1883456
Pregunta 1
Pregunta
Darwinʹs mechanism of natural selection required long time spans in order to modify species. From whom did
Darwin get the concept of Earthʹs ancient age?
Respuesta
-
Georges Cuvier
-
Charles Lyell
-
Alfred Wallace
-
Thomas Malthus
-
John Henslow
Pregunta 2
Pregunta
Charles Darwin was the first person to propose
Respuesta
-
that evolution occurs.
-
a mechanism for how evolution occurs.
-
that the Earth is older than a few thousand years.
-
a mechanism for evolution that was supported by evidence.
-
a way to use artificial selection as a means of domesticating plants and animals.
Pregunta 3
Pregunta
Which of these conditions should completely prevent the occurrence of natural selection in a population over
time?
Respuesta
-
All variation between individuals is due only to environmental factors.
-
The environment is changing at a relatively slow rate.
-
The population size is large.
-
The population lives in a habitat where there are no competing species present.
Pregunta 4
Pregunta
Which of the following represents an idea that Darwin learned from the writings of Thomas Malthus?
Respuesta
-
All species are fixed in the form in which they are created.
-
Populations tend to increase at a faster rate than their food supply normally allows.
-
Earth changed over the years through a series of catastrophic upheavals.
-
The environment is responsible for natural selection.
-
Earth is more than 10,000 years old.
Pregunta 5
Pregunta
Given a population that contains genetic variation, what is the correct sequence of the following events, under
the influence of natural selection?
1. Well-adapted individuals leave more offspring than do poorly adapted individuals.
2. A change occurs in the environment.
3. Genetic frequencies within the population change.
4. Poorly adapted individuals have decreased survivorship.
Respuesta
-
2 → 4 → 1 → 3
-
4 → 2 → 1 → 3
-
4 → 1 → 2 → 3
-
4 → 2 → 3 → 1
-
2 → 4 → 3 → 1
Pregunta 6
Pregunta
To observe natural selectionʹs effects on a population, which of these must be true?
Respuesta
-
One must observe more than one generation of the population.
-
The population must contain genetic variation.
-
Members of the population must increase or decrease the use of some portion of their anatomy.
-
A and C only
-
A and B only
Pregunta 7
Pregunta
During drought years on the Galapagos, small, easily eaten seeds become rare, leaving mostly large,
hard-cased seeds that only birds with large beaks can eat. If a drought persists for several years, what should
one expect to result from natural selection?
Respuesta
-
Small birds gaining larger beaks by exercising their mouth parts.
-
Small birds mutating their beak genes with the result that later-generation offspring have larger beaks.
-
Small birds anticipating the long drought and eating more to gain weight and, consequently, growing larger beaks.
-
More small-beaked birds dying than larger-beaked birds. The offspring produced in subsequent generations have a higher percentage of birds with large beaks.
-
Larger birds eating less so smaller birds can survive
Pregunta 8
Pregunta
Which of the following must exist in a population before natural selection can act upon that population?
Respuesta
-
Genetic variation among individuals
-
Variation among individuals caused by environmental factors
-
Sexual reproduction
-
B and C only
-
A, B, and C
Pregunta 9
Pregunta
How many separate species, both extant and extinct, are depicted in this tree?
Respuesta
-
2
-
3
-
4
-
5
-
6
Pregunta 10
Pregunta
Which of the five common ancestors, labeled V—Z, has given rise to the greatest number of species, both extant
and extinct?
Respuesta
-
V
-
W
-
X
-
Y
-
Z
Pregunta 11
Pregunta
Evolutionary trees such as this are properly understood by scientists to be
Respuesta
-
theories.
-
hypotheses.
-
laws.
-
dogmas.
-
facts.
Pregunta 12
Pregunta
Which statement best describes the evolution of pesticide resistance in a population of insects?
Respuesta
-
Individual members of the population slowly adapt to the presence of the chemical by striving to meet the new challenge.
-
All insects exposed to the insecticide begin to use a formerly silent gene to make a new enzyme that breaks down the insecticide molecules.
-
Insects observe the behavior of other insects that survive pesticide application, and adjust their own behaviors to copy those of the survivors.
-
Offspring of insects that are genetically resistant to the pesticide become more abundant as the susceptible insects die off.
Pregunta 13
Pregunta
Some members of a photosynthetic plant species are genetically resistant to an herbicide, while other members
of the same species are not resistant to the herbicide. Which combination of events should cause the most
effective replacement of the non-herbicide-resistant strain of plants by the resistant strain?
1. The presence of the herbicide in the environment
2. The absence of the herbicide from the environment
3. The maintenance of the proper conditions for one generation
4. The maintenance of the proper conditions for many generations
Respuesta
-
1 and 3
-
1 and 4
-
2 and 3
-
2 and 4
Pregunta 14
Pregunta
Of the following anatomical structures, which is homologous to the wing of a bird?
Respuesta
-
Dorsal fin of a shark
-
Hindlimb of a kangaroo
-
Wing of a butterfly
-
Tail fin of a flying fish
-
Flipper of a cetacean
Pregunta 15
Pregunta
Structures as different as human arms, bat wings, and dolphin flippers contain many of the same bones, these
bones having developed from very similar embryonic tissues. How do biologists interpret these similarities?
Respuesta
-
By identifying the bones as being homologous
-
By the principle of convergent evolution
-
By proposing that humans, bats, and dolphins share a common ancestor
-
A and C only
-
A, B, and C
Pregunta 16
Pregunta
Which of the following pieces of evidence most strongly supports the common origin of all life on Earth?
Respuesta
-
All organisms require energy.
-
All organisms use essentially the same genetic code.
-
All organisms reproduce.
-
All organisms show heritable variation.
-
All organisms have undergone evolution.
Pregunta 17
Pregunta
Which of the following statements most detracts from the claim that the human appendix is a completely
vestigial organ?
Respuesta
-
The appendix can be surgically removed with no immediate ill effects.
-
The appendix might have been larger in fossil hominids.
-
The appendix has a substantial amount of defensive lymphatic tissue
-
Individuals with a larger-than-average appendix leave fewer offspring than those with a below-average-sized appendix.
-
In a million years, the human species might completely lack an appendix.
Pregunta 18
Pregunta
Ichthyosaurs were aquatic dinosaurs. Fossils show us that they had dorsal fins and tails, as do fish, even
though their closest relatives were terrestrial reptiles that had neither dorsal fins nor aquatic tails. The dorsal
fins and tails of ichthyosaurs and fish are
Respuesta
-
homologous.
-
examples of convergent evolution.
-
adaptations to a common environment.
-
A and C only
-
B and C only
Pregunta 19
Pregunta
Monkeys of South and Central America have prehensile tails, meaning that their tails can be used to grasp
objects. The tails of African and Asian monkeys are not prehensile. Which discipline is most likely to provide
an evolutionary explanation for how this difference in tails came about?
Respuesta
-
Aerodynamics
-
Biogeography
-
Physiology
-
Biochemistry
-
Botany
Pregunta 20
Pregunta
Heterozygote advantage should be most closely linked to which of the following?
Respuesta
-
sexual selection
-
stabilizing selection
-
random selection
-
directional selection
-
disruptive selection
Pregunta 21
Pregunta
In a single molecule of water, two hydrogen atoms are bonded to a single oxygen atom by
Respuesta
-
hydrogen bonds.
-
nonpolar covalent bonds.
-
polar covalent bonds.
-
ionic bonds.
-
van der Waals interactions.
Pregunta 22
Pregunta
An example of a hydrogen bond is the bond between
Respuesta
-
C and H in methane (CH4).
-
the H of one water molecule and the O of another water molecule.
-
Na+and Cl- in salt.
-
the two hydrogen atoms in a molecule of hydrogen gas (H2).
-
Mg+and Cl- in MgCl2.
Pregunta 23
Pregunta
What gives rise to the cohesiveness of water molecules?
Respuesta
-
hydrophobic interactions
-
nonpolar covalent bonds
-
ionic bonds
-
hydrogen bonds
-
both A and C
Pregunta 24
Pregunta
Which of the following takes place as an ice cube cools a drink?
Respuesta
-
Molecular collisions in the drink increase.
-
Kinetic energy in the drink decreases.
