The ovary is most often located on/in the
A) stamen.
B) carpel.
C) petals.
D) sepals.
E) receptacle

B)

In some angiosperms, other floral parts contribute to what is commonly called the fruit. Which of the following fruits is derived mostly from an enlarged receptacle?
A) pea
B) raspberry
C) apple
D) pineapple
E) peach

C)

In the life cycle of an angiosperm, which of the following stages is diploid?
A) megaspore
B) generative nucleus of a pollen grain
C) polar nuclei of the embryo sac
D) microsporocyte
E) both megaspore and polar nuclei

D)

Three mitotic divisions within the female gametophyte of the megaspore produce
A) three antipodal cells, two polar nuclei, one egg, and two synergids.
B) the triple fusion nucleus.
C) three pollen grains.
D) two antipodal cells, two polar nuclei, two eggs, and two synergids.
E) a tube nucleus, a generative cell, and a sperm cell.

A)

What is the first step in the germination of a seed?
A) pollination
B) fertilization
C) imbibition
D) hydrolysis of starch and other food reserves
E) emergence of the radicle

C)

Which of the following conclusions is supported by the research of both Went and Charles and Francis Darwin on shoot responses to light?
A) When shoots are exposed to light, a chemical substance migrates toward the light.
B) Agar contains a chemical substance that mimics a plant hormone.
C) A chemical substance involved in shoot bending is produced in shoot tips.
D) Once shoot tips have been cut, normal growth cannot be induced.
E) Light stimulates the synthesis of a plant hormone that responds to light

C)

When growing plants in culture, IAA is used to stimulate cell enlargement. Which plant growth regulator has to now be added to stimulate cell division?
A) ethylene
B) indoleacetic acid
C) gibberellin
D) cytokinin
E) abscisic acid

D)

Interstitial fluid is
A) the fluid inside the gastrovascular cavity of Hydra.
B) the internal environment inside animal cells.
C) identical to the composition of blood.
D) the route for the exchange of materials between blood and body cells.
E) found only in the lumen of the small intestine.

D)

Tissues are composed of cells, and tissues functioning together make up
A) organs.
B) membranes.
C) organ systems.
D) organelles.
E) organisms

A)

An example of a connective tissue is the
A) skin.
B) nerves.
C) blood.
D) cuboidal epithelium.
E) smooth muscles.

C)

Muscles are joined to bones by
A) ligaments.
B) tendons.
C) loose connective tissue.
D) Haversian systems.
E) spindle fibers.

B)

In a typical nerve cell, the nucleus is found in the
A) cell body.
B) synaptic terminals.
C) axonal region.
D) dendritic region.
E) synapse.

A)

All skeletal muscle fibers are both
A) smooth and under involuntary control.
B) smooth and operate independently of other skeletal muscle fibers.
C) striated and under voluntary control.
D) smooth and under voluntary control.
E) striated and electrically coupled to neighboring fibers.

C)

The body's automatic tendency to maintain a constant and optimal internal environment is termed
A) balanced equilibrium.
B) physiological chance.
C) homeostasis.
D) static equilibrium.
E) estivation

C)

Endothermy
A) is a characteristic of most animals found in tropical zones.
B) is a characteristic of animals that have a fairly constant body temperature.
C) is a term equivalent to cold-blooded.
D) is a characteristic of mammals but not of birds.
E) is seen only in insects and in certain predatory fishes

B)

Hibernation and estivation are both examples of
A) acclimatization.
B) torpor.
C) evaporative cooling.
D) nonshivering thermogenesis.
E) shivering thermogenesis

B)

Folic acid supplements have become especially important for pregnant women because
A) folic acid supplies vitamins that only pregnant women can use.
B) the folic acid is stored in adipose tissue by pregnant women so supplements are needed to make more available in the circulation.
C) the fetus makes high levels of folic acid.
D) folic acid deprivation is associated with neural tube abnormalities in a fetus.
E) folic acid deprivation is a cause of heart abnormalities in a newborn.

D)

intracellular digestion of peptides is usually immediately preceded by
A) hydrolysis.
B) endocytosis.
C) absorption.
D) elimination.
E) secretion.

B)

Fat digestion yields fatty acids and glycerol, whereas protein digestion yields amino acids; both digestive processes
A) are catalyzed by the same enzyme.
B) are excludible intracellular processes in most organisms.
C) add a water molecule to break bonds (hydrolysis).
D) require the presence of hydrochloric acid to lower the pH.
E) require ATP as an energy source.

C)

Among mammals, it is generally true that
A) all types of foods begin their enzymatic digestion in the mouth.
B) after leaving the oral cavity, the bolus enters the larynx.
C) the epiglottis prevents swallowed food from entering the trachea.
D) the esophagus is a key source of digestive enzymes.
E) the trachea leads to the esophagus and then to the stomach.

C)

The absorption of fats differs from that of carbohydrates in that the
A) processing of fats does not require any digestive enzymes, whereas the processing of carbohydrates does.
B) fat absorption occurs in the stomach, whereas carbohydrates are absorbed from the small intestine.
C) carbohydrates need to be emulsified before they can be digested, whereas fats do not.
D) most absorbed fat first enters the lymphatic system, whereas carbohydrates directly enter the blood.
E) fats, but not carbohydrates, are digested by bacteria before absorption.

