After looking at the figure above, what can be said about productivity in this
ecosystem?
A) Nothing can be said based on this information.
B) Between 80% and 90% of the energy is lost between most trophic levels.
C) Between 10% and 20% of the energy is lost between most trophic levels.
D) Productivity increases with each trophic level.
Use the following figure and information to answer the question(s) below.
Fishes that have swim bladders can regulate their density and, thus, their buoyancy.
There are two types of swim bladder: physostomous and physoclistous. The ancestral
version is the physostomous version, in which the swim bladder is connected to the
esophagus via a short tube (see the figure above). The fish fills this version by
swimming to the surface, taking gulps of air, and directing them into the swim bladder.
Air is removed from this version by “belching.” The physoclistous version is more
derived, and has lost its connection to the esophagus. Instead, gas enters and leaves the
swim bladder via special circulatory mechanisms within the wall of the swim bladder.
If a ray-finned fish is to both hover (remain stationary) in the water column and
ventilate its gills effectively, then what other structure besides its swim bladder will it
use?
A) its pectoral fins
B) its lateral line system
C) its caudal (tail) fin
D) its opercula
Which of the following is one of the technical reasons why gene therapy is
problematic?
A) Most cells with an engineered gene do not produce gene product.
B) Cells with transferred genes are unlikely to replicate.
C) Transferred genes may not have appropriately controlled activity.
D) mRNA from transferred genes cannot be translated.
The generative cell of male angiosperm gametophytes is haploid. This cell divides to
produce two haploid sperm cells. What type of cell division does the generative cell
undergo to produce these sperm cells?
A) binary fission
B) mitosis
C) meiosis
D) meiosis without subsequent cytokinesis
The regulation of body temperature derives from the activity of the _____.
A) cerebrum
B) cerebellum
C) thalamus
D) hypothalamus
New biosensors, applied like a temporary tattoo to the skin, can alert serious athletes
that they are about to “hit the wall” and find it difficult to continue exercising. These
biosensors monitor lactate, a form of lactic acid, released in sweat during strenuous
exercise.
Which of the statements below is the best explanation of why athletes would need to
monitor lactate levels?
A) During aerobic respiration, muscle cells cannot produce enough lactate to fuel
muscle cell contractions and muscles begin to cramp, thus athletic performance suffers.
B) During anaerobic respiration, lactate levels increase when muscles cells need more
energy, however muscles cells eventually fatigue, thus athletes should modify their
activities to increase aerobic respiration.
C) During aerobic respiration, muscles cells produce too much lactate which causes a
rise in the pH of the muscle cells, thus athletes must consume increased amounts of
sports drinks, high in electrolytes, to buffer the pH.
D) During anaerobic respiration, muscle cells receive too little oxygen and begin to
convert lactate to pyruvate (pyruvic acid), thus athletes experience cramping and
fatigue.
Following glycolysis and the citric acid cycle, but before the electron transport chain
and oxidative phosphorylation, the carbon skeleton of glucose has been broken down to
CO2 with some net gain of ATP. Most of the energy from the original glucose molecule
at that point in the process, however, is in the form of _____.
A) acetyl-CoA
B) glucose
C) pyruvate
D) NADH
Synthesis of which of the following compounds in a mature leaf would be least
impacted by a temporary soil nitrogen deficiency?
A) DNA
B) RNA
C) amino acids
D) cellulose
If you think of the earthworm body plan as a drinking straw within a pipe, where would
you expect to find most of the tissues that developed from endoderm?
A) lining the straw
B) lining the space between the pipe and the straw
C) forming the outside of the pipe
D) forming the outside of the straw
What does it mean to say that a signal is transduced?
A) The signal enters the cell directly and binds to a receptor inside.
B) The physical form of the signal changes from one form to another.
C) The signal is amplified, such than even a single molecule evokes a large response.
D) The signal triggers a sequence of phosphorylation events inside the cell.
If all prokaryotes on Earth suddenly vanished, which of the following would be the
most likely and most direct result?