-
A calorie of heat energy is transferred from the ice to the water of the drink.
-
The specific heat of the water in the drink decreases.
-
Evaporation of the water in the drink increases.
Pregunta 25
Pregunta
The nutritional information on a cereal box shows that one serving of a dry cereal has 200 kilocalories. If one
were to burn one serving of the cereal, the amount of heat given off would be sufficient to raise the temperature
of 20 kg of water how many degrees Celsius?
Respuesta
-
0.2°C
-
1.0°C
-
2.0°C
-
10.0°C
-
20.0°C
Pregunta 26
Pregunta
Which type of bond must be broken for water to vaporize?
Respuesta
-
ionic bonds
-
nonpolar covalent bonds
-
polar covalent bonds
-
hydrogen bonds
-
covalent bonds
Pregunta 27
Pregunta
Hydrophobic substances such as vegetable oil are
Respuesta
-
nonpolar substances that repel water molecules.
-
nonpolar substances that have an attraction for water molecules.
-
polar substances that repel water molecules.
-
polar substances that have an affinity for water.
-
charged molecules that hydrogen-bond with water molecules.
Pregunta 28
Pregunta
One mole (mol) of a substance is
Respuesta
-
6.02 × 10^23 molecules of the substance.
-
1 g of the substance dissolved in 1 L of solution.
-
the largest amount of the substance that can be dissolved in 1 L of solution.
-
the molecular mass of the substance expressed in grams.
-
A and D only
Pregunta 29
Pregunta
When an ionic compound such as sodium chloride (NaCl) is placed in water the component atoms of the NaCl
crystal dissociate into individual sodium ions (Na+) and chloride ions (Cl-). In contrast, the atoms of covalently
bonded molecules (e.g., glucose, sucrose, glycerol) do not generally dissociate when placed in aqueous
solution. Which of the following solutions would be expected to contain the greatest number of particles
(molecules or ions)?
Respuesta
-
1 L of 0.5 M NaCl
-
1 L of 0.5 M glucose
-
1 L of 1.0 M NaCl
-
1 L of 1.0 M glucose
-
C and D will contain equal numbers of particles.
Pregunta 30
Pregunta
The molecular mass of glucose (C6H12O6) is 180 g. Which of the following procedures should you carry out to
make a 0.5 M solution of glucose?
Respuesta
-
Dissolve 0.5 g of glucose in a small volume of water, and then add more water until the total volume of solution is 1 L.
-
Dissolve 90 g of glucose in a small volume of water, and then add more water until the total volume of the solution is 1 L.
-
Dissolve 180 g of glucose in a small volume of water, and then add more water until the total volume of the solution is 1 L.
-
Dissolve 0.5 g of glucose in 1 L of water.
-
Dissolve 180 g of glucose in 1 L of water.
Pregunta 31
Pregunta
You have a freshly-prepared 0.1M solution of glucose in water. Each liter of this solution contains how many
glucose molecules?
Respuesta
-
6.02 × 10^23
-
3.01 × 10^23
-
6.02 × 10^24
-
12.04 × 10^23
-
6.02 × 10^22
Pregunta 32
Pregunta
You have a freshly-prepared 1M solution of glucose in water. You carefully pour out a 100 mL sample of that
solution. How many glucose molecules are included in that 100 mL sample?
Respuesta
-
6.02 × 10^23
-
3.01 × 10^23
-
6.02 × 10^24
-
12.04 × 10^23
-
6.02 × 10^22
Pregunta 33
Pregunta
Which of the following ionizes completely in solution and is considered to be a strong base (alkali)?
Respuesta
-
NaCl
-
HCl
-
NH3
-
H2CO3
-
NaOH
Pregunta 34
Pregunta
What is the pH of a solution with a hydroxyl ion [OH-] concentration of 10-12 M?
Respuesta
-
pH 4
-
pH 2
-
pH 6
-
pH 8
-
pH 10
Pregunta 35
Pregunta
Organic chemistry is a science based on the study of
Respuesta
-
functional groups.
-
vital forces interacting with matter.
-
carbon compounds.
-
water and its interaction with other kinds of molecules.
-
inorganic compounds.
Pregunta 36
Pregunta
The experimental approach taken in current biological investigations presumes that
Respuesta
-
simple organic compounds can be synthesized in the laboratory from inorganic precursors, but complex organic compounds like carbohydrates and proteins can only be synthesized by living organisms.
-
a life force ultimately controls the activities of living organisms and this life force cannot be studied by physical or chemical methods.
-
although a life force, or vitalism, exists in living organisms, this life force cannot be studied by physical or chemical methods.
-
living organisms are composed of the same elements present in nonliving things, plus a few special trace elements found only in living organisms or their products.
-
living organisms can be understood in terms of the same physical and chemical laws that can be used to explain all natural phenomena.
Pregunta 37
Pregunta
Which of the following people used this apparatus to study the formation of organic compounds?
Respuesta
-
Stanley Miller
-
Jakob Berzelius
-
Friedrich Wohler
-
Hermann Kolbe
-
August Kekulé
Pregunta 38
Pregunta
Which of the following people synthesized an organic compound, acetic acid, from inorganic substances that had been prepared directly from pure elements?
Respuesta
-
Stanley Miller
-
Jakob Berzelius
-
Friedrich Wohler
-
Hermann Kolbe
-
August Kekulé
Pregunta 39
Pregunta
How many electron pairs does carbon share in order to complete its valence shell?
Respuesta
-
1
-
2
-
3
-
4
-
8
Pregunta 40
Pregunta
The two molecules shown in the figure above are best described as
Respuesta
-
optical isomers.
-
enantiomers.
-
structural isomers.
-
cis-trans isomers.
-
chain length isomers.
Pregunta 41
Pregunta
The two molecules shown in the figure above are best described as
Respuesta
-
enantiomers.
-
radioactive isotopes.
-
structural isomers.
-
nonisotopic isomers
-
geometric isomers
Pregunta 42
Pregunta
Which of the following statements best describes the carbon atoms present in all organic molecules?
Respuesta
-
They were incorporated into organic molecules by plants.
-
They were processed into sugars through photosynthesis.
-
They are ultimately derived from carbon dioxide
-
Only A and C are correct.
-
A, B, and C are correct.
Pregunta 43
Pregunta
All of the following are part of a prokaryotic cell except:
Respuesta
-
DNA.
-
a cell wall
-
a plasma membrane.
-
ribosomes.
-
an endoplasmic reticulum.
Pregunta 44
Pregunta
Large numbers of ribosomes are present in cells that specialize in producing which of the following molecules?
Respuesta
-
lipids
-
glycogen
-
proteins
-
cellulose
-
nucleic acids
Pregunta 45
Pregunta
Which type of organelle or structure is primarily involved in the synthesis of oils, phospholipids, and steroids?
Respuesta
-
ribosome
-
lysosome
-
smooth endoplasmic reticulum
-
mitochondrion
-
contractile vacuole
Pregunta 46
Pregunta
The fact that the outer membrane of the nuclear envelope has bound ribosomes allows one to most reliably conclude that
Respuesta
-
at least some of the proteins that function in the nuclear envelope are made by the ribosomes on the nuclear envelope
-
the nuclear envelope is not part of the endomembrane system
-
the nuclear envelope is physically separated from the endoplasmic reticulum.
-
small vesicles from the Golgi fuse with the nuclear envelope
-
nuclear pore complexes contain proteins
Pregunta 47
Pregunta
Tay-Sachs disease is a human genetic abnormality that results in cells accumulating and becoming clogged with very large and complex lipids. Which cellular organelle must be involved in this condition?
Respuesta
-
the endoplasmic reticulum
-
the Golgi apparatus
-
the lysosome
-
mitochondria
-
membrane-bound ribosomes
Pregunta 48
Pregunta
Which of the following produces and modifies polysaccharides that will be secreted?
Respuesta
-
lysosome
-
vacuole
-
mitochondrion
-
Golgi apparatus
-
peroxisome
Pregunta 49
Pregunta
Which of the following contains hydrolytic enzymes?
Respuesta
-
lysosome
-
vacuole
-
mitochondrion
-
Golgi apparatus
-
peroxisome
Pregunta 50
Pregunta
Which organelle often takes up much of the volume of a plant cell?