D)

The cells that secrete acidic fluid in the stomach are
A) the chief cells of the stomach.
B) the parietal cells of the stomach.
C) not needed for the transformation of pepsinogen to pepsin.
D) in the lumen of the stomach.
E) adding secretions along the esophagus

D)

To adjust blood pressure independently in the capillaries of the gas-exchange surface and in the capillaries of the general body circulation, an organism would need a(n)
A) open circulatory system.
B) hemocoel.
C) lymphatic system.
D) two-chambered heart.
E) four-chambered heart.

E)

A patient with a blood pressure of 120/75, a pulse rate of 40 beats/minute, a stroke volume of 70 mL/beat, and a respiratory rate of 25 breaths/minute will have a cardiac output of
A) 500 mL/minute.
B) 1,000 mL/minute.
C) 1,750 mL/minute.
D) 2,800 mL/minute.
E) 4,800 mL/minute.

D)

Damage to the sinoatrial node in humans
A) is a major contributor to heart attacks.
B) would block conductance between the bundle branches and the Purkinje fibers.
C) would have a negative effect on peripheral resistance.
D) would disrupt the rate and timing of cardiac muscle contractions.
E) would have a direct effect on blood pressure monitors in the aorta.

D)

Large proteins such as albumin remain in capillaries rather than diffusing out, resulting in the
A) loss of osmotic pressure in the capillaries.
B) development of an osmotic pressure difference across capillary walls.
C) loss of fluid from capillaries.
D) increased diffusion of CO2.
E) increased diffusion of Hb.

B)

During most daily activities, the human respiration rate is most closely linked to the blood levels of
A) nitric acid.
B) nitrogen.
C) oxygen.
D) carbon dioxide.
E) carbon monoxide

D)

The Bohr shift on the oxygen-hemoglobin dissociation curve is produced by changes in
A) the partial pressure of oxygen.
B) the partial pressure of carbon monoxide.
C) hemoglobin concentration.
D) temperature.
E) pH.

E)

The eyes and the respiratory tract are both protected against infections by
A) the mucous membranes that cover their surface.
B) the secretion of complement proteins.
C) the release of slightly alkaline secretions.
D) the secretion of lysozyme onto their surfaces.
E) interferons produced by immune cells.

D)

Clonal selection is an explanation for how
A) a single type of stem cell can produce both red blood cells and white blood cells.
B) V, J, and C gene segments are rearranged.
C) an antigen can provoke production of high levels of specific antibodies.
D) HIV can disrupt the immune system.
E) macrophages can recognize specific T cells and B cells.

C)

Arrange these components of the mammalian immune system as it first responds to a pathogen in the correct sequence.

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.

A) I → III → II → IV → V
B) III → II → I → V → IV
C) II → I → IV → III → V
D) IV → II → III → I → V
E) III → IV → II → I → V

E)

The primary function of humoral immunity is
A) to defend against fungi and protozoa.
B) to reject transplanted tissues.
C) to protect the body against cells that become cancerous.
D) to protect the body against extracellular pathogens.
E) to defend against bacteria and viruses that have already infected cells.

D)

Naturally acquired passive immunity results from the
A) injection of vaccine.
B) ingestion of interferon.
C) placental transfer of antibodies.
D) absorption of pathogens through mucous membranes.
E) injection of antibodies.

C)

Unlike most bony fishes, sharks maintain body fluids that are isoosmotic to seawater, so they are considered by many to be osmoconformers. Nonetheless, these sharks osmoregulate at least partially by
A) using their gills and kidneys to rid themselves of sea salts.
B) monitoring dehydration at the cellular level with special gated aquaporins.
C) tolerating high urea concentrations that balance internal salt concentrations to seawater osmolarity.
D) synthesizing trimethylamine oxide, a chemical that binds and precipitates salts inside cells.
E) possessing a special adaptation that allows their cells to operate at an extraordinarily high salt concentration.

C)

3Urea is produced in the
A) liver from NH₃ and CO₂.
B) liver from glycogen.
C) kidneys from glucose.
D) kidneys from glycerol and fatty acids.
E) bladder from uric acid and H₂O.

A)

The advantage of excreting nitrogenous wastes as urea rather than as ammonia is that
A) urea can be exchanged for Na+.
B) urea is less toxic than ammonia.
C) urea requires more water for excretion than ammonia.
D) urea does not affect the osmolar gradient.
E) less nitrogen is removed from the body.

B)

The most concentrated urine is excreted by
A) frogs.
B) kangaroo rats.
C) humans.
D) desert tortoises.
E) birds.

B)

Materials are returned to the blood from the filtrate by which of the following processes?
A) filtration
B) ultrafiltration
C) selective reabsorption
D) secretion
E) active transport

C)

Excretory structures known as protonephridia are present in
A) flatworms.
B) earthworms.
C) insects.
D) vertebrates.
E) cnidarians.

A)

Choose a pair that correctly associates the mechanism for osmoregulation or nitrogen removal with the appropriate animal.
A) metanephridiumflatworm
B) Malpighian tubulefrog
C) kidneyinsect
D) flame bulbsnake
E) exchange across body surfacemarine invertebrate

E)

Within a normally functioning nephron, blood can be found in
A) the vasa recta.
B) Bowman's capsule.
C) the loop of Henle.
D) the proximal tubule.
E) the collecting duct.

A)

Processing of filtrate in the proximal and distal tubules
A) achieves the sorting of plasma proteins according to size.
B) achieves the conversion of toxic ammonia to less toxic urea.
C) maintains homeostasis of pH in body fluids.
D) regulates the speed of blood flow through the nephrons.
E) reabsorbs urea to maintain osmotic balance.