A) Human populations would thrive in the absence of disease.
B) Bacteriophage numbers would dramatically increase.
C) The recycling of nutrients would be greatly reduced, at least initially.
D) There would be no more pathogens on Earth.
One of the buffers that contribute to pH stability in human blood is carbonic acid
(H2CO3). Carbonic acid is a weak acid that, when placed in an aqueous solution,
dissociates into a bicarbonate ion (HCO3-) and a hydrogen ion (H+), as noted below.
If the pH of blood drops, one would expect _____.
A) a decrease in the concentration of H2CO3 and an increase in the concentration of
HCO3–
B) the concentration of bicarbonate ions (HCO3-) to increase
C) the HCO3– to act as a base and remove excess H+ by the formation of H2CO3
D) the HCO3– to act as an acid and remove excess H+ by the formation of H2CO3
Which of the following is characteristic of a steroid hormone action?
A) protein phosphorylation
B) cell-surface receptor binding
C) internal receptor binding
D) second messenger activation
Carbon dioxide levels in the blood and cerebrospinal fluid affect pH. This enables the
organism to sense a disturbance in gas levels as _____.
A) the brain directly measures and monitors oxygen levels and causes breathing
changes accordingly
B) the medulla oblongata, which is in contact with cerebrospinal fluid, monitors pH and
uses this measure to control breathing
C) the brain alters the pH of the cerebrospinal fluid to force the animal to retain more or
less carbon dioxide
D) stretch receptors in the lungs cause the medulla oblongata to speed up or slow
breathing
The molecule shown the accompanying figure is a _____.
A) fatty acid
B) steroid
C) protein
D) phospholipid
Use the following information to answer the question(s) below.
Giardia intestinalis can cause disease in several different mammalian species, including
humans. Giardia organisms (G. intestinalis) that infect humans are similar
morphologically to those that infect other mammals; thus they have been considered a
single species. However, G. intestinalis has been divided into different subgroups based
on their host and a few other characteristics.
In 1999, a DNA sequence comparison study tested the hypothesis that these subgroups
actually constitute different species. The following phylogenetic tree was constructed
from the sequence comparison of rRNA from several subgroups of G. intestinalis and a
few other morphologically distinct species of Giardia. The researchers concluded that
the subgroups of Giardia are sufficiently different from one another genetically that
they could be considered different species. (T. Monis et al. 1999. Molecular systematics
of the parasitic protozoan Giardia intestinalis. Mol. Biol. Evol. 16[9]:1135-44.)
According to the phylogenetic tree in the figure above, G. intestinalis constitutes a
_____ group.
A) paraphyletic
B) monophyletic
C) polyphyletic
Which of the following is true of enzymes?
A) Enzyme function is increased if the 3- D structure or conformation of an enzyme is
altered.
B) Enzyme function is independent of physical and chemical environmental factors
such as pH and temperature.
C) Enzymes increase the rate of chemical reaction by lowering activation energy
barriers.
D) Enzymes increase the rate of chemical reaction by providing activation energy to the
substrate.
During an auditory transduction, ion flow varies across the _____.
A) tectorial membrane
B) round-window membrane
C) hair cell membrane
D) basilar membrane
Use the following information when to answer the question(s) below.
Many terrestrial arthropods exchange gases with their environments by using tracheae,
tubes that lead from openings (called spiracles) in the animal’s exoskeleton or cuticle
directly to the animal’s tissues. Some arthropods can control whether their spiracles are
opened or closed; opening the spiracles allows the carbon dioxide produced in the
tissues to travel down the tracheae and be released outside the animal. Klok et al.
measured the carbon dioxide emitted over time (represented by ) by several
species of centipedes. The figure below presents graphs of their results for two species,
Cormocephalus morsitans and Scutigerina weberi. (C. J. Klok, R. D. Mercer, and S. L.