Respuesta
-
lysosome
-
vacuole
-
mitochondrion
-
Golgi apparatus
-
peroxisome
Pregunta 51
Pregunta
Which plant cell organelle contains its own DNA and ribosomes?
Respuesta
-
glyoxysome
-
vacuole
-
mitochondrion
-
Golgi apparatus
-
peroxisome
Pregunta 52
Pregunta
Which animal cell organelle contains enzymes that transfer hydrogen from various substrates to oxygen?
Respuesta
-
lysosome
-
vacuole
-
mitochondrion
-
Golgi apparatus
-
peroxisome
Pregunta 53
Pregunta
The chemical reactions involved in respiration are virtually identical between prokaryotic and eukaryotic cells. In eukaryotic cells, ATP is synthesized primarily on the inner membrane of the mitochondria. In light of the endosymbiont theory for the evolutionary origin of mitochondria, where is most ATP synthesis likely to occur in prokaryotic cells?
Respuesta
-
in the cytoplasm
-
on the inner mitochondrial membrane
-
on the endoplasmic reticulum
-
on the inner plasma membrane
-
on the inner nuclear envelope
Pregunta 54
Pregunta
Which of the following are capable of converting light energy to chemical energy?
Respuesta
-
chloroplasts
-
mitochondria
-
leucoplasts
-
peroxisomes
-
Golgi bodies
Pregunta 55
Pregunta
A cell has the following molecules and structures: enzymes, DNA, ribosomes, plasma membrane, and
mitochondria. It could be a cell from
Respuesta
-
a bacterium.
-
an animal, but not a plant.
-
a plant, but not an animal.
-
a plant or an animal.
-
any kind of organism.
Pregunta 56
Pregunta
According to the fluid mosaic model of cell membranes, which of the following is a true statement about membrane phospholipids?
Respuesta
-
They can move laterally along the plane of the membrane.
-
They frequently flip-flop from one side of the membrane to the other.
-
They occur in an uninterrupted bilayer, with membrane proteins restricted to the surface of the membrane.
-
They are free to depart from the membrane and dissolve in the surrounding solution.
-
They have hydrophilic tails in the interior of the membrane
Pregunta 57
Pregunta
Which of the following would likely move through the lipid bilayer of a plasma membrane most rapidly?
Respuesta
-
CO2
-
an amino acid
-
glucose
-
K+
-
starch
Pregunta 58
Pregunta
Which of the following statements is correct about diffusion?
Respuesta
-
It is very rapid over long distances.
-
It requires an expenditure of energy by the cell.
-
It is a passive process in which molecules move from a region of higher concentration to a region of lower concentration.
-
It is an active process in which molecules move from a region of lower concentration to one of higher concentration.
-
It requires integral proteins in the cell membrane.
Pregunta 59
Pregunta
If a membrane protein in an animal cell is involved inthe cotransport of glucose and sodiumions into the cell, which of the following is most likely true?
Respuesta
-
The sodium ions are moving down their electrochemical gradient while glucose is moving up.
-
Glucose is entering the cell along its concentration gradient.
-
Sodium ions can move down their electrochemical gradient through the cotransporter whether or not glucose is present outside the cell.
-
Potassium ions move across the same gradient as sodium ions.
-
A substance that blocked sodium ions from binding to the cotransport protein would also block the transport of glucose.
Pregunta 60
Pregunta
Which of the following statements about xylem is incorrect?
Respuesta
-
It conducts material upward.
-
It conducts materials within dead cells.
-
It transports mainly sugars and amino acids.
-
It has a lower water potential than soil does.
-
No energy input from the plant is required for xylem transport.
Pregunta 61
Pregunta
Root hairs are most important to a plant because they
Respuesta
-
anchor a plant in the soil
-
store starches.
-
increase the surface area for absorption.
-
provide a habitat for nitrogen-fixing bacteria.
-
contain xylem tissue.
Pregunta 62
Pregunta
What is the role of proton pumps in root hair cells?
Respuesta
-
establish ATP gradients
-
acquire minerals from the soil
-
pressurize xylem transport
-
eliminate excess electrons
-
A and D only
Pregunta 63
Pregunta
A water molecule could move all the way through a plant from soil to root to leaf to air and pass through a living cell only once. This living cell would be a part of which structure?
Respuesta
-
the Casparian strip
-
a guard cell
-
the root epidermis
-
the endodermis
-
the root cortex
Pregunta 64
Pregunta
What is the main force by which most of the water within xylem vessels moves toward the top of a tree?
Respuesta
-
active transport of ions into the stele
-
atmospheric pressure on roots
-
evaporation of water through stoma
-
the force of root pressure
-
osmosis in the root
Pregunta 65
Pregunta
Which of the following are defenses that some plants use against herbivory?
Respuesta
-
production of the unusual amino acid canavanine
-
release of volatile compounds that attract parasitoid wasps
-
association of plant tissues with mycorrhizae
-
A and B only
-
A, B, and C
Pregunta 66
Pregunta
Plants are affected by an array of pathogens. Which of the following is not a plant defense against disease?
Respuesta
-
cells near the point of infection destroying themselves to prevent the spread of the infection
-
production of chemicals that kill pathogens
-
acquiring gene-for-gene recognition that allows specific proteins to interact so that the plant can produce defenses against the pathogen
-
a waxy cuticle that pathogens have trouble penetrating
-
All of the above are plant defenses against disease.
Pregunta 67
Pregunta
The transduction pathway that activates systemic acquired resistance in plants is initially signaled by
Respuesta
-
antisense RNA.
-
Pfr phytochrome.
-
salicylic acid.
-
abscisic acid.
-
red, but not far-red, light.
Pregunta 68
Pregunta
A short-day plant exposed to nights longer than the minimum for flowering but interrupted by short flashes of light will flower.
Respuesta
- True
- False
Pregunta 69
Pregunta
A long-day plant will flower only when the night is longer than a critical value.
Respuesta
- True
- False
Pregunta 70
Pregunta
An example of a properly functioning homeostatic control system is seen when
Respuesta
-
the level of glucose in the blood is abnormally high whether or not a meal has been eaten.
-
a blood cell shrinks when placed in a solution of salt and water.
-
the core body temperature of a runner rises gradually from 37°C to 45°C.
-
the kidneys excrete salt into the urine when dietary salt levels rise.
-
the blood pressure increases in response to an increase in blood volume.
Pregunta 71
Pregunta
Positive feedback has occurred when
Respuesta
-
an increase in blood sugar increases the secretion of a hormone that stimulates the movement of sugar out of the blood.
-
a decrease in blood sugar increases the secretion of a hormone that increases the conversion of glycogen to glucose.
-
uterine contractions needed for the birthing process are expedited by the pressure of a moving baby in its mother's uterus.
-
an increase in calcium concentration increases the secretion of a hormone that promotes the storage of calcium in bone.
-
a decrease in blood calcium increases the amount of the hormone that causes the release of calcium from bone.
Pregunta 72
Pregunta
In a survivably cold environment, an ectotherm is more likely to survive an extended period of food deprivation than would an equally sized endotherm because the ectotherm
Respuesta
-
invests little energy in temperature regulation.
-
has greater insulation on its body surface.
-
maintains a higher basal metabolic rate.
-
metabolizes its stored energy more readily than can the endotherm.
-
expends more energy per kg of body mass than does the endotherm.
Pregunta 73
Pregunta
Humans can lose, but cannot gain, heat through the process of
Respuesta
-
conduction.
-
evaporation.
-
radiation.
-
metabolism.
-
convection.
Pregunta 74
Pregunta
An example of an ectothermic organism that has few or no behavioral options when it comes to its ability to adjust its body temperature is a
Respuesta
-
sea star, a marine invertebrate.
-
bluefin tuna, a predatory fish.
-
terrestrial lizard.
-
honeybee in a hive.
-
hummingbird.
Pregunta 75
Pregunta
Endothermy
Respuesta
-
is only seen in mammals
-
is a term equivalent to "cold-blooded."
-
involves the production of heat through metabolism
-
is only seen in insects
-
is a characteristic of most animals
Pregunta 76
Pregunta
An example of an organism that has only behavioral controls over its body temperature is the
Respuesta
-
green frog.