C)

After drinking alcoholic beverages, increased urine excretion is the result of
A) increased aldosterone production.
B) increased blood pressure.
C) inhibited secretion of antidiuretic hormone (ADH).
D) increased reabsorption of water in the proximal tubule.
E) the osmoregulator cells of the brain increasing their activity.

C)

The reason that the steroid hormone aldosterone affects only a small number of cells in the body is that
A) only its target cells get exposed to aldosterone.
B) only its target cells contain aldosterone receptors.
C) it is unable to enter nontarget cells.
D) nontarget cells destroy aldosterone before it can produce any effect.
E) nontarget cells convert aldosterone to a hormone to which they do respond.

B)

Different body cells can respond differently to the same peptide hormones because
A) different target cells have different sets of genes.
B) each cell converts that hormone to a different metabolite.
C) a target cell's response is determined by the components of its signal transduction pathways.
D) the circulatory system regulates responses to hormones by routing the hormones to specific targets.
E) the hormone is chemically altered in different ways as it travels through the circulatory system.

C)

Portal blood vessels connect two capillary beds found in the
A) hypothalamus and thalamus.
B) anterior pituitary and posterior pituitary.
C) hypothalamus and anterior pituitary.
D) posterior pituitary and thyroid gland.
E) anterior pituitary and adrenal gland.

C)

In a lactating mammal, the two hormones that promote milk synthesis and milk release, respectively, are
A) prolactin and calcitonin.
B) prolactin and oxytocin.
C) follicle-stimulating hormone and luteinizing hormone.
D) luteinizing hormone and oxytocin.
E) prolactin and luteinizing hormone.

B)

Prolactin stimulates mammary gland growth and development in mammals and regulates salt and water balance in freshwater fish. Many scientists think that this wide range of functions indicates that prolactin
A) is a nonspecific hormone.
B) has a unique mechanism for eliciting its effects.
C) is an evolutionarily conserved hormone.
D) is derived from two separate sources.
E) interacts with many different receptor molecules.

C)

The body's reaction to PTH (parathyroid hormone), a reduction in plasma levels of calcium, can be opposed by
A) thyroxine.
B) epinephrine.
C) growth hormone.
D) calcitonin.
E) glucagon.

D)

The autonomic nervous system includes an endocrine gland known as the
A) ovary.
B) adrenal medulla.
C) adrenal cortex.
D) testis.
E) thyroid.

B)

An advantage of asexual reproduction is that
A) asexual reproduction allows the species to endure long periods of unstable environmental conditions.
B) asexual reproduction enhances genetic variability in the species.
C) asexual reproduction enables the species to rapidly colonize habitats that are favorable to that species.
D) asexual reproduction produces offspring that respond effectively to new pathogens.
E) asexual reproduction allows a species to easily rid itself of harmful mutations

C)

Sexual reproduction patterns include the example of
A) fragmentation.
B) budding.
C) hermaphroditism.
D) parthenogenesis.
E) fission.

C)

Sexual reproduction
A) allows animals to conserve resources and reproduce only during optimal conditions.
B) can produce diverse phenotypes that may enhance survival of a population in a changing environment.
C) yields more numerous offspring more rapidly than is possible with asexual reproduction.
D) enables males and females to remain isolated from each other while rapidly colonizing habitats.
E) guarantees that both parents will provide care for each offspring.

B)

Evidence that parthenogenic whiptail lizards are derived from sexually reproducing ancestors includes
A) the requirement for male-like behaviors in some females before their partners will ovulate.
B) the development and then regression of testes prior to sexual maturation.
C) the observation that all of the offspring are haploid.
D) dependence on favorable weather conditions for ovulation to occur.
E) the persistence of a vestigial penis among some of the females.

A)

Internal and external fertilization both
A) produce zygotes.
B) occur only among invertebrates.
C) occur only among terrestrial animals.
D) depend on the use of intromittent copulatory organs.
E) occur only among birds.

A)

An oocyte released from a human ovary enters the oviduct as a result of
A) the beating action of the flagellum on the oocyte.
B) the force of the follicular ejection directing the oocyte into the oviduct.
C) the wavelike beating of cilia lining the oviduct.
D) movement of the oocyte through the pulsating uterus into the oviduct.
E) peristaltic contraction of ovarian muscles.

C)

In humans, the follicular cells that remain behind in the ovary following ovulation become
A) the ovarian endometrium that is shed at the time of the menses.
B) a steroid-hormone synthesizing structure called the corpus luteum.
C) the thickened portion of the uterine wall.
D) swept into the fallopian tube.
E) the placenta, which secretes cervical mucus.

B)

Testosterone is synthesized primarily by the
A) sperm cells.
B) hypothalamus.
C) Leydig cells.
D) anterior pituitary gland.
E) seminiferous tubules.

C)

Human sperm cells first arise in the
A) prostate gland.
B) vas deferens.
C) seminiferous tubules.
D) epididymis.
E) Sertoli cells.

C)

At the time of fertilization, the complete maturation of each oogonium has resulted in
A) one secondary oocyte.
B) two primary oocytes.
C) four secondary oocytes.
D) four primary oocytes.
E) four zygotes.

A)

In correct chronological order, the three phases of the human ovarian cycle are
A) menstrual → ovulation → luteal.
B) follicular → luteal → secretory.
C) menstrual → proliferative → secretory.
D) follicular → ovulation → luteal.
E) proliferative → luteal → ovulation.

