During which phase of mitosis do the chromatids become chromosomes?
A) telophase
B) anaphase
C) prophase
D) metaphase
Chemical equilibrium is relatively rare in living cells. An example of a reaction at
chemical equilibrium in a cell would be _____.
A) one in which the free energy at equilibrium is higher than the energy content at any
point away from equilibrium
B) one in which the entropy change in the reaction is just balanced by an opposite
entropy change in the cell’s surroundings
C) an endergonic reaction in an active metabolic pathway where the energy for that
reaction is supplied only by heat from the environment
D) a chemical reaction in which both the reactants and products are not being produced
or used in any active metabolic pathway at that time in the cell
Trichoplax adhaerens (Tp) is the only living species in the phylum Placozoa.
Individuals are about 1 mm wide and only 27 μm high, are irregularly shaped, and
consist of a total of about 2000 cells, which are diploid (2n = 12). There are four types
of cells, none of which are nerve or muscle cells, and none of which have cell walls.
They move using cilia, and any “edge” can lead. Tp feeds on marine microbes, mostly
unicellular green algae, by crawling atop the algae and trapping it between its ventral
surface and the substrate. Enzymes are then secreted onto the algae, and the resulting
nutrients are absorbed. Tp sperm cells have never been observed, nor have embryos
past the 64-cell (blastula) stage.
Tp’s body symmetry seems to be most like that of _____.
A) most sponges
B) cnidarians
C) worms
D) tetrapods
Using the table above, how would you describe the population dynamics of L. vivipara?
A) The population is increasing.
B) The population is decreasing.
C) The population is stable.
D) The figure does not provide this information.
During most daily activities, the human respiration rate is most closely linked to the
blood levels of _____.
A) nitrogen
B) oxygen
C) carbon dioxide
D) carbon monoxide
DNA methylation and histone acetylation are examples of _____.
A) genetic mutation
B) chromosomal rearrangements
C) epigenetic phenomena
D) translocation
The activity of acetylcholine in a synapse is terminated by its_____.
A) diffusion across the presynaptic membrane
B) active transport across the postsynaptic membrane
C) diffusion across the postsynaptic membrane
D) degradation on the postsynaptic membrane
Sister chromatids separate from each other during _____.
A) meiosis I only
B) meiosis II only
C) mitosis and meiosis I
D) mitosis and meiosis II
The duplication of homeotic (Hox) genes has been significant in the evolution of
animals because it _____.
A) permitted the evolution of novel forms
B) caused the extinction of major groups
C) reduced morphological diversity into simpler forms of life
D) allowed animals to survive on significantly fewer calories
Arrange the following structures from largest to smallest, assuming that they belong to
two generations of the same angiosperm.
1. ovary
2. ovule
3. egg
4. carpel
5. embryo sac
A) 4, 5, 2, 1, 3
B) 5, 4, 3, 1, 2
C) 5, 1, 4, 2, 3
D) 4, 1, 2, 5, 3
Two populations of birds with somewhat different coloration live on opposite sides of a
peninsula. The habitat between the populations is not suitable for these birds. When
birds from the two populations are brought together, they produce young whose
appearance is intermediate between the two parents. These offspring will breed with
each other or with birds from either parent population, and all offspring of these
pairings appear intermediate to various degrees.
What keeps the two populations separate?
A) temporal reproductive isolation
B) lack of hybrid viability
C) behavioral reproductive isolation
D) habitat isolation
Ammonia is likely to be the primary nitrogenous waste in living conditions that include
_____.
A) lots of fresh water flowing across the gills of a fish
B) lots of seawater, such as a bird living in a marine environment
C) a terrestrial environment, such as that supporting crickets
D) a moist system of burrows, such as those of naked mole rats
The least amount of yolk would be found in the egg of a _____.
A) bird
B) frog
C) eutherian mammal
D) reptile
Garrod hypothesized that “inborn errors of metabolism” such as alkaptonuria occur
because _____.