-
penguin.
-
bluefin tuna
-
house sparrow.
-
gray wolf.
Pregunta 77
Pregunta
The temperature-regulating center of vertebrate animals is located in the
Respuesta
-
medulla oblongata.
-
thyroid gland.
-
hypothalamus.
-
subcutaneous layer of the skin.
-
liver
Pregunta 78
Pregunta
Ingested foods inside the digestive tract of snakes are typically digested by
Respuesta
-
biosynthesis.
-
enzymatic hydrolysis
-
uric acid.
-
chemiosmosis.
-
metabolic heat.
Pregunta 79
Pregunta
What does the difference in temperature between arteries and veins in the goose's legs indicate?
Respuesta
-
The legs need to be kept cool so that muscles will function well.
-
The feet need to be kept very warm so they do not freeze in water.
-
Heat loss is proportional to the difference in temperature inside and outside, so minimizing the difference means the goose will lose less heat.
-
Arterial blood helps return heat to the core of the goose.
-
Warm venous blood is necessary to keep the goose's feet from freezing.
Pregunta 80
Pregunta
Both the eye and the respiratory tract are protected against infections by which of the
following?
Respuesta
-
the secretion of lysozyme onto their surface
-
the mucous membranes that cover their surface
-
the secretion of complement proteins
-
the release of slightly acidic secretions
-
interferons produced by immune cells
Pregunta 81
Pregunta
Which statement about the complement system is true?
Respuesta
-
These proteins are involved in innate immunity and not acquired immunity.
-
These proteins are secreted by cytotoxic T cells and other CD8 cells.
-
This group of proteins includes interferons and interleukins.
-
These proteins are one group of antimicrobial proteins acting together in cascade fashion.
-
These proteins act individually to attack and lyse microbes.
Pregunta 82
Pregunta
Which cells and which signaling molecules are responsible for initiating an inflammatory response?
Respuesta
-
phagocytes: lysozymes
-
phagocytes: chemokines
-
dendritic cells: interferons
-
mast cells: histamines
-
lymphocytes: interferons
Pregunta 83
Pregunta
Septic shock, a systemic response including high fever and low blood pressure, is a response to
Respuesta
-
specific forms of viruses.
-
certain bacterial infections.
-
the presence of natural killer cells.
-
a fever of >103°F in adults.
-
increased production of neutrophils
Pregunta 84
Pregunta
If a newborn were accidentally given a drug that destroyed the thymus, what would most likely happen?
Respuesta
-
His cells would lack class I MHC molecules on their surface.
-
His immune system would not function.
-
Genetic rearrangement of antigen receptors would not occur.
-
His T cells would not mature and differentiate appropriately.
-
His B cells would be reduced in number.
Pregunta 85
Pregunta
The clonal selection theory is an explanation for how
Respuesta
-
a single type of stem cell can produce both red blood cells and white blood cells.
-
V gene and J gene segments are rearranged
-
an antigen can provoke development of very few cells to result in production of high levels of specific antibodies.
-
HIV can disrupt the immune system.
-
macrophages can recognize specific T cells and B cells.
Pregunta 86
Pregunta
When would B cells produce effector cells?
Respuesta
-
between 0 and 7 days
-
between 7 and 14 days
-
between 28 and 35 days
-
A and B
-
A and C
Pregunta 87
Pregunta
When would memory cells be produced?
Respuesta
-
between 0 and 7 days
-
between 7 and 14 days
-
between 28 and 35 days
-
between 35 and 42 days
-
both A and C
Pregunta 88
Pregunta
Which of the following differentiates T cells and B cells?
Respuesta
-
T cells but not B cells are stimulated to increase the rate of their cell cycles.
-
Only B cells are produced from stem cells of the bone marrow.
-
T cells but not B cells can directly attack and destroy invading pathogens.
-
T cells but not B cells have surface markers.
-
Only B cells take part in cell-mediated immunity.
Pregunta 89
Pregunta
The MHC is important in a T cell's ability to
Respuesta
-
recognize specific parasitic pathogens.
-
distinguish self from nonself.
-
identify specific bacterial pathogens.
-
identify specific viruses.
-
recognize differences among types of cancer.
Pregunta 90
Pregunta
The following events occur when a mammalian immune system first encounters a
pathogen. Which shows the correct sequence in which they occur?
I. Pathogen is destroyed.
II. Lymphocytes secrete antibodies.
III. Antigenic determinants from pathogen bind to antigen receptors on lymphocytes.
IV. Lymphocytes specific to antigenic determinants from pathogen become numerous.
V. Only memory cells remain.
Respuesta
-
I → III → II → IV → V
-
III → II → I → V → IV
-
II → I → IV → III → V
-
IV → II → III → I → V
-
III → IV → II → I → V
Pregunta 91
Pregunta
Which cell type interacts with both the humoral and cell-mediated immune
pathways?
Respuesta
-
plasma cells
-
helper T cells
-
natural killer cells
-
CD8 cells
-
cytotoxic T cells
Pregunta 92
Pregunta
Which of the following is accounted for by immunological memory?
Respuesta
-
the human body's ability to distinguish self from nonself
-
the observation that some strains of the pathogen that causes dengue fever cause worse disease than others
-
the ability of a helper T cell to signal B cells via cytokines
-
the ancient observation that someone who had recovered from the plague could safely care for those newly diseased
-
the ability of the immune system to present antigen fragments in association with MHC antigens
Pregunta 93
Pregunta
An otherwise healthy student in your class is infected with EBV, the virus that causes infectious
mononucleosis. The same student had already been infected when she was a child, and she had
merely experienced a mild sore throat and swollen lymph nodes in her neck. This time, though
infected, she does not get sick. The EBV antigen fragments will be presented by the virus-infected cells along with which of
the following?
Respuesta
-
complement
-
antibodies
-
class I MHC molecules
-
class II MHC molecules
-
Dendritic cells
Pregunta 94
Pregunta
A nonfunctional CD4 protein on a helper T cell would result in the helper T cell being unable
to
Respuesta
-
respond to T-independent antigens.
-
lyse tumor cells.
-
stimulate a cytotoxic T cell.
-
interact with a class I MHC-antigen complex
-
interact with a class II MHC-antigen complex.
Pregunta 95
Pregunta
Naturally acquired passive immunity would involve the
Respuesta
-
injection of vaccine.
-
ingestion of interferon.
-
placental transfer of antibodies.
-
absorption of pathogens through mucous membranes.
-
injection of antibodies.
Pregunta 96
Pregunta
What accounts for antibody switching (i.e., the switch of one B cell from producing one class
of antibody to another antibody class that is responsive to the same antigen)?
Respuesta
-
mutation in the genes of that B cell, induced by exposure to the antigen
-
the rearrangement of V region genes in that clone of responsive B cells
-
a switch in the kind of antigen-presenting cell that is involved in the immune response
-
a patient's reaction to the first kind of antibody made by the plasma cells
-
the shuffling of exons for one C region type to another attached to the V-J transcript
Pregunta 97
Pregunta
In which of the cases could the mother exhibit an anti-Rh-factor reaction to the
developing fetus?
Respuesta
-
Case 1 only
-
Case 3 only
-
Cases 1 and 2 only
-
Cases 1, 2, and 3
-
It cannot be determined from the data given.
Pregunta 98
Pregunta
When an individual is subject to short-term starvation, most available food is used to provide energy(metabolism) rather than building blocks (growth and repair). Which hormone would be particularly active intimes of food shortage?
Respuesta
-
epinephrine
-
glucagon
-
oxytocin
-
antidiuretic hormone
-
insulin
Pregunta 99
Pregunta
Based on their effects, which pair below could be considered antagonistic?
Respuesta
-
prostaglandin F and nitric oxide
-
growth hormone and ecdysone
-
endocrine and exocrine glands
-
hormones and target cells
-
neurosecretory cells and neurotransmitters
Pregunta 100
Pregunta
For this pair of items, choose the option that best describes their relationship.
(A) The number of purines in the DNA strand 5ʹ-AAGAGGAGAAA-3ʹ
(B) The number of pyrimidines in the DNA strand 5ʹ-AAGAGGAGAAA-3ʹ
Respuesta
-
Item (A) is greater than item (B).
