C) photosynthesis and respiration
D) neither photosynthesis nor respiration
Theodor W. Engelmann illuminated a filament of algae with light that passed through a
prism, thus exposing different segments of algae to different wavelengths of light. He
added aerobic bacteria and then noted in which areas the bacteria congregated. He
noted that the largest groups were found in the areas illuminated by the red and blue
light.
What did Engelmann conclude about the congregation of bacteria in the red and blue
areas?
A) Bacteria congregated in these areas due to an increase in the temperature of the red
and blue light.
B) Bacteria congregated in these areas because these areas had the most oxygen being
released.
C) Bacteria are attracted to red and blue light and thus these wavelengths are more
reactive than other wavelengths.
D) Bacteria congregated in these areas due to an increase in the temperature caused by
an increase in photosynthesis.
In the hypothesis that C. stellatus (a species of barnacle) is competitively excluded from
the lower intertidal zone by B. balanoides (another species of barnacle), what could be
concluded about the two species?
A) The fundamental and realized niches of B. balanoides and C. stellatus are identical.
B) The fundamental and realized niches of B. balanoides and C. stellatus are different.
C) The fundamental and realized niches of B. balanoides are different, but the
fundamental and realized niches of C. stellatus are identical.
D) The fundamental and realized niches of B. balanoides are identical, but the
fundamental and realized niches of C. stellatus are different.
Flying insects typically _____.
A) decrease metabolism as much as 200-fold during flight
B) switch from diffusion of tracheal gases to active transport during flight
C) utilize high numbers of mitochondria in flight muscles
D) generate fuel molecules from catabolism of carbon dioxide
Which of the following locations are major reservoirs for carbon for the carbon cycle?
I) atmosphere
II) sediments and sedimentary rocks
III) fossilized plant and animal remains (coal, oil, and natural gas)
IV) plant and animal biomass
A) only I and III
B) only II and IV
C) only II, III, and IV
D) I, II, III, and IV
Single-celled Paramecium live in pond water (a hypotonic environment). They have a
structural feature, a contractile vacuole, which enables them to osmoregulate. If you
observed them in the following solutions, at which sucrose concentration (in
millimolars, mM) would you expect the contractile vacuole to be most active?
A) 0.0 mM sucrose
B) 0.05 mM saline
C) 0.08 mM sucrose
D) 1.0 mM saline
The Brazil nut tree, Bertholletia excels (n = 17), is native to tropical rain forests of
South America. It is a hardwood tree that can grow to over 50 meters tall, is a source of
high-quality lumber, and is a favorite nesting site for harpy eagles. As the rainy season
ends, tough-walled fruits, each containing 8-25 seeds (Brazil nuts), fall to the forest
floor. Brazil nuts are composed primarily of endosperm. About $50 million worth of
nuts are harvested each year. Scientists have discovered that the pale yellow flowers of
Brazil nut trees cannot fertilize themselves and admit only female orchid bees as
pollinators. The agouti (Dasyprocta spp.), a cat-sized rodent, is the only animal with
teeth strong enough to crack the hard wall of Brazil nut fruits. It typically eats some of
the seeds, buries others, and leaves still others inside the fruit, which moisture can now
enter. The uneaten seeds may subsequently germinate.
The taller a Brazil nut tree is, _____.
1. the more valuable it is as a source of lumber
2. the less useful it is to harpy eagles
3. the greater its photosynthetic rate relative to neighboring plants
A) 1 only
B) 1 and 2
C) 1 and 3
D) 2 and 3
High levels of citric acid inhibit the enzyme phosphofructokinase, a key enzyme in
glycolysis. Citric acid binds to the enzyme at a different location from the active site.
This is an example of _____.
A) competitive inhibition
B) allosteric regulation
C) the specificity of enzymes for their substrates
D) positive feedback regulation
Carbon dioxide (CO2) is readily soluble in water, according to the equation CO2 + H2O
↔ H2CO3. Carbonic acid (H2CO3) is a weak acid. If CO2 is bubbled into a beaker
containing pure, freshly distilled water, which of the following graphs correctly
describes the results?