D)

Ovulation is the follicular response to a burst of secretion of
A) LH.
B) progesterone.
C) inhibin.
D) prolactin.
E) estradiol.

A)

The hormone progesterone is produced
A) in the pituitary and acts directly on the ovary.
B) in the uterus and acts directly on the pituitary.
C) in the ovary and acts directly on the uterus.
D) in the pituitary and acts directly on the uterus.
E) in the uterus and acts directly on the pituitary.

C)

A reliable "marker" that a pregnancy has initiated is
A) progesterone.
B) estrogen.
C) follicle-stimulating hormone.
D) chorionic gonadotropin.
E) hypothalamic-releasing hormones.

D)

As an embryo develops, new cells are produced as the result of
A) differentiation.
B) preformation.
C) cell division.
D) morphogenesis.
E) epigenesis.

C)

During fertilization, the acrosomal contents
A) block polyspermy.
B) help propel more sperm toward the egg.
C) digest the protective jelly coat on the surface of the egg.
D) nourish the mitochondria of the sperm.
E) trigger the completion of meiosis by the sperm.

C)

From earliest to latest, the overall sequence of early development proceeds in which of the following sequences?
A) first cell division → synthesis of embryo's DNA begins → acrosomal reaction → cortical reaction
B) cortical reaction → synthesis of embryo's DNA begins → acrosomal reaction → first cell division
C) cortical reaction → acrosomal reaction → first cell division → synthesis of embryo's DNA begins
D) first cell division → synthesis of embryo's DNA begins → acrosomal reaction → cortical reaction
E) acrosomal reaction → cortical reaction → synthesis of embryo's DNA begins → first cell division

E)

Fertilization normally
A) reinstates diploidy.
B) follows gastrulation.
C) is required for parthenogenesis.
D) merges two diploid cells into one haploid cell.
E) precedes ovulation.

A)

As cleavage continues during frog development, the size of the blastomeres
A) increases as the number of the blastomeres decreases.
B) increases as the number of the blastomeres increases.
C) decreases as the number of the blastomeres increases.
D) decreases as the number of the blastomeres decreases.
E) increases as the number of the blastomeres stays the same.

C)

The vegetal pole of the zygote differs from the animal pole in that
A) the vegetal pole has a higher concentration of yolk.
B) the blastomeres originate only in the vegetal pole.
C) the posterior end of the embryo forms at the vegetal pole.
D) the vegetal pole cells undergo mitosis but not cytokinesis.
E) the polar bodies bud from this region.

A)

At the time of implantation, the human embryo is called a
A) blastocyst.
B) gastrula.
C) fetus.
D) somite.
E) zygote.

A)

Changes in the shape of a cell usually involve a reorganization of the
A) nucleus.
B) cytoskeleton.
C) extracellular matrix.
D) transport proteins.
E) nucleolus.

B)

Most of the organelles in a neuron are located in the
A) dendritic region.
B) axon hillock.
C) axon.
D) cell body.
E) axon terminals.

D)

In the communication between a motor neuron and a skeletal muscle,
A) the motor neuron is considered the presynaptic cell and the skeletal muscle is the postsynaptic cell.
B) the motor neuron is considered the postsynaptic cell and the skeletal muscle is the presynaptic cell.
C) action potentials are possible on the motor neuron but not the skeletal muscle.
D) action potentials are possible on the skeletal muscle but not the motor neuron.
E) the motor neuron fires action potentials but the skeletal muscle is not electrochemically excitable.

A)

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
A) the depolarization of the neuron.
B) the hyperpolarization of the neuron.
C) the replacement of potassium ions with sodium ions.
D) the replacement of potassium ions with calcium ions.
E) the neuron switching on its sodium-potassium pump to restore the initial conditions.

B)

The operation of the sodium-potassium "pump" moves
A) sodium and potassium ions into the cell.
B) sodium and potassium ions out of the cell.
C) sodium ions into the cell and potassium ions out of the cell.
D) sodium ions out of the cell and potassium ions into the cell.
E) sodium and potassium ions into the mitochondria.

D)

The "threshold" potential of a membrane
A) is the point of separation from a living to a dead neuron.
B) is the lowest frequency of action potentials a neuron can produce.
C) is the minimum hyperpolarization needed to prevent the occurrence of action potentials.
D) is the minimum depolarization needed to operate the voltage-gated sodium and potassium channels.
E) is the peak amount of depolarization seen in an action potential.

D)

Action potentials move along axons
A) more slowly in axons of large than in small diameter.
B) by the direct action of acetylcholine on the axonal membrane.
C) by activating the sodium-potassium "pump" at each point along the axonal membrane.
D) more rapidly in myelinated than in non-myelinated axons.
E) by reversing the concentration gradients for sodium and potassium ions.

D)

Saltatory conduction is a term applied to
A) conduction of impulses across electrical synapses.
B) an action potential that skips the axon hillock in moving from the dendritic region to the axon terminal.
C) rapid movement of an action potential reverberating back and forth along a neuron.
D) jumping from one neuron to an adjacent neuron.
E) jumping from one node of Ranvier to the next in a myelinated neuron.

E)

The surface on a neuron that discharges the contents of synaptic vesicles is the
A) dendrite.
B) axon hillock.
C) node of Ranvier.
D) postsynaptic membrane.
E) presynaptic membrane.