A) metabolic enzymes require vitamin cofactors, and affected individuals have
significant nutritional deficiencies
B) enzymes are made of DNA, and affected individuals lack DNA polymerase
C) certain metabolic reactions are carried out by ribozymes, and affected individuals
lack key splicing factors
D) genes dictate the production of specific enzymes, and affected individuals have
genetic defects that cause them to lack certain enzymes
Scientists have tried raising endangered whooping cranes in captivity by using sandhill
cranes as foster parents. This strategy is no longer used because _____.
A) the fostered whooping cranes’ critical period was variable such that different chicks
imprinted on different “mothers”
B) sandhill crane parents rejected their fostered whooping crane chicks soon after
incubation
C) none of the fostered whooping cranes formed a mating pair-bond with another
whooping crane
D) sandhill crane parents did not properly incubate whooping crane eggs
Some plants have continually produced secondary defense compounds. Other plants are
induced to form secondary defense compounds when they are injured. Corn seedling
leaves that are chewed on by the caterpillars of a type of cutworm moth emit immediate
volatile chemicals (LOX products), and after six hours large amounts of terpenoid
compounds are released into the air. The terpenoids are released not only from the leaf
being chewed, but from all leaves of the plant. The terpenoid compounds attract a
parasitoid wasp female that lays her eggs on the caterpillar. When the wasp larvae
hatch, they eat and kill the moth caterpillar. (T.C.J. Turlings, J. H. Loughrin, P. J.
McCall, U. S. R. Rose, W. J. Lewis, and J. H. Tumlinson. 1995. How
caterpillar-damaged plants protect themselves by attracting parasitic wasps.
Proceedings of the National Academy of Sciences 92:4169-74.)
Refer to the paragraph on how caterpillar-damaged plants protect themselves by
attracting parasitic wasps. What can you conclude based only on the information in the
preceding paragraph?
A) The attracting terpenoid compounds are always present in the corn seedling.
B) Physical injury by the caterpillar mouthparts results in the immediate release of
terpenoids.
C) Chemical signals from the caterpillar saliva attract the parasitic wasp.
D) The parasitoid wasp is attracted by compounds produced by an injured corn plant.
Glucose-6-phosphate dehydrogenase deficiency (G6PD) is inherited as a recessive
allele of an X-linked gene in humans. A woman whose father suffered from G6PD
marries a normal man.
(a) What proportion of their sons is expected to be G6PD?
(b) If the husband was not normal but was G6PD deficient, would you change your
answer in part (a)?
A) (a) 100%; (b) no
B) (a) 1/2; (b) yes
C) (a) 1/2; (b) no
D) (a) zero; (b) no
If a prairie dog had the opportunity to perform an altruistic act (that is, give an alarm
call) to help its relatives, which combination of the following relatives would the prairie
dog be most likely to help (base your answer solely on the genetic relationships)?
A) two nieces, two cousins, and one half-brother
B) two half-sisters and two nieces
C) one son, one niece, and one half-sister
D) The prairie dog would be equally likely to act altruistically to each of the
combinations described.
Which of the following statements about the 5′ end of a polynucleotide strand of RNA
is correct?
A) The end has a hydroxyl group attached to the number 5 carbon of ribose.
B) The end has a phosphate group attached to the number 5 carbon of ribose.
C) The end has phosphate attached to the number 5 carbon of the nitrogenous base.
D) The end has a carboxyl group attached to the number 5 carbon of ribose.
Which organelle or structure is absent in plant cells?
A) mitochondria
B) microtubules
C) centrosomes
D) peroxisomes
Which statement is most consistent with the hypothesis that the Cambrian explosion
was caused by the rise of predator-prey relationships? The fossil record reveals an
increased incidence of _____.
A) worm burrows
B) larger animals
C) organic material
D) hard parts
You have found a new prokaryote. What line of evidence would support your
hypothesis that the organism is a cyanobacterium?