A)
B)
C)
D)
Examine the digestive system structures in the figure above. Bacteria that produce
vitamins are found in the greatest concentration in location _____.
A) 3
B) 4
C) 5
D) 8
A hydrocarbon skeleton is covalently bonded to an amino group at one end and a
carboxyl group at the other end. When placed in water this molecule would function
_____.
A) only as an acid because of the carboxyl group
B) only as a base because of the amino group
C) as an acid and a base
D) as neither an acid nor a base
Concerning growth in genome size over evolutionary time, which of these is LEAST
associated with the others?
A) orthologous genes
B) gene duplications
C) paralogous genes
D) gene families
What kinds of molecules pass through a cell membrane most easily?
A) large and hydrophobic
B) small and hydrophobic
C) large polar
D) ionic
The structure diagrammed in the figure is the _____.
A) neuromast
B) statocyst
C) ommatidium
D) olfactory bulb
You need to write down information about a molecule, but need to indicate only the
type and number of atoms it contains. Which representation would work best?
A) molecular formula
B) structural formula
C) ball-and-stick model
D) space-filling model
According to the theory of sea-floor spreading, oceanic islands, such as the Hawaiian
Islands depicted in the figure above, form as oceanic crustal plates move over a
stationary "hot spot" in the mantle. Currently, the big island of Hawaii is thought to be
over a hot spot, which is why it is the only one of the seven large islands that has active
volcanoes. What should be true of the island of Hawaii?
1. Scientists in search of ongoing speciation events are more likely to find them here
than on the other six large islands.
2. Its species should be more closely related to those of nearer islands than to those of
farther islands.
3. It should have a rich fossil record of terrestrial organisms.
4. It should have species that are not found anywhere else on Earth.
5. On average, it should have fewer species per unit surface area than the other six
islands.
A) 1, 2, and 3
B) 1, 2, and 5
C) 1, 2, 3, and 4
D) 1, 2, 4, and 5
In some circumstances, grasses benefit from being grazed. Which of the following
terms would best describe such a plant-herbivore interaction?
A) mutualism
B) commensalism
C) parasitism
D) predation
In the nematode C. elegans, ced-9 prevents apoptosis in a normal cell in which of the
following ways?
A) It prevents the caspase activity of ced-3 and ced-4.
B) Ced-9 remains inactive until it is signaled by ced-3 and other caspases.
C) Ced-9 cleaves to produce ced-3 and ced-4.
D) Ced-9 prevents blebbing by its action on the cell membrane.
African lungfish, which are often found in small, stagnant pools of fresh water, produce
urea as a nitrogenous waste. What is the advantage of this adaptation?
A) Urea takes less energy to synthesize than ammonia.
B) Small, stagnant pools do not provide enough water to dilute the toxic ammonia.
C) The highly toxic urea makes the pool uninhabitable to potential competitors.
D) Urea makes lungfish tissue hypoosmotic to the pool.
Which category in the figure above makes available the highest productivity per square
meter?
A) tropical wet forest
B) open ocean
C) algal beds and reefs
D) wetlands
Which of the following is a protein maintained at steady levels throughout the cell cycle
that requires cyclin to become catalytically active?
A) PDGF
B) MPF
C) cyclin
D) Cdk
Which molecule shown above contains a carboxyl group?
A) A
B) B
C) C
D) D
Hutchinson-Gilford progeria is an exceedingly rare human genetic disorder in which
there is very early senility and death, usually from coronary artery disease, at an
average age of 13 years. Patients, who look very old even as children, do not live to
reproduce. Which of the following represents the most likely assumption?
A) The disease is autosomal dominant.
B) The disorder will increase in frequency in successive generations within a family.
C) The disorder may be due to mutation in a single protein-coding gene.
D) Each patient will have had at least one affected grandparent or parent.