E)

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
A) a voltage-gated sodium channel.
B) a voltage-gated potassium channel.
C) a ligand-gated sodium channel.
D) a second-messenger-gated sodium channel.
E) a chemical that inhibits action potentials.

C)

An inhibitory postsynaptic potential (IPSP) occurs in a membrane made more permeable to
A) potassium ions.
B) sodium ions.
C) calcium ions.
D) ATP.
E) all neurotransmitter molecules.

A)

The following steps refer to various stages in transmission at a chemical synapse.

1. Neurotransmitter binds with receptors associated with the postsynaptic membrane.
2. Calcium ions rush into neuron's cytoplasm.
3. An action potential depolarizes the membrane of the axon terminal.
4. The ligand-gated ion channels open.
5. The synaptic vesicles release neurotransmitter into the synaptic cleft.

Which sequence of events is correct?

A) 1 → 2 → 3 → 4 → 5
B) 2 → 3 → 5 → 4 → 1
C) 3 → 2 → 5 → 1 → 4
D) 4 → 3 → 1 → 2 → 5
E) 5 → 1 → 2 → 4 → 3

C)

The activity of acetylcholine in a synapse is terminated by
A) its active transport across the presynaptic membrane.
B) its diffusion across the presynaptic membrane.
C) its active transport across the postsynaptic membrane.
D) its diffusion across the postsynaptic membrane.
E) its degradation by a hydrolytic enzyme on the postsynaptic membrane.

E)

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
A) temporal summation.
B) spatial summation.
C) tetanus.
D) the refractory state.
E) an action potential with an abnormally high peak of depolarization.

B)

The central nervous system is lacking in animals that have
A) a complete gut.
B) bilateral symmetry.
C) radial symmetry.
D) a closed circulatory system.
E) excitable membranes.

B)

The divisions of the nervous system that have antagonistic, or opposing, actions are
A) motor and sensory systems.
B) sympathetic and parasympathetic systems.
C) presynaptic and postsynaptic membranes.
D) forebrain and hindbrain.
E) central nervous system and peripheral nervous system.

B)

The activation of the parasympathetic branch of the autonomic nervous system is associated with
A) resting and digesting.
B) release of epinephrine into the blood.
C) increased metabolic rate.
D) fight-or-flight responses.
E) intensive aerobic exercise.

A)

The system that modulates excitation and inhibition of smooth and cardiac muscles of the digestive, cardiovascular, and excretory systems is the
A) central nervous system.
B) peripheral nervous system.
C) autonomic nervous system.
D) parasympathetic nervous system.
E) sympathetic nervous system.

C)

Hormones that are secreted by the posterior pituitary gland are made in the
A) cerebrum.
B) cerebellum.
C) thalamus.
D) hypothalamus.
E) medulla oblongata.

D)

The coordination of groups of skeletal muscles is driven by activity in the
A) cerebrum.
B) cerebellum.
C) thalamus.
D) hypothalamus.
E) medulla oblongata.

B)

Wernicke's and Broca's regions of the brain affect
A) olfaction.
B) vision.
C) speech.
D) memory.
E) hearing.

C)

The axons of rods and cones are found on
A) ganglion cells.
B) horizontal cells.
C) amacrine cells.
D) bipolar cells.
E) lateral cells

D)

What is the role of calcium in muscle contractions?
A) break cross-bridges by acting as a cofactor in the hydrolysis of ATP.
B) bind with troponin, changing its shape so that the myosin-binding sites on actin are exposed.
C) transmit action potentials from the motor neuron to the muscle fiber.
D) spread action potentials through the T tubules.
E) re-establish the polarization of the plasma membrane following an action potential.

B)

Which of the following is the correct sequence that describes the excitation and contraction of a skeletal muscle fiber?

1. Tropomyosin shifts and unblocks the cross-bridge binding sites.
2. Calcium is released and binds to the troponin complex.
3. Transverse tubules depolarize the sarcoplasmic reticulum.
4. The thin filaments are ratcheted across the thick filaments by the heads of the myosin molecules using energy from ATP.
5. An action potential in a motor neuron causes the axon to release acetylcholine, which depolarizes the muscle cell membrane.

A) 1 → 2 → 3 → 4 → 5

B) 2 → 1 → 3 → 5 → 4

C) 2 → 3 → 4 → 1 → 5

D) 5 → 3 → 1 → 2 → 4

E) 5 → 3 → 2 → 1 → 4

E)

The lumen of the transverse tubules of skeletal muscles contains
A) extracellular fluid.
B) cytosol.
C) actin.
D) myosin.
E) sarcomeres.

A)

In the life cycle of an angiosperm, which of the following stages is diploid?
A) megaspore
B) generative nucleus of a pollen grain
C) polar nuclei of the embryo sac
D) microsporocyte
E) both megaspore and polar nuclei

D)

Within the female gametophyte, three mitotic divisions of the megaspore produce
A) three antipodal cells, two polar nuclei, one egg, and two synergids.
B) the triple fusion nucleus.
C) three pollen grains.
D) two antipodal cells, two polar nuclei, two eggs, and two synergids.
E) a tube nucleus, a generative cell, and a sperm cell.

A)

Cells elongate in response to auxin. All of the following are part of the acid growth hypothesis except
A) Auxin stimulates proton pumps in cell membranes.
B) Lowered pH results in the breakage of cross-links between cellulose microfibrils.
C) The wall fabric becomes looser (more plastic).
D) Auxin-activated proton pumps stimulate cell division in meristems.
E) The turgor pressure of the cell exceeds the restraining pressure of the loosened cell wall, and the cell takes up water and elongates.