-
Item (A) is less than item (B).
-
Item (A) is exactly or very approximately equal to item (B).
-
Item (A) may stand in more than one of the above relations to item (B).
Pregunta 101
Pregunta
Which of the following is not a polymer?
Respuesta
-
glucose
-
starch
-
cellulose
-
chitin
-
DNA
Pregunta 102
Pregunta
The molecular formula for glucose is C6H12O6. What would be the molecular formula for a
molecule made by linking three glucose molecules together by dehydration reactions?
Respuesta
-
C18H36O18
-
C18H30O15
-
C6H10O5
-
C18H10O15
-
C3H6O3
Pregunta 103
Pregunta
Which of the following descriptors is true of the molecule shown in Figure 5.1?
Respuesta
-
hexose
-
fructose
-
glucose
-
A and B only
-
A and C only
Pregunta 104
Pregunta
Which of the following statements is true regarding the molecule illustrated in Figure 5.2?
Respuesta
-
It is a saturated fatty acid.
-
A diet rich in this molecule may contribute to atherosclerosis.
-
Molecules of this type are usually liquid at room temperature.
-
A and B only
-
A, B and C
Pregunta 105
Pregunta
Which of the following statements is true regarding the molecule illustrated in Figure 5.3?
Respuesta
-
It is a saturated fatty acid.
-
A diet rich in this molecule may contribute to atherosclerosis.
-
Molecules of this type are usually liquid at room temperature
-
A and B only
-
A, B and C
Pregunta 106
Pregunta
What is the structure shown in Figure 5.4?
Respuesta
-
starch molecule
-
protein molecule
-
steroid molecule
-
cellulose molecule
-
phospholipid molecule
Pregunta 107
Pregunta
At which bond would water need to be added to achieve hydrolysis of the peptide, back to
its component amino acid?
Respuesta
-
A
-
B
-
C
-
D
-
E
Pregunta 108
Respuesta
-
A
-
B
-
C
-
D
-
E
Pregunta 109
Pregunta
Which bond is closest to the N-terminus of the molecule?
Respuesta
-
A
-
B
-
C
-
D
-
E
Pregunta 110
Pregunta
The structure depicted in Figure 5.7 shows the
Respuesta
-
1-4 linkage of the α glucose monomers of starch
-
1-4 linkage of the β glucose monomers of cellulose.
-
double helical structure of a DNA molecule.
-
α helix secondary structure of a polypeptide.
-
β pleated sheet secondary structure of a polypeptide
Pregunta 111
Pregunta
Which of the following best describes the flow of information in eukaryotic cells?
Respuesta
-
DNA → RNA → proteins
-
RNA → proteins → DNA
-
proteins → DNA → RNA
-
RNA → DNA → proteins
-
DNA → proteins → RNA
Pregunta 112
Pregunta
If a DNA sample were composed of 10% thymine, what would be the percentage of
guanine?
Respuesta
-
10
-
20
-
40
-
80
-
impossible to tell from the information given
Pregunta 113
Pregunta
If one strand of a DNA molecule has the sequence of bases 5ʹATTGCA3ʹ, the other
complementary strand would have the sequence
Respuesta
-
5ʹTAACGT3ʹ
-
3ʹTAACGT5ʹ.
-
5ʹUAACGU3ʹ
-
3ʹUAACGU5ʹ.
-
5ʹUGCAAU3ʹ.
Pregunta 114
Pregunta
Large numbers of ribosomes are present in cells that specialize in producing which of the following molecules?
Respuesta
-
lipids
-
starches
-
proteins
-
steroids
-
glucose
Pregunta 115
Pregunta
Under which of the following conditions would you expect to find a cell with a majority of "free" ribosomes (not connected to the ER)?
Respuesta
-
a cell that is secreting proteins
-
a cell that is producing cytoplasmic enzymes
-
a cell that is constructing its cell wall or extracellular matrix
-
a cell that is digesting food particles
-
a cell that is enlarging its vacuole
Pregunta 116
Pregunta
Which type of organelle is primarily involved in the synthesis of oils, phospholipids, and steroids?
Respuesta
-
smooth endoplasmic reticulum
-
lysosome
-
ribosome
-
mitochondrion
-
contractile vacuole
Pregunta 117
Pregunta
The Golgi apparatus has a polarity or sidedness to its structure and function. Which of the following statements CORRECTLY describes this polarity?
Respuesta
-
Transport vesicles fuse with one side of the Golgi and leave from the opposite side.
-
Proteins in in the membrane of the Golgi may be sorted and modified as they move from one side of the Golgi to the other.
-
Lipids in the membrane of the Golgi may be sorted and modified as they move from one side of the Golgi to the other.
-
Soluble proteins in the cisternae (interior) of the Golgi may be sorted and modified as they move from one side of the Golgi to the other.
-
All of the above correctly describe polar characteristics of the Golgi function.
Pregunta 118
Pregunta
Which structure is the site of the synthesis of proteins that may be exported from the cell?
Respuesta
-
rough ER
-
lysosomes
-
plasmodesmata
-
Golgi vesicles
-
free cytoplasmic ribosomes
Pregunta 119
Pregunta
In animal cells, hydrolytic enzymes are packaged to prevent general destruction of cellular components. Which of the following organelles functions in this compartmentalization?
Respuesta
-
chloroplast
-
lysosome
-
central vacuole
-
peroxisome
-
glyoxysome
Pregunta 120
Pregunta
Which of the following is a compartment that often takes up much of the volume of a plant cell?
Respuesta
-
lysosome
-
vacuole
-
mitochondrion
-
Golgi apparatus
-
peroxisome
Pregunta 121
Pregunta
Which is one of the main energy transformers of cells?
Respuesta
-
lysosome
-
vacuole
-
mitochondrion
-
Golgi apparatus
-
peroxisome
Pregunta 122
Pregunta
Which of the following contains enzymes that transfer hydrogen from various substrates to oxygen?
Respuesta
-
lysosome
-
vacuole
-
mitochondrion
-
Golgi apparatus
-
peroxisome
Pregunta 123
Pregunta
Grana, thylakoids, and stroma are all components found in
Respuesta
-
vacuoles.
-
chloroplasts.
-
mitochondria.
-
lysosomes.
-
nuclei.
Pregunta 124
Pregunta
A cell has the following molecules and structures: enzymes, DNA, ribosomes, plasma membrane, and mitochondria. It could be a cell from
Respuesta
-
a bacterium.
-
an animal, but not a plant.
-
a plant, but not an animal.
-
a plant or an animal
-
any kind of organism
Pregunta 125
Pregunta
Reactants capable of interacting to form products in a chemical reaction must first overcome a thermodynamic barrier known as the reaction's
Respuesta
-
entropy
-
activation energy.
-
equilibrium point.
-
endothermic level.
-
free-energy content.
Pregunta 126
Pregunta
Which curve represents the behavior of an enzyme taken from a bacterium that lives in hot springs at temperatures of 70oC or higher?
Respuesta
-
1
-
2
-
3
-
4
-
5
Pregunta 127
Pregunta
Which curve was most likely generated from analysis of an enzyme form a human stomach where conditions are strongly acidic?
Respuesta
-
1
-
2
-
3
-
4
-
5
Pregunta 128
Pregunta
Which of the following terms best describes the forward reaction in Figure 8.1?
Respuesta
-
endergonic, ∆G > 0
-
exergonic, ∆G < 0
-
endergonic, ∆G < 0
-
exergonic, ∆G > 0
-
chemical equilibrium, ∆G = 0
Pregunta 129
Pregunta
Assume that the reaction in Figure 8.1 has a ΔG of -5.6 kcal/mol. Which of the following would be true?
Respuesta
-
The reaction could be coupled to power an endergonic reaction with a ΔG of +6.2 kcal/mol.
-
The reaction could be coupled to power an exergonic reaction with a ΔG of +8.8 kcal/mol.
-
The reaction would result in a decrease in entropy (S) and an increase in the total energy content (H) of the system.
-
The reaction would result in an increase in entropy (S) and a decrease in the total energy content (H) of the system.
-
The reaction would result in products (C + D) with a greater free-energy content than in the initial reactants (A + B).