A) It is able to form colonies and produce oxygen.
B) It is an endosymbiont.
C) It forms chains called mycelia.
D) It lacks cell walls.
Data were collected from the heterocysts of a nitrogen-fixing cyanobacterium
inhabiting equatorial ponds. Study the following graph and choose the most likely
explanation for the shape of the curve.
A) Enough oxygen (O2) enters heterocysts during hours of peak photosynthesis to have
a somewhat-inhibitory effect on nitrogen fixation.
B) Atmospheric nitrogen (N2) levels increase at night because plants are no longer
metabolizing this gas, so they are not absorbing this gas through their stomata.
C) Heterocyst walls become less permeable to nitrogen (N2) influx during darkness.
D) The amount of fixed nitrogen that is dissolved in the pond water in which the
cyanobacteria are growing peaks at the close of the photosynthetic day (1800 hours).
Suppose that the cells of seed plants, like the skin cells of humans, produce a pigment
upon increased exposure to ultraviolet radiation. Rank the following cells, from greatest
to least, in terms of the likelihood of producing this pigment.
1. cells of sporangium
2. cells in the interior of a subterranean root
3. epidermal cells of sporophyte megaphylls
4. cells of a gametophyte
A) 3, 4, 1, 2
B) 3, 4, 2, 1
C) 3, 1, 4, 2
D) 3, 2, 1, 4
Action potentials move along axons _____.
A) more slowly in axons of large than in small diameter
B) by activating the sodium-potassium “pump” at each point along the axonal
membrane
C) more rapidly in myelinated than in non-myelinated axons
D) by reversing the concentration gradients for sodium and potassium ions
Testosterone is an example of a chemical signal that affects the very cells that
synthesize it, the neighboring cells in the testis, along with distant cells outside the
gonads. Thus, testosterone is an example of _____.
I) an autocrine signal
II) a paracrine signal
III) an endocrine signal
A) only I and II
B) only II and III
C) only I and III
D) I, II, and III
Phenylketonuria is an inherited disease caused by a recessive autosomal allele. If a
woman and her husband are both carriers, what is the probability that their first child
will be a phenotypically normal girl?
A) 1/4
B) 1/16
C) 3/16
D) 3/8
Which clade does NOT include humans?
A) lobe-fins
B) diapsids
C) craniates
D) osteichthyans
A couple has a child with Down syndrome. The mother is 39 years old at the time of
delivery. Which of the following is the most probable cause of the child’s condition?
A) The woman inherited this tendency from her parents.
B) The mother had a chromosomal duplication.
C) One member of the couple underwent nondisjunction in somatic cell production.
D) The mother most likely underwent nondisjunction during gamete production.
Which of the following ions is most likely to cross the plasma membrane of a resting
neuron?
A) K+
B) Na+
C) Ca2+
D) Cl–
Density-dependent inhibition is explained by which of the following?
A) As cells become more numerous, they begin to squeeze against each other,
restricting their size and ability to produce control factors.
B) As cells become more numerous, the cell surface proteins of one cell contact the
adjoining cells and they stop dividing.
C) As cells become more numerous, the protein kinases they produce begin to compete
with each other, such that the proteins produced by one cell essentially cancel those
produced by its neighbor.
D) As cells become more numerous, the level of waste products increases, eventually
slowing down metabolism.
If 14C -labeled uracil is added to the growth medium of cells, what macromolecules will
be labeled?
A) DNA
B) RNA
C) both DNA and RNA
D) proteins
How many molecules of water are used to completely hydrolyze a polymer that is 11
monomers long?
A) 12
B) 11
C) 10
D) 9
When homologous chromosomes cross over, what occurs?
A) Two chromatids get tangled, resulting in one re-sequencing its DNA.
B) Two sister chromatids exchange identical pieces of DNA.
C) Corresponding segments of non-sister chromatids are exchanged.
D) Maternal alleles are “corrected” to be like paternal alleles and vice versa.