D)

In general, which of the following is not a plant response to herbivores?
A) domestication, so that humans can protect the plant
B) attracting predatory animals, such as parasitoid wasps
C) chemical defenses, such as toxic compounds
D) physical defenses, such as thorns
E) production of volatile molecules

A)

The pH of the gastric juice is about 2 due to the formation of HCL. Where does this formation of HCL occur?
A. In the chief cells of the stomach
B. In the parietal cells of the stomach
C. In the transformation of pepsinogen to pepsin
D. In the secretions of the esophagus
E. In the lumen of the stomach

E)

An anthropologist discovers fossilized animal remains that give strong evidence that the organism had a large, well-formed, most likely 4-chambered heart, with no connection between the right and left sides. Which of the following could most reasonably behypothesized from this observation?
A) that the animal and its relatives had evolved from birds
B) that the animal had a high energy requirement and was endothermic
C) that the animal was most closely related to reptiles such as alligators and crocodiles
D) that the animal was a kind of invertebrate
E) that the species had little to no need to regulate blood pressure

B)

Which of the following differentiates T cells and B cells?
A) T cells but not B cells are stimulated to increase the rate of their cell cycles
B) Only B cells are produced from stem cells of the bone marrow
C) T cells but not B cells can directly attack and destroy invading pathogens
D) T cells but not B cells have surface markers
E) Only B cells take part in cell-mediated immunity

C)

What would account for increased urine production as a result of drinking alcoholic beverages?
A) increased aldosterone production
B) increased blood pressure
C) decreased amount of antidiuretic hormone (ADH)
D) increased reabsorption of water in the proximal tubule
E) the osmoregulator cells of the brain increasing their activit

C)

Which of the following glands is controlled directly by the hypothalamus or central nervous system but not the anterior pituitary?
A) ovary
B) adrenal medulla
C) adrenal cortex
D) testis
E) thyroid

B)

In response to stress, the adrenal gland promotes the synthesis of glucose from noncarbohydrate substrates via the action of the steroid hormone
A) glucagon.
B) glucocorticoids.
C) epinephrine.
D) thyroxine.
E) ACTH.

B)

Which statement is false concerning reproduction in invertebrate animals?
A) Separate sexes are not observed among any invertebrates.
B) Some have both sexes within one individual organism.
C) Some utilize external fertilization.
D) Some utilize internal fertilization.
E) None of the invertebrates have structures that store sperm.

E)

The general functions of the nervous system include which of the following?
I. integration
II. motor output
III. sensory input

a. I only
b. II only
c. III only
d. I and II only
e. I, II, and III

E)

If a stimulus is to be perceived by the nervous system, which part of the sensory pathway must occur first?

A) integration

B) transmission

C) transduction

D) reception

E) amplification

D)

Which of the major senses responds by means of a very large gene family?

A) smell
B) equilibrium
C) taste
D) vision
E) hearing

A)

Which of the following does not form part of the thin filaments of a muscle cell?

A) actin
B) myosin
C) calcium-binding site
D) troponin
E) trpomyosin

B)

What are animals with hydrostatic skeletons able to do that animals with exoskeletons or internal skeletons cannot do?

A) elongate

B) crawl

C) live in aquatic environments

D) grow without replacing their skeleton

E) A, B, and D

A)

In plant roots, the Casparian strip is correctly described by which of the following?
A) It aids in the uptake of nutrients.
B) It provides energy for the active transport of minerals into the stele from the cortex.
C) It ensures that all minerals are absorbed from the soil in equal amounts.
D) It ensures that all water and dissolved substances must pass through a cell membrane before entering the stele.
E) It provides increased surface area for the absorption of mineral nutrients.

D)

What is the main force by which most of the water within xylem vessels moves toward the top of a tree?
A) active transport of ions into the stele
B) atmospheric pressure on roots
C) evaporation of water through stoma
D) the force of root pressure
E) osmosis in the root

C)

What soil(s) is(are) the most fertile?

A) Loam only

B) Silt only

C) Humus only

D) A mix of humus and loam

E) Clay only

D)

Mutualistic associations between roots and soil fungi are called ___?

A) root hair enhancement
B) nitrogen fixation
C) parasitism
D) mycorrhizae
E) Rhizobium infection

D)

At the conclusion of meiosis in plants, the end products are always four haploid
A) spores.
B) eggs.
C) sperm.
D) seeds.
E) gametes.

A)

Which of the following is the correct sequence during the alternation of generations life cycle in a flowering plant?

A) sporophyte → meiosis →spores → mitosis → gametophyte → gametes → fertilization → diploid zygote
B) sporophyte → mitosis → gametophyte → meiosis → sporophyte
C) haploid gametophyte → gametes → meiosis → fertilization → diploid sporophyte
D) sporophyte → spores → meiosis → gametophyte → gametes
E) haploid sporophyte → spores → fertilization → diploid gametophyte

A)

Microsporangia in flowering plants are located in the
A) stamen.
B) carpel.
C) petals.
D) sepals.
E) receptacle.

A)

A perfect flower is fertile, but may be either complete or incomplete. Which of the following correctly describes a perfect flower?
A) It has no sepals.
B) It has fused carpels.
C) It is on a dioecious plant.
D) It has no endosperm.
E) It has both stamens and carpels.