Pregunta 130
Pregunta
Paracrine signaling
Respuesta
-
involves secreting cells acting on nearby target cells by discharging a local regulator into the extracellular fluid.
-
requiresnerve cells to release a neurotransmitter into the synapse
-
occurs only in paracrine yeast cells.
-
has been found in plants but not animals.
-
involves mating factors attaching to target cells and causing production of new paracrine cells.
Pregunta 131
Pregunta
What would be true for the signaling system in an animal cell that lacks the ability to produce GTP?
Respuesta
-
It would not be able to activate and inactivate the G protein on the cytoplasmic side of the plasma membrane.
-
It could activate only the epinephrine system.
-
It would be able to carry out reception and transduction, but would not be able to respond to a signal.
-
Only A and C are true.
-
A, B, and C are true.
Pregunta 132
Pregunta
Up to 60% of all medicines used today exert their effects by influencing what structures in the cell membrane?
Respuesta
-
tyrosine-kinases receptors
-
ligand-gated ion channel receptors
-
growth factors
-
G proteins
-
cholesterol
Pregunta 133
Pregunta
Which of the following are chemical messengers that pass through the plasma membrane of cells & have receptor molecules in the cytoplasm?
Respuesta
-
Insulin
-
Testosterone
-
cAMP
-
Ephinephrine
Pregunta 134
Pregunta
A major group of G protein-coupled receptors contains seven transmembrane α helices. The amino end of the protein lies at the exterior of the plasma membrane. Loops of amino acids connect the helices either at the exterior face or on the cytosol face of the membrane. The loop on the cytosol side between helices 5 and 6 is usually substantially longer than the others.
Where would you expect to find the carboxyl end?
Respuesta
-
at the exterior surface
-
at the cytosol surface
-
connected with the loop at H5 and H6
-
between the membrane layers
Pregunta 135
Pregunta
One of the major categories of receptors in the plasma membrane reacts by forming dimers, adding phosphate groups, and then activating relay proteins. Which type does this?
Respuesta
-
G protein-coupled receptors
-
ligand-gated ion channels
-
steroid receptors
-
receptor tyrosine kinases
Pregunta 136
Pregunta
Sutherland discovered that epinephrine signals
Respuesta
-
a decrease in levels of cAMP as a result of bypassing the plasma membrane.
-
lower blood glucose by binding to liver cells.
-
interactions with insulin inside muscle cells.
-
interactions directly with glycogen phosphorylase.
-
elevation of cytosolic concentrations of cyclic AMP.
Pregunta 137
Pregunta
Which of the following describes cell communication systems?
Respuesta
-
Cell signaling evolved more recently than systems such as the immune system of vertebrates.
-
Communicating cells are usually close together.
-
Most signal receptors are bound to the outer membrane of the nuclear envelope.
-
Lipid phosphorylation is a major mechanism of signal transduction.
-
In response to a signal, the cell may alter activities by changes in cytosol activity or intranscription of RNA.
Pregunta 138
Pregunta
Which of the following most likely would be an immediate result of growth factor binding to its receptor?
Respuesta
-
protein kinase activity
-
adenylyl cyclase activity
-
GTPase activity
-
protein phosphatase activity
-
phosphorylase activity
Pregunta 139
Pregunta
Adenylyl cyclase has the opposite effect of which of the following?
Respuesta
-
protein kinase
-
protein phosphatase
-
phosphodiesterase
-
phosphorylase
-
GTPase
Pregunta 140
Pregunta
If a pharmaceutical company wished to design a drug to maintain low blood sugar levels, oneapproach might be to
Respuesta
-
design a compound that blocks epinephrine receptor activation.
-
design a compound that inhibits cAMP production in liver cells.
-
design a compound that inhibits phosphorylase activity.
-
design a compound to block G-protein activity in liver cells.
-
All of the above are possible approaches.
Pregunta 141
Pregunta
Which of the following statements is true?
Respuesta
-
When signal molecules first bind to receptor tyrosine kinases, the receptors phosphorylate anumber of nearby molecules
-
In response to some G-protein-mediated signals, a special type of lipid molecule associated with the plasma membrane is cleaved to form IP3 and calcium.
-
In most cases, signal molecules interact with the cell at the plasma membrane and then enter the cell and eventually the nucleus.
-
Toxins such as those that cause botulism and cholera interfere with the ability of activated G proteins to hydrolyze GTP to GDP, resulting in phosphodiesterase activity in the absence of an appropriate signal molecule.
-
Protein kinase A activation is one possible result of signal molecules binding to G protein-linked receptors.
Pregunta 142
Pregunta
One inhibitor of cGMP is Viagra. It provides a signal that leads to dilation of blood vesselsand increase of blood in the penis, facilitating erection. cGMP is inhibited, therefore the signal isprolonged. The original signal that is now inhibited would have
Respuesta
-
hydrolyzed cGMP to GMP.
-
hydrolyzed GTP to GDP
-
phosphorylated GDP.
-
dephosphorylated cGMP.
-
removed GMP from the cell.
Pregunta 143
Pregunta
The nucleus and most of the organelles in a neuron are located in the
Respuesta
-
dendritic region.
-
axon hillock.
-
axon.
-
cell body.
-
axon terminals
Pregunta 144
Pregunta
For a neuron with an initial membrane potential at -70 mV, an increase in the movement of potassium ions out of that neuron's cytoplasm would result in
Respuesta
-
the depolarization of the neuron
-
the hyperpolarization of the neuron
-
the replacement of potassium ions with sodium ions.
-
the replacement of potassium ions with calcium ions
-
the neuron switching on its sodium-potassium pump to restore the initial conditions
Pregunta 145
Pregunta
Although the membrane of a "resting" neuron is highly permeable to potassium ions, its membrane potential does not exactly match the equilibrium potential for potassium because the neuronal membrane is also
Respuesta
-
fully permeable to sodium ions.
-
slightly permeable to sodium ions
-
fully permeable to calcium ions.
-
impermeable to sodium ions
-
highly permeable to chloride ions.
Pregunta 146
Pregunta
The operation of the sodium-potassium "pump" moves
Respuesta
-
sodium and potassium ions into the cell.
-
sodium and potassium ions out of the ce
-
sodium ions into the cell and potassium ions out of the cell.
-
sodium ions out of the cell and potassium ions into the cell.
-
sodium and potassium ions into the mitochondria.
Pregunta 147
Pregunta
A "resting" motor neuron is expected to
Respuesta
-
release lots of acetylcholine.
-
have high permeability to sodium ions.
-
be equally permeable to sodium and potassium ions.
-
exhibit a resting potential that is more negative than the "threshold" potential.
-
have a higher concentration of sodium ions on the inside of the cell than on the outside
Pregunta 148
Pregunta
The "threshold" potential of a membrane
Respuesta
-
is the point of separation from a living to a dead neuron.
-
is the lowest frequency of action potentials a neuron can produce.
-
is the minimum hyperpolarization needed to prevent the occurrence of action potentials.
-
is the minimum depolarization needed to operate the voltage-gated sodium and potassium channels.
-
is the peak amount of depolarization seen in an action potential.
Pregunta 149
Pregunta
A toxin that binds specifically to voltage-gated sodium channels in axons would be expected to
Respuesta
-
prevent the hyperpolarization phase of the action potential.
-
prevent the depolarization phase of the action potential.
-
prevent graded potentials
-
increase the release of neurotransmitter molecules.
-
have most of its effects on the dendritic region of a neuron.
Pregunta 150
Pregunta
After the depolarization phase of an action potential, the resting potential is restored by
Respuesta
-
the opening of sodium activation gates.
-
the opening of voltage-gated potassium channels and the closing of sodium channels.
-
a decrease in the membrane's permeability to potassium and chloride ions.
-
a brief inhibition of the sodium-potassium pump
-
the opening of more voltage-gated sodium channels.
