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Which of the following statements about the cytoskeleton is true?
A) The cytoskeleton of eukaryotes is a static structure most resembling scaffolding used
at construction sites.
B) Although microtubules are common within a cell, actin filaments are rarely found
outside of the nucleus.
C) Movement of cilia and flagella is the result of motor proteins causing microtubules
to move relative to each other.
D) Chemicals that block the assembly of the cytoskeleton would have little effect on a
cell's response to external stimuli.
Which of the following is the correct sequence that describes the excitation and
contraction of a skeletal muscle fiber?
1. Tropomyosin shifts and unblocks the cross-bridge binding sites.
2. Calcium is released and binds to the troponin complex.
3. Transverse tubules depolarize the sarcoplasmic reticulum.
4. The thin filaments are ratcheted across the thick filaments by the heads of the myosin
molecules using energy from ATP.
5. An action potential in a motor neuron causes the axon to release acetylcholine, which
depolarizes the muscle cell membrane.
A) 1 → 2 → 3 → 4 → 5
B) 2 → 1 → 3 → 5 → 4
C) 2 → 3 → 4 → 1 → 5
D) 5 → 3 → 2 → 1 → 4
Our understanding of mental illness has been most advanced by discoveries involving
the _____.
A) degree of convolutions in the brain's surface
B) sequence of developmental specialization
C) chemicals involved in brain communications
D) nature of the blood-brain barrier
Because the foods eaten by animals are often composed largely of macromolecules,
animals need to have mechanisms for _____.
A) dehydration synthesis
B) enzymatic hydrolysis
C) regurgitation
D) demineralization
Based on their effects, which pair below would NOT be expected to be active at the
same time and place?
A) prostaglandin and nitric oxide
B) endocrine and exocrine glands
C) hormones and target cells
D) neurosecretory cells and neurotransmitters
The mechanism of cell crawling in protist species is not well defined. Pseudopodia
extension involves interactions between actin and myosin (the same molecules that are
involved in vertebrate muscle contraction). However, prior to the study described
below, no one had provided convincing data that actin and myosin were actually
involved in cell crawling in protists. Anatomical studies had identified the cytoskeletal
protein actin just below the surface of the cell membrane in several species of protist,
but physiological studies had failed to show a functional link between actin, myosin,
and cell crawling.
In a study by N. Poulsen et al. (Diatom gliding is the result of an actin-myosin motility
system, Cell Motility and the Cytoskeleton 44 (1999):23-22), researchers tested whether
motility in a particular species of diatom involves interactions between actin and
myosin.
Refer to the study by Poulsen et al. and the figure above. Cultures of a species of
diatom were treated with BDM, a reversible inhibitor of myosin function. Which of the
following predictions is consistent with the hypothesis that an actin-myosin interaction
is necessary for motility?
A) BDM will significantly decrease motility of the cells in culture.
B) BDM will not significantly alter motility of the cells in culture.
C) BDM will significantly increase motility of the cells in culture.
An animal cell lacking oligosaccharides on the external surface of its plasma membrane
would likely be impaired in which function?
A) transporting ions against an electrochemical gradient
B) cell-cell recognition
C) attaching the plasma membrane to the cytoskeleton
D) establishing a diffusion barrier to charged molecules
What is the maximum number of covalent bonds that an oxygen atom with atomic
number 8 can make with hydrogen?
A) 1
B) 2
C) 4
D) 6
One of the waste products that accumulates during cellular functions is carbon dioxide.
It is removed via the respiratory system. What is another waste product that
accumulates during normal physiological functions in vertebrates?
I) ammonia
II) uric acid
III) urea
A) only I and III
B) only II and III
C) only I and II
D) I, II, and III
Arrange the following in the correct sequence, from earliest to most recent, in which
these plant traits originated.
1. sporophyte dominance, gametophyte independence
2. sporophyte dominance, gametophyte dependence
3. gametophyte dominance, sporophyte dependence
A) 1 →? 2 → 3
B) 2 → 1 → 3
C) 3 → 2 → 1
D) 3 → 1 → 2
If the figure above shows the dances of bees in a hive at twelve noon on March 21 in
the northern hemisphere, which dance is communicating that the food is to the south of
the hive?
A) dance A
B) dance B
C) dance C
D) It is not possible to tell if any of the dances indicate the food is to the south of the
hive.
Water flows into the source end of a sieve tube because _____.
A) sucrose has been actively transported into the sieve tube, making it hypertonic
B) water pressure outside the sieve tube forces in water
C) the companion cell of a sieve tube actively pumps in water
D) sucrose has been transported out of the sieve tube by active transport
When a mosquito infected with Plasmodium first bites a human, the Plasmodium
_____.
A) gametes fuse, forming an oocyst
B) cells infect the human liver cells
C) cells cause lysing of the human red blood cells
D) oocyst undergoes meiosis
During fertilization, the acrosomal contents _____.
A) block polyspermy
B) help propel more sperm toward the egg
C) digest the protective jelly coat on the surface of the egg
D) trigger the completion of meiosis by the sperm
A microarray is a tool used in genetic research to determine the mRNAs being produced
in a particular tissue, and their relative level of expression. Known genes can therefore
be assayed for their expression in different situations. One use of the technology is in
cancer diagnosis and treatment. If a known gene functions as a tumor suppressor,
predict which of the following pieces of evidence would be most useful in diagnosis of
a cancer due to a mutation in this tumor-suppressor gene.
A) The tissue sample shows a high level of gene expression relative to a control
(noncancerous) sample.