E)

Meiosis occurs within all of the following flower parts except the
A) ovule.
B) style.
C) megasporangium.
D) anther.
E) ovary.

B)

The embryo of a grass seed is enclosed by two protective sheaths, a(n) ________, which covers the young shoot, and a(n) ________, which covers the young root.
A) cotyledon; radicle
B) hypocotyl; epicotyl
C) coleoptile; coleorhiza
D) scutellum; coleoptile
E) epicotyl; radicle

C)

What is the first organ to emerge from a germinating educate seed?

A) radicle
B) plumule
C) shoot
D) hypocotyl
E) epicotyl

A)

The apical bud of a pine tree inhibits the growth of lateral buds through the production of
A) abscisic acid.
B) ethylene.
C) cytokinin.
D) gibberellin.
E) auxin.

E)

One effect of gibberellins is to stimulate barley seeds to produce
A) RuBP carboxylase.
B) lipids.
C) abscisic acid.
D) starch.
E) amylase.

E)

In angiosperm seed development what does the terminal cell become?

A) proembryo
B) cotyledons
C) suspensors
D) apical meristem
E) endosprem

A)

In marine sponges, intracellular digestion of peptides is usually immediately preceded by _____.

A) hydrolysis
B) phagocytosis
C) absorption
D) secretion
E) exocytosis

B)

The active ingredient orlistat acts to decrease the amount of fat that is absorbed by attaching to enzymes that digest fat. Which of the following are potential targets of orlistat?

A) salivary amylase
B) pepsidase
C) pancreatic lipase
D) secretin
E) gastrin

C)

If you place a small piece of a cracker on your tongue, what would you expect to happen?

A) The vitamins in the cracker are immediately absorbed.
B) Salivary amylase degrades the starch from the cracker into glucose.
C) The proteins in the cracker begin to be digested.
D) The flavor becomes less noticeable because the sugars are digested.

B)

Over-the-counter medications for acid reflux or heartburn block the production of stomach acid. Which of the following cells are directly affected by this medication?

A) goblet cells
B) chief cells
C) parietal cells
D) smooth muscle cells
E) cardiac muscle cells

C)

Which of the following develops the greatest pressure on the blood in the mammalian aorta?
A) systole of the left atrium
B) diastole of the right ventricle
C) systole of the left ventricle
D) diastole of the right atrium
E) diastole of the left atrium

C)

An anthropologist discovers the fossilized heart of an extinct animal. The evidence indicates that the organism's heart was large, well-formed, and had four chambers, with no connection between the right and left sides. A reasonable conclusion supported by these observations is that the
A) animal had evolved from birds.
B) animal was endothermic and had a high metabolic rate.
C) animal was most closely related to alligators and crocodiles.
D) animal was likely an invertebrate animal.
E) species had little to no need to regulate blood pressure.

B)

To adjust blood pressure independently in the capillaries of the gas-exchange surface and in the capillaries of the general body circulation, an organism would need a(n)
A) open circulatory system.
B) hemocoel.
C) lymphatic system.
D) two-chambered heart.
E) four-chambered heart.

E)

A patient with a blood pressure of 120/75, a pulse rate of 40 beats/minute, a stroke volume of 70 mL/beat, and a respiratory rate of 25 breaths/minute will have a cardiac output of
A) 500 mL/minute.
B) 1,000 mL/minute.
C) 1,750 mL/minute.
D) 2,800 mL/minute.
E) 4,900 mL/minute.

E)

If a molecule of CO2 released into the blood in your left toe is exhaled from your nose, it must pass through all of the following except
A) the pulmonary vein.
B) an alveolus.
C) the trachea.
D) the right atrium.
E) the pulmonary artery.

A)

Cyanide poisons mitochondria by blocking the final step in the electron transport chain. Human red blood cells placed in an isotonic solution containing cyanide are likely to
A) retain the normal cell shape, but the mitochondria will be poisoned.
B) lyse as the cyanide concentration increases inside the cell.
C) switch to anaerobic metabolism.
D) become unable to carry oxygen.
E) be unaffected.

E)

Engulfing-phagocytic cells of innate immunity include all of the following except
A) neutrophils.
B) macrophages.
C) dendritic cells.
D) natural killer cells.

D)

Mammals have Toll-like receptors (TLRs) that can recognize a kind of macromolecule that is absent from vertebrates but present in/on certain groups of pathogens, including viral
A) lipopolysaccharides.
B) double-stranded DNA.
C) double-stranded RNA.
D) glycoproteins.
E) phospholipids.

C)

Clonal selection is an explanation for how
A) a single type of stem cell can produce both red blood cells and white blood cells.
B) V, J, and C gene segments are rearranged.
C) an antigen can provoke production of high levels of specific antibodies.
D) HIV can disrupt the immune system.
E) macrophages can recognize specific T cells and B cells.

C)

Yearly vaccination of humans for influenza viruses is necessary because
A) of an increase in immunodeficiency diseases.
B) flu can generate anaphylactic shock.
C) surviving the flu one year exhausts the immune system to nonresponsiveness the second year.
D) rapid mutation in flu viruses alters the surface proteins in infected host cells.
E) flu leads to autoimmune disorders.

D)

Arrange these components of the mammalian immune system as it first responds to a pathogen in the correct sequence.
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.
A) I → III → II → IV → V
B) III → II → I → V → IV
C) II → I → IV → III → V
D) IV → II → III → I → V
E) III → IV → II → I → V

E)

If a patient is mission B and T cells, what would be absent from the immune system responses?

