When adult amphibian skin harbors populations of the bacterium, Janthinobacterium
lividum (Jl), chytrid infection seems to be inhibited. Which of the following represents
the best experimental design to test whether this inhibition is real?
A) Inoculate uninfected amphibians with Jl, and determine whether the amphibians
continue to remain uninfected by chytrids.
B) Inoculate infected amphibians with Jl, and determine whether the amphibians
recover from infection by chytrids.
C) Take infected amphibians and assign them to two populations. Leave one population
alone; inoculate the other with Jl. Measure the rate at which infection proceeds in both
populations.
D) Take infected amphibians and assign them to two populations. Inoculate one
population with a high dose of Jl; inoculate the other with a low dose of Jl. Measure the
survival frequency in both populations.
Which of the following pairs of protists and their characteristics is mismatched?
A) apicomplexans internal parasites
B) euglenozoans unicellular flagellates
C) ciliates red tide organisms
D) entamoebas ingestive heterotrophs
Phenylketonuria (PKU) is a recessive human disorder in which an individual cannot
appropriately metabolize the amino acid phenylalanine. This amino acid is not naturally
produced by humans. Therefore, the most efficient and effective treatment is which of
the following?
A) Feed them the substrate that can be metabolized into this amino acid.
B) Regulate the diet of the affected persons to severely limit the uptake of the amino
acid.
C) Feed the patients the missing enzymes in a regular cycle, such as twice per week.
D) Feed the patients an excess of the missing product.
The cycads, a mostly tropical phylum of gymnosperms, evolved about 300 million
years ago and were dominant forms during the Age of the Dinosaurs. Though their
sperm are flagellated, their ovules are pollinated by beetles. These beetles get nutrition
(they eat pollen) and shelter from the microsporophylls. Upon visiting
megasporophylls, the beetles transfer pollen to the exposed ovules. In cycads, pollen
cones and seed cones are borne on different plants. Cycads synthesize neurotoxins,
especially in the seeds, that are effective against most animals, including humans.
If the beetles survive by consuming cycad pollen, then whether the beetles should be
considered mutualists with, or parasites of, the cycads depends upon the ____.
A) extent to which their overall activities affect cycad reproduction
B) extent to which the beetles are affected by the neurotoxins
C) extent to which the beetles damage the cycad flowers
D) distance the beetles must travel between cycad microsporophylls and cycad
megasporophylls
In Drosophila melanogaster, vestigial wings are caused by a recessive allele of a gene
that is linked to a gene with a recessive allele that causes black body color. Morgan
crossed black-bodied, normal-winged females and gray-bodied, vestigial-winged males.
The F1 were all gray bodied, normal winged. The F1 females were crossed to
homozygous recessive males to produce testcross progeny. Morgan calculated the map
distance to be 17 map units. Which of the following is correct about the testcross
progeny?
A) black-bodied, normal-winged flies = 17% of the total
B) black-bodied, normal-winged flies PLUS gray-bodied, vestigial-winged flies = 17%
of the total
C) gray-bodied, normal-winged flies PLUS black-bodied, vestigial-winged flies = 17%
of the total
D) black-bodied, vestigial-winged flies = 17% of the total
Several tomato plants are growing in a small garden plot. If soil water potential were to
drop significantly on a hot, summer afternoon, which of the following would most
likely occur?
A) Size of stomatal openings would decrease.
B) Transpiration would increase.
C) The leaves would become more turgid.
D) The uptake of carbon dioxide would be enhanced.
In a tide pool, fifteen species of invertebrates were reduced to eight after one species
was removed. The species removed was likely a(n) _____.
A) pathogen
B) keystone species
C) herbivore
D) resource partitioner
If a cell is able to synthesize 30 ATP molecules for each molecule of glucose completely
oxidized to carbon dioxide and water, approximately how many ATP molecules can the
cell synthesize for each molecule of pyruvate oxidized to carbon dioxide and water?
A) 0
B) 12
C) 14
D) 26
A human red blood cell in an artery of the left arm is on its way to deliver oxygen to a
cell in the thumb. To travel from the artery to the thumb and then back to the left
ventricle, this red blood cell must pass through _____.
A) one capillary bed
B) two capillary beds
C) three capillary beds
D) four capillary beds
Comparisons of DNA sequences within the human species have revealed many
variations. Which of the following variations involves duplication of relatively long
stretches of chromosomes, often including the duplication of protein-coding genes?
A) CNVs
B) SNPs
C) STRs
D) Transposable elements
Transcription of structural genes in an inducible operon _____.
A) occurs continuously in the cell
B) starts when the pathway’s substrate is present
C) starts when the pathway’s product is present
D) stops when the pathway’s product is present
How does termination of translation take place?
A) The end of the mRNA molecule is reached.
B) A stop codon is reached.
C) The cap is reached.
D) The poly-A tail is reached.
In onions (Allium), cells of the sporophyte have 16 chromosomes within each nucleus.
Match the number of chromosomes present in each of the following onion tissues.
How many chromosomes should be in a megasporangium nucleus?
A) 8
B) 16
C) 24
D) 32
Which molecule shown above contains an amino functional group, but is NOT an
amino acid?
A) A
B) B
C) C
D) D
Which enzyme was used to produce the molecule in the figure above?
A) ligase
B) a restriction enzyme (endonuclease)
C) RNA polymerase
D) DNA polymerase
When the mammalian brain compares the actual temperature of the body to the
preferred temperature of the body, which general component is being used?