Chown. 2002. Discontinuous gas-exchange in centipedes and its convergent evolution
in tracheated arthropods. Journal of Experimental Biology 205:1019-29.) Copyright
2002 The Company of Biologists and the Journal of Experimental Biology.
Look at the graph for Cormocephalus morsitans in the figure above. What is the best
interpretation of these results?
A) The centipede had its spiracles open the entire time.
B) The centipede had its spiracles closed the entire time.
C) The centipede had its spiracles open when carbon dioxide (CO2) emission peaked
and closed when CO2 emission was low.
D) The centipede had its spiracles closed when carbon dioxide (CO2) emission peaked
and open when CO2 emission was low.
The questions below refer to the following table, which compares the % sequence
homology of four different parts (two introns and two exons) of a gene that is found in
five different eukaryotic species. Each part is numbered to indicate its distance from the
promoter (for example, Intron I is the one closest to the promoter). The data reported
for species A were obtained by comparing DNA from one member of species A to
another member of species A.
% Sequence Homology
Based on the tabular data, and assuming that time advances vertically, which
phylogenetic tree is the most likely depiction of the evolutionary relationships among
these five species?
A)
B)
C)
D)
Evolutionary trees such as this are properly understood by scientists to be _____.
A) theories
B) hypotheses
C) dogmas
D) facts
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
Which of the following takes place as an ice cube cools a drink?
A) Molecular collisions in the drink increase.
B) Kinetic energy in the liquid water decreases.
C) A calorie of heat energy is transferred from the ice to the water of the drink.
D) The specific heat of the water in the drink decreases.
Urea is produced in the _____.
A) liver from NH3 and carbon dioxide
B) liver from glycogen
C) kidneys from glycerol and fatty acids
D) bladder from uric acid and water
When antibodies bind antigens, the clumping of antigens results from _____.
A) the antibody having at least two binding regions
B) disulfide bridges between the antigens
C) bonds between class I and class II MHC molecules
D) denaturation of the antibodies
Canine phosphofructokinase (PFK) deficiency afflicts Springer spaniels, affecting an
estimated 10% of the breed. Given its critical role in glycolysis, one implication of the
genetic defect resulting in PFK deficiency in dogs is _____.
A) early embryonic mortality
B) elevated blood-glucose levels in the dog’s blood
C) an intolerance for exercise
D) a reduced life span
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
When oxygen is released as a result of photosynthesis, it is a direct by-product of
_____.
A) splitting water molecules
B) chemiosmosis
C) the electron transfer system of photosystem I
D) the electron transfer system of photosystem II
Organisms with a circulating body fluid that is distinct from the fluid that directly
surrounds the body’s cells are likely to have _____.
A) an open circulatory system
B) a closed circulatory system
C) a gastrovascular cavity
D) branched tracheae
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 one organ is an exaptation of another organ, then these two organs _____.
A) are homologous
B) are undergoing convergent evolution
C) are found in the same species
D) have the same function
Use the following information to answer the question(s) below.
Giardia intestinalis can cause disease in several different mammalian species, including
humans. Giardia organisms (G. intestinalis) that infect humans are similar
morphologically to those that infect other mammals; thus they have been considered a
single species. However, G. intestinalis has been divided into different subgroups based
on their host and a few other characteristics.
In 1999, a DNA sequence comparison study tested the hypothesis that these subgroups
actually constitute different species. The following phylogenetic tree was constructed
from the sequence comparison of rRNA from several subgroups of G. intestinalis and a
few other morphologically distinct species of Giardia. The researchers concluded that
the subgroups of Giardia are sufficiently different from one another genetically that
they could be considered different species. (T. Monis et al. 1999. Molecular systematics
of the parasitic protozoan Giardia intestinalis. Mol. Biol. Evol. 16[9]:1135-44.)
By examining the phylogenetic tree diagrammed in the figure above, what conclusion
can you draw about the species G. microti?
A) It evolved before G. intestinalis.
B) It is more closely related to G. muris than to G. intestinalis.
C) It should not be labeled a species distinct from G. intestinalis.
D) It is part of a monophyletic group that also includes G. intestinalis.