Pregunta 151
Pregunta
The membrane potential is closest to the equilibrium potential for potassium at label
Respuesta
-
A
-
B
-
C
-
D
-
E
Pregunta 152
Pregunta
The membrane's permeability to sodium ions is at its maximum at label
Respuesta
-
A
-
B
-
C
-
D
-
E
Pregunta 153
Pregunta
The minimum graded depolarization needed to operate the voltage-gated sodium and potassium channels is indicated by the label
Respuesta
-
A
-
B
-
C
-
D
-
E
Pregunta 154
Pregunta
The cell is not hyperpolarized; however, repolarization is in progress, as the sodium channels are closing or closed, and many potassium channels have opened at label
Respuesta
-
A
-
B
-
C
-
D
-
E
Pregunta 155
Pregunta
The neuronal membrane is at its resting potential at label
Respuesta
-
A
-
B
-
C
-
D
-
E
Pregunta 156
Pregunta
In the sequence of permeability changes for a complete action potential, the first of these events that occurs is
Respuesta
-
the activation of the sodium-potassium "pump."
-
the inhibition of the sodium-potassium "pump."
-
the opening of voltage-gated sodium channels.
-
the closing of voltage-gated potassium channels.
-
the opening of voltage-gated potassium channels.
Pregunta 157
Pregunta
Neurotransmitters are released from axon terminals via
Respuesta
-
osmosis.
-
active transport.
-
diffusion.
-
transcytosis.
-
exocytosis.
Pregunta 158
Pregunta
The observation that the acetylcholine released into the junction between a motor neuron and a skeletal muscle binds to a sodium channel and opens it is an example of
Respuesta
-
a voltage-gated sodium channel.
-
a voltage-gated potassium channel.
-
a ligand-gated sodium channel.
-
a second-messenger-gated sodium channel.
-
a chemical that inhibits action potentials.
Pregunta 159
Pregunta
An inhibitory postsynaptic potential (IPSP) occurs in a membrane made more permeable to
Respuesta
-
potassium ions.
-
sodium ions.
-
calcium ions.
-
ATP.
-
all neurotransmitter molecules.
Pregunta 160
Pregunta
The activity of acetylcholine in a synapse is terminated by
Respuesta
-
its active transport across the presynaptic membrane.
-
its diffusion across the presynaptic membrane.
-
its active transport across the postsynaptic membrane
-
its diffusion across the postsynaptic membrane.
-
its degradation by a hydrolytic enzyme on the postsynaptic membrane
Pregunta 161
Pregunta
When several EPSPs arrive at the axon hillock from different dendritic locations, depolarizing the postsynaptic cell to threshold for an action potential, this is an example of
Respuesta
-
temporal summation.
-
spatial summation.
-
tetanus.
-
the refractory state.
-
an action potential with an abnormally high peak of depolarization.
Pregunta 162
Pregunta
Functionally, which cellular location is the neuron's "decision-making site" as to whether or not an action potential will be initiated?
Respuesta
-
axonal membranes
-
axon hillocks
-
dendritic membranes
-
mitochondrial membranes
-
presynaptic membranes
Pregunta 163
Pregunta
Which of the following types of reactions would decrease the entropy within a cell?
Respuesta
-
respiration
-
dehydration reactions
-
hydrolysis
-
catabolism
-
digestion
Pregunta 164
Pregunta
Which of the following is an example of potential rather than kinetic energy?
Respuesta
-
the muscle contractions of a person mowing grass
-
water rushing over Niagara Falls
-
light flashes emitted by a firefly
-
a molecule of glucose
-
the flight of an insect foraging for food
Pregunta 165
Pregunta
Which of the following is true of metabolism in its entirety in all organisms?
Respuesta
-
Metabolism depends on a constant supply of energy from food.
-
Metabolism depends on an organism's adequate hydration.
-
Metabolism uses all of an organism's resources.
-
Metabolism is a property of organismal life.
-
Metabolism manages the increase of entropy in an organism.
Pregunta 166
Pregunta
What is the change in free energy of a system at chemical equilibrium?
Respuesta
-
slightly increasing
-
greatly increasing
-
slightly decreasing
-
greatly decreasing
-
no net change
Pregunta 167
Pregunta
Chemical equilibrium is relatively rare in living cells. Which of the following could be an example of a reaction at chemical equilibrium in a cell?
Respuesta
-
a reaction in which the free energy at equilibrium is higher than the energy content at any point away from equilibrium
-
a chemical reaction in which the entropy change in the reaction is just balanced by an opposite entropy change in the cell's surroundings
-
an endergonic reaction in an active metabolic pathway where the energy for that reaction is supplied only by heat from the environment
-
a chemical reaction in which both the reactants and products are not being produced or used in any active metabolic pathway
-
no possibility of having chemical equilibrium in any living cell
Pregunta 168
Pregunta
When glucose monomers are joined together by glycosidic linkages to form a cellulose polymer, the changes in free energy, total energy, and entropy are as follows:
Respuesta
-
+ΔG, +ΔH, +ΔS.
-
+ΔG, +ΔH, -ΔS.
-
+ΔG, -ΔH, -ΔS.
-
-ΔG, +ΔH, +ΔS.
-
-ΔG, -ΔH, -ΔS
Pregunta 169
Pregunta
Which of the following best describes enthalpy (H)?
Respuesta
-
the total kinetic energy of a system
-
the heat content of a chemical system
-
the system's entropy
-
the cell's energy equilibrium
-
the condition of a cell that is not able to react
Pregunta 170
Pregunta
When 10,000 molecules of ATP are hydrolyzed to ADP and Pi in a test tube, about twice as much heat is liberated as when a cell hydrolyzes the same amount of ATP. Which of the following is the best explanation for this observation?
Respuesta
-
Cells are open systems, but a test tube is a closed system.
-
Cells are less efficient at heat production than nonliving systems.
-
The hydrolysis of ATP in a cell produces different chemical products than does the reaction in a test tube.
-
The reaction in cells must be catalyzed by enzymes, but the reaction in a test tube does not need enzymes.
-
Reactant and product concentrations in the test tube are different from those in the cell.
Pregunta 171
Pregunta
What term is used to describe the transfer of free energy from catabolic pathways to anabolic pathways?
Respuesta
-
feedback regulation
-
bioenergetics
-
energy coupling
-
entropy
-
cooperativity
Pregunta 172
Pregunta
When chemical, transport, or mechanical work is done by an organism, what happens to the heat generated?
Respuesta
-
It is used to power yet more cellular work.
-
It is used to store energy as more ATP.
-
It is used to generate ADP from nucleotide precursors.
-
It is lost to the environment.
-
It is transported to specific organs such as the brain.
Pregunta 173
Pregunta
A number of systems for pumping across membranes are powered by ATP. Such ATP-powered pumps are often called ATPases although they don't often hydrolyze ATP unless they are simultaneously transporting ions. Small increases in calcium ions in the cytosol trigger a number of different intracellular reactions, so the cells must keep the calcium concentration quite low. Muscle cells also transport calcium from the cytosol into the membranous system called the sarcoplasmic reticulum (SR). If a muscle cell cytosol has a free calcium ion concentration of 10-7 in a resting cell, while the concentration in the SR can be 10-2, then how is the ATPase acting?
Respuesta
-
The ATP must be powering an inflow of calcium from the outside of the cell into the SR
-
ATP must be transferring Pi to the SR to enable this to occur.
-
ATPase activity must be pumping calcium from the cytosol to the SR against the concentration gradient.
-
The calcium ions must be diffusing back into the SR along the concentration gradient.
-
The route of calcium ions must be from SR to the cytosol, to the cell's environment.
Pregunta 174
Pregunta
What is the term for metabolic pathways that release stored energy by breaking down complex molecules?
Respuesta
-
anabolic pathways
-
catabolic pathways
-
fermentation pathways
-
thermodynamic pathways
-
bioenergetic pathways
Pregunta 175
Pregunta
Which of the following statements describes the results of this reaction?
C₆H₁₂O₆ + 6 O₂ → 6 CO₂ + 6 H₂O + Energy
Respuesta
-
C₆H₁₂O₆ is oxidized and O₂ is reduced.
-
O₂ is oxidized and H₂O is reduced.
-
CO₂ is reduced and O₂ is oxidized
-
C₆H₁₂O₆ is reduced and CO₂ is oxidized.
-
O₂ is reduced and CO₂ is oxidized
Pregunta 176
Pregunta
Where does glycolysis take place in eukaryotic cells?
Respuesta
-
mitochondrial matrix
-
mitochondrial outer membrane
-
mitochondrial inner membrane
-
mitochondrial intermembrane space
-
cytosol
Pregunta 177
Pregunta
Which step in Figure 9.1 shows a split of one molecule into two smaller molecules?