A) lysozymes
B) interferons
C) defense against bacteria
D) memory
E) cytokines

D)

Sharks live in seawater. Their tissues are isotonic to seawater, but their concentrations of sodium ions, potassium ions, and chloride ions in cells and extracellular fluids are similar to those of freshwater fishes. How is that possible?

A) Urea and trimethylamine oxide contribute to intra- and extracellular osmolarity in shark tissues.
B) Metabolic intermediates of sharks tie up intracellular chloride and potassium ions.
C) Their blood is hypotonic to their tissues.
D) They excrete large quantities of electrolytes.

A)

Through studies of insect Malpighian tubules, researchers found that K+ accumulated on the inner face of the tubule, against its concentration gradient. What can you infer about the mechanism of transport?

A) Potassium transport is a passive process.
B) Movement of potassium into the lumen of the Malpighian tubules is an energy-requiring process.
C) Potassium moves out of the tubules at a faster rate than it moves into the lumen of the tubules.
D) Sodium ions will follow potassium ions.

B)

Materials are returned to the blood from the filtrate by which of the following processes?

A) filtration
B) reabsorption
C) secretion
D) excretion
E) hydrolysis

B)

Choose a pair that correctly associates the mechanism for osmoregulation or nitrogen removal with the appropriate animal.

A) metanephridium — flatworm
B) Malpighian tubule — frog
C) flame bulb — snake
D) exchange across the body surface — marine invertebrate
E) protonephridium- ringworm

D)

The loop of Henle dips into the renal cortex. This is an important feature of osmoregulation in terrestrial vertebrates because _____.

A) absorptive processes taking place in the loop of Henle are hormonally regulated
B) differential permeabilities of ascending and descending limbs of the loop of Henle are important in establishing an osmotic gradient
C) the loop of Henle plays an important role in detoxification
D) additional filtration takes place along the loop of Henle

B)

You are dissecting a fish in your biology laboratory section. Your teaching assistant points out a long oval structure and tells you it is an endocrine gland. Which of the following would you then know is a true statement about this structure?

A) It secretes a product that is released through a series of ducts.
B) The gland's product will only interact with receptors on the cell membrane.
C) The gland's product is lipid soluble.
D) The gland produces and secretes its product into the blood.

D)

In experiments where researchers suspect that a hormone may be responsible for a certain physiological effect, they may cut the neurons leading to the organ where the effect being studied occurs. What is the purpose of cutting these neurons?

A) to make sure that the effect is not occurring through actions in the nervous system
B) to make sure that the organ being affected cannot function unless the researchers stimulate it with an external electrical probe
C) to impair the normal functions of the organ so that the hormonal effect can be more easily studied
D) to numb the organ so that it can be probed without inducing pain in the lab animal

A)

Hormone X activates the cAMP second messenger system in its target cells. The greatest response by a cell would come from _____.

A) applying a molecule of hormone X to the extracellular fluid surrounding the cell
B) injecting a molecule of hormone X into the cytoplasm of the cell
C) applying a molecule of cAMP to the extracellular fluid surrounding the cell
D) injecting a molecule of activated, cAMP-dependent protein kinase into the cytoplasm of the cell

A)

Oxytocin and antidiuretic hormone (ADH) are synthesized in the _____ and stored in the ____.

A) hypothalamus; posterior pituitary
B) anterior pituitary; kidneys
C) anterior pituitary; thyroid
D) posterior pituitary; anterior pituitary
E) adrenal cortex; adrenal medulla

A)

which hormone exerts antagonistic action to PTH (parathyroid hormone)?

A) thyroxine
B) epinephrine
C) growth hormone
D) calcitonin
E) glucagon

D)

Glucocorticoids do which of the following?

A) promote the immune response
B) promote the release of fatty acids
C) increase blood glucose levels
D) increase insulin production
E) promote reabsorption of Na+

C)

If the adrenal cortex were removed, which group of hormones would be most affected?

A) peptide
B) amino-acid derived
C) tropic
D) paracrine
E) steroid

E)

Portal blood vessels connect two capillary beds found in the _____.

A) hypothalamus and thalamus
B) anterior pituitary and posterior pituitary
C) hypothalamus and anterior pituitary
D) posterior pituitary and thyroid gland
E) thalamus and anterior pituitary

C)

Tadpoles must undergo a major metamorphosis to become frogs. This change includes reabsorption of the tail, growth of limbs, calcification of the skeleton, increase in rhodopsin in the eye, development of lungs, change in hemoglobin structure, and reformation of the gut from the long gut of an herbivore to the short gut of a carnivore. Amazingly, all of these changes are induced by thyroxine. What is the most likely explanation for such a wide array of effects of thyroxine?

A) There are many different forms of thyroxine, each specific to a different tissue.
B) Different tissues have thyroxine receptors that activate different signal transduction pathways.
C) Some tissues have membrane receptors for thyroxine, while other tissues have thyroxine receptors within the nucleus.
D) Different releasing hormones release thyroxine to different tissues.

B)

A blood vessel has the following characteristics: outer layer of connective tissue, a thick layer of smooth muscle with elastic fibers, no valves. It is which of the following?
A) a vein
B) a venule
C) an artery
D) a capillary
E) a portal vessel

C)

What type of immunity is associated with breastfeeding?

A) passive immunity
B) active immunity
C) cell-mediated immunity
D) innate immunity
E) adaptive immunity

A)