A) sensor
B) effector
C) integrator
Fossils of Thrinaxodon, a species that lived during the Triassic period, have been found
in both South Africa and Antarctica. Thrinaxodon had a reptile-like skeleton and laid
eggs, but small depressions on the front of its skull suggest it had whiskers and,
therefore, fur. Thrinaxodon may have been warm-blooded. The fossils of Thrinaxodon
are consistent with the hypothesis that _____.
A) fossils found in a given area look like the modern species in that same area
B) the environment where it lived was very warm
C) mammals evolved from a reptilian ancestor
D) Antarctica and South Africa separated after Thrinaxodon went extinct
Which of the following provides an example of epistasis?
A) Recessive genotypes for each of two genes (aabb) results in an albino corn snake.
B) In rabbits and many other mammals, one genotype (ee) prevents any fur color from
developing.
C) In Drosophila (fruit flies), white eyes can be due to an X-linked gene or to a
combination of other genes.
D) In cacti, there are several genes for the type of spines.
A part of an mRNA molecule with the following sequence is being read by a ribosome:
CCG-ACG (mRNA). The following charged transfer RNA molecules (with their
anticodons shown in the to direction) are available. Two of them can correctly
match the mRNA so that a dipeptide can form.
The anticodon loop of the first tRNA that will complement this mRNA is
A) GGC
B) GGC
C) UGC
D) UGC
If two species are close competitors, and one species is experimentally removed from
the community, the remaining species would be expected to _____.
A) change its fundamental niche
B) decline in abundance
C) become the target of specialized parasites
D) expand its realized niche
Fossils of the earliest tetrapods should _____.
A) show evidence of internal fertilization
B) show evidence of having produced shelled eggs
C) indicate limited adaptation to life on land
D) feature the earliest indications of the appearance of jaws
On the diagram of the nitrogen cycle, which number represents nitrite (NO2)?
A) 1
B) 2
C) 3
D) 4
Arrange the following in order from largest to smallest, assuming that they all come
from the same fungus.
1. basidiocarp
2. basidium
3. basidiospore
4. mycelium
5. gill
A) 4 →? 5 → 1→ 2 → 3
B) 5 → 1 → 4 → 2 → 3
C) 5 → 1 → 3 → 2 → 4
D) 4 → 1 → 5 → 2 → 3
Why is ATP an important molecule in metabolism?
A) Its hydrolysis provides an input of free energy for exergonic reactions.
B) It provides energy coupling between exergonic and endergonic reactions.
C) Its terminal phosphate group contains a strong covalent bond that, when hydrolyzed,
releases free energy.
D) Its terminal phosphate bond has higher energy than the other two phosphate bonds.
If a fossil is encased in a stratum of sedimentary rock without any strata of volcanic
rock (for example, lava or ash) nearby, then it should be _____.
A) easy to determine the absolute age of the fossil, because the radioisotopes in the
sediments will not have been “reset” by the heat of the igneous rocks
B) easy to determine the absolute age of the fossil, because the igneous rocks will not
have physically obstructed the deposition of sediment of a single age next to the fossil
C) difficult to determine the absolute age of the fossil, because the “marker fossils”
common to igneous rock will be absent
D) difficult to determine the absolute age of the fossil, because radiometric dating of
sedimentary rock is less accurate than that of igneous rock
Pseudogenes are _____.
A) composed of RNA, rather than DNA
B) the same things as introns
C) unrelated genes that code for the same gene product
D) nonfunctional vestigial genes
Fruit ripening represents an example of positive feedback. Which one of the following
statements accurately justifies why the process of fruit ripening involves positive
feedback?
A) Once seeds have reached maturity, chemical signals increase enzymatic activity in
fruit to convert sugars into starches, thicken pulp, and maintain color in the fruit.
B) Once seeds have reached maturity, chemical signals block enzymatic steps that
normally convert sugars into starches and sugars accumulate from photosynthetic
activity within the fruit.
C) Chemical signals initiate a process that triggers enzymatic activity, which involves
converting starches into sugars, softening of pulp, and color change of fruit.
D) Chemical signals shut down enzymatic activity within the fruit, which results in
breakdown of starches into sugars, softening of pulp, and color change of fruit.
Diatoms are encased in petri-platelike cases (valves) made of translucent hydrated silica
whose thickness can be varied. The material used to store excess calories can also be
varied. At certain times, diatoms store excess calories in the form of the liquid
polysaccharide, laminarin, and at other times as oil. The following are data concerning
the density (specific gravity) of various components of diatoms, and of their
environment.
Specific Gravities of Materials Relevant to Diatoms
Water’s density and, consequently, its buoyancy decrease at warmer temperatures.
Considering the impact of temperature, and the table above, in which environment
should diatoms sinking be slowest?
A) cold fresh water
B) warm fresh water
C) cold seawater
D) warm seawater
Which of the following experiments best addresses the hypothesis that moths stop
flying in response to high-intensity bat sounds?
A) Isolate and characterize the neurons that control flight muscle.
B) Play prerecorded high-intensity bat sounds to flying moths.
C) Observe responses of moths to bats in nature.
D) Put bats and moths in an enclosure and make detailed observations of predator-prey
interactions.
Which of the following is a consequence of biological magnification
(biomagnification)?
A) Toxic chemicals in the environment pose greater risk to top-level predators than to
primary consumers.
B) Populations of top-level predators are generally smaller than populations of primary
consumers.
C) Only a small portion of the energy captured by producers is transferred to
consumers.
D) The amount of biomass in the producer level of an ecosystem decreases if the
producer turnover time increases.