Respuesta
-
A
-
B
-
C
-
D
-
E
Pregunta 178
Pregunta
Starting with one molecule of glucose, the "net" products of glycolysis are
Respuesta
-
2 NAD⁺, 2 pyruvate, and 2 ATP
-
2 NADH, 2 pyruvate, and 2 ATP
-
2 FADH₂, 2 pyruvate, and 4 ATP
-
6 CO₂, 2 ATP, and 2 pyruvate.
-
6 CO₂, 30 ATP, and 2 pyruvate
Pregunta 179
Pregunta
Why is glycolysis described as having an investment phase and a payoff phase?
Respuesta
-
It both splits molecules and assembles molecules
-
It attaches and detaches phosphate groups.
-
It uses glucose and generates pyruvate.
-
It shifts molecules from cytosol to mitochondrion.
-
It uses stored ATP and then forms a net increase in ATP
Pregunta 180
Pregunta
In the presence of oxygen, the three-carbon compound pyruvate can be catabolized in the citric acid cycle. First, however, the pyruvate (1) loses a carbon, which is given off as a molecule of CO₂, (2) is oxidized to form a two-carbon compound called acetate, and (3) is bonded to coenzyme A.
These three steps result in the formation of
Respuesta
-
acetyl CoA, O₂, and ATP.
-
acetyl CoA, FADH₂, and CO₂
-
acetyl CoA, FAD, H₂, and CO₂.
-
acetyl CoA, NADH, H⁺, and CO₂.
-
acetyl CoA, NAD⁺, ATP, and CO₂
Pregunta 181
Pregunta
How many molecules of carbon dioxide (CO2) would be produced by five turns of the citric acid cycle?
Respuesta
-
2
-
5
-
10
-
12
-
60
Pregunta 182
Pregunta
Which of the following describes the sequence of electron carriers in the electron transport chain, starting with the least electronegative?
Respuesta
-
ubiquinone (Q), cytochromes (Cyt), FMN, Fe•S
-
cytochromes (Cyt), FMN, ubiquinone, Fe∙S
-
Fe•S, FMN, cytochromes (Cyt), ubiquinone
-
FMN, Fe•S, ubiquinone, cytochromes (Cyt)
-
cytochromes (Cyt), Fe•S, ubiquinone, FMN
Pregunta 183
Pregunta
Where does the Calvin cycle take place?
Respuesta
-
stroma of the chloroplast
-
thylakoid membrane
-
cytoplasm surrounding the chloroplast
-
interior of the thylakoid (thylakoid space)
-
outer membrane of the chloroplast
Pregunta 184
Pregunta
When oxygen is released as a result of photosynthesis, it is a direct by-product of
Respuesta
-
reducing NADP⁺.
-
splitting water molecules.
-
chemiosmosis.
-
the electron transfer system of photosystem I
-
the electron transfer system of photosystem II.
Pregunta 185
Pregunta
Figure 10.1 shows the absorption spectrum for chlorophyll a and the action spectrum for photosynthesis. Why are they different?
Respuesta
-
Green and yellow wavelengths inhibit the absorption of red and blue wavelengths.
-
Bright sunlight destroys photosynthetic pigments.
-
Oxygen given off during photosynthesis interferes with the absorption of light.
-
Other pigments absorb light in addition to chlorophyll a.
-
Aerobic bacteria take up oxygen, which changes the measurement of the rate of photosynthesis.
Pregunta 186
Pregunta
Assume a thylakoid is somehow punctured so that the interior of the thylakoid is no longer separated from the stroma. This damage will have the most direct effect on which of the following processes?
Respuesta
-
the splitting of water
-
the absorption of light energy by chlorophyll
-
the flow of electrons from photosystem II to photosystem I
-
the synthesis of ATP
-
the reduction of NADP⁺
Pregunta 187
Pregunta
In mitochondria, chemiosmosis translocates protons from the matrix into the intermembranespace, whereas in chloroplasts, chemiosmosis translocates protons from
Respuesta
-
the stroma to the photosystem II.
-
the matrix to the stroma.
-
the stroma to the thylakoid space.
-
the intermembrane space to the matrix.
-
ATP synthase toNADP+ reductase.
Pregunta 188
Pregunta
In thylakoids, protons travel through ATP synthase from the stroma to the thylakoid space.Therefore the catalytic "knobs" of ATP synthase would be located
Respuesta
-
on the side facing the thylakoid space
-
on the ATP molecules themselves.
-
on the pigment molecules of PSI and PSII.
-
on the stroma side of the membrane.
-
built into the center of the thylkoid stack (granum).
Pregunta 189
Pregunta
Compare the light reactions with the Calvin cycle of photosynthesis in plants.
Produces NADH:
Respuesta
-
light reactions alone
-
the Calvin cycle alone
-
both the light reactions and the Calvin cycle
-
neither the light reactions nor the Calvin cycle
-
occurs in the chloroplast but is not part of photosynthesis
Pregunta 190
Pregunta
Compare the light reactions with the Calvin cycle of photosynthesis in plants.
Requires glucose:
Respuesta
-
light reactions alone
-
the Calvin cycle alone
-
both the light reactions and the Calvin cycle
-
neither the light reactions nor the Calvin cycle
-
occurs in the chloroplast but is not part of photosynthesis
Pregunta 191
Pregunta
The sugar that results from three "turns" of the Calvin cycle is glyceraldehyde-3-phosphate
(G3P). Which of the following is a consequence of this?
Respuesta
-
Formation of a moleculeof glucose would require 9 "turns."
-
G3P more readily forms sucrose and other disaccharides than it does monosaccharides.
-
Some plants would not taste sweet to us.
-
The formation of starch in plants involves assembling many G3P molecules, with or without further rearrangements.
-
G3P is easier for a plant to store.
Pregunta 192
Pregunta
If ATP used by this plant is labeled with radioactive phosphorus, which molecules will the radioactivity be measurable after one "turn" of the cycle?
Respuesta
-
B only
-
B and C only
-
B, C, and D only
-
B and E only
-
B, C, D, and E
Pregunta 193
Pregunta
If the carbon atom of the incoming CO₂ molecule is labeled with a radioactive isotope of carbon, which organic molecules will be radioactively labeled after one cycle?
Respuesta
-
E only
-
B, C, D, and E
-
C, D, and E only
-
B and C only
-
B and D only
Pregunta 194
Pregunta
Which molecule(s) of the Calvin cycle is (are) also found in glycolysis?
Respuesta
-
A only
-
C and D only
-
A, B, C, and E
-
B, C, and E
-
E only
Pregunta 195
Pregunta
Evolutionary adaptations that help diverse animals directly exchange matter between cells and the environment include
Respuesta
-
a gastrovascular activity, a two-layered body, and a torpedo-like body shape.
-
an external respiratory surface, a small body size, and a two-cell-layered body.
-
a large body volume; a long, tubular body; and a set of wings.
-
complex internal structures, a small body size, and a large surface area.
-
an unbranched internal surface, a small body size, and thick covering.
Pregunta 196
Pregunta
Hibernation and estivation are both examples of
Respuesta
-
acclimatization.
-
torpor.
-
evaporative cooling
-
nonshivering thermogenesis.
-
shivering thermogenesis.
Pregunta 197
Pregunta
If you gently twist your earlobe, it does not remain distorted because it contains
Respuesta
-
collagenous fibers.
-
elastin fibers.
-
reticular fibers.
-
adipose tissue.
-
loose connective tissue.
Pregunta 198
Pregunta
Endothermy
Respuesta
-
is a characteristic of most animals
-
involves the production of heat through metabolism
-
is only seen in insects
-
is a term equivalent to "cold-blooded"
-
is only seen in mammals
Pregunta 199
Pregunta
The best time to measure the metabolic rate is when the animal
Respuesta
-
is resting and has not eaten its first meal of the day.
-
is resting and has just completed its first meal of the day.
-
has recently eaten a sugar-free meal.
-
has not consumed any water for at least 48 hours.
-
has just completed 30 minutes of vigorous exercise.
¿Quieres crear tus propios Tests gratis con GoConqr? Más información.