B) The tissue sample responds to treatment with a mitosis-promoting compound.
C) The mRNAs for the targeted tumor suppressor sequence are not being produced.
D) The mRNAs for cyclins and kinases show unusually high levels of expression.
Adult male humans generally have deeper voices than do adult female humans, which
is the direct result of higher levels of testosterone causing growth of the larynx. If the
fossil records of apes and humans alike show a trend toward decreasing larynx size in
adult females and increasing larynx size in adult males, then _____.
A) sexual dimorphism was evolving over time in these species
B) intrasexual selection seems to have occurred in both species
C) stabilizing selection was occurring in these species concerning larynx size
D) selection was acting more directly upon genotype than upon phenotype
A fruit fly, internally infected by a potentially pathogenic fungus, is protected by its
_____.
A) immunoglobulins
B) antibodies
C) antimicrobial peptides
D) B cells
Dizziness is a perceived sensation that can occur when _____.
A) the hair cells in the cochlea move more than their normal limits
B) moving fluid in the semicircular canals encounters a stationary cupula
C) rods and cones provide information that does not correspond with information
received by cochlear hair cells
D) the basilar membrane makes physical contact with the tectorial membrane
Of the following types of molecules, which can function as both neurotransmitters and
hormones?
A) glucocorticoids
B) second messengers
C) catecholamines
D) adipocytes
Chloramphenicol is an antibiotic that targets prokaryotic (70S) ribosomes, but not
eukaryotic (80S) ribosomes. Which of these questions stems from this observation, plus
an understanding of eukaryotic origins?
A) Can chloramphenicol also be used to control human diseases that are caused by
archaeans?
B) Can chloramphenicol pass through the capsules possessed by many cyanobacteria?
C) If chloramphenicol inhibits prokaryotic ribosomes, should it not also inhibit
mitochondrial ribosomes?
D) Why aren't prokaryotic ribosomes identical to eukaryotic ribosomes?
Why do RNA viruses appear to have higher rates of mutation?
A) RNA nucleotides are more unstable than DNA nucleotides.
B) Replication of their genomes does not involve proofreading.
C) RNA viruses can incorporate a variety of nonstandard bases.
D) RNA viruses are more sensitive to mutagens.
DNA contains the template needed to copy itself, but it has no catalytic activity in cells.
What catalyzes the formation of phosphodiester bonds between adjacent nucleotides in
the DNA polymer being formed?
A) ribozymes
B) DNA polymerase
C) ATP
D) deoxyribonucleotide triphosphates
The arrangement of organs and tissues in their characteristic places in 3-D space defines
_____.
A) pattern formation
B) differentiation
C) determination
D) organogenesis
Short-term and long-term memory are related but have important differences.
Short-term memory _____.
A) involves temporary links formed in the cerebral cortex while long-term memory
involves permanent connections within the hippocampus
B) and long-term memory store information in the cerebellum but use different
neurotransmitters
C) is essential for acquiring and retaining long-term memories
D) is essential for acquiring new long-term memories but not for maintaining them
What was the most significant conclusion that Gregor Mendel drew from his
experiments with pea plants?
A) There is considerable genetic variation in garden peas.
B) Traits are inherited in discrete units and are not the results of "blending."
C) Recessive genes occur more frequently in the F1 generation than do dominant ones.
D) Genes are composed of DNA.
I. II.
III. IV.
Which tree depicts the microsporidians as a sister group of the ascomycetes?
A) I
B) II
C) III
D) IV
The liver is involved in detoxification of many poisons and drugs. Which of the
following structures is primarily involved in this process and, therefore, abundant in
liver cells?
A) rough ER
B) smooth ER
C) Golgi apparatus
D) nuclear envelope
How do cells use the ATP cycle shown in the figure?
A) Cells use the cycle to recycle ADP and phosphate.
B) Cells use the cycle to recycle energy released by ATP hydrolysis.
C) Cells use the cycle to recycle ADP, phosphate, and the energy released by ATP
hydrolysis.
D) Cells use the cycle primarily to generate heat.
In plant roots, the Casparian strip _____.
A) aids in the uptake of nutrients
B) provides energy for the active transport of minerals into the stele from the cortex
C) ensures that all minerals are absorbed from the soil in equal amounts
D) ensures that all water and dissolved substances must pass through a cell membrane
before entering the stele
Recall that Clements's view of biological communities is that of a highly predictable
and interrelated structure, while Gleason's view of biological communities is that
individual species operate independently. If we set up many identical sterilized ponds in
the same area and allowed them to be colonized, what should we predict if we wished
to test Gleason's hypothesis?
A) Identical plankton communities will develop in all ponds.
B) Similar plankton communities will develop in all ponds.
C) Different plankton communities will develop in all ponds.
D) Limited plankton communities will develop in all ponds.
A sequence database such as GenBank could be used to do all of the following
EXCEPT
A) Compare cow and human insulin protein sequences.
B) Construct a tree to determine the evolutionary relationships between various bird
species.
C) Search for genes in a fruit fly that are similar to a human gene.
D) Compare patterns of gene expression in cancerous and non-cancerous cells.
One of the primary functions of RNA molecules is to _____.
A) transmit genetic information to offspring
B) function in the synthesis of proteins
C) make a copy of itself, thus ensuring genetic continuity
D) act as a pattern or blueprint to form DNA
Which branch of biology is concerned with the naming and classifying of organisms?
A) informatics
B) taxonomy
C) genomics
D) evolution
