unit 5 mastering biology

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Unlike an earthworm’s metanephridia, a mammalian nephron

functions in both osmoregulation and excretion.
is intimately associated with a capillary network.
forms urine by changing fluid composition inside a tubule.
has a transport epithelium.
receives filtrate from blood instead of coelomic fluid.

receives filtrate from blood instead of coelomic fluid.

Which process in the nephron is least selective?

secretion
salt pumping by the loop of Henle
reabsorption
active transport
filtration

filtration

which of the following animals generally has the lowest volume of urine production?

a shark inhabiting freshwater Lake Nicaragua
a marine bony fish
a freshwater bony fish
a vampire bat
a salmon in fresh water

a marine bony fish

The high osmolarity of the renal medulla is maintained by all of the following except

diffusion of salt from the descending limb of the loop of Henle.
the spatial arrangement of juxtamedullary nephrons.
diffusion of salt from the thin segment of the ascending limb of the loop of Henle.
active transport of salt from the upper region of the ascending limb.
diffusion of urea from the collecting duct.

diffusion of salt from the descending limb of the loop of Henle.

Natural selection should favor the highest proportion of juxtamedullary nephrons in which of the following species?

a beaver
a river otter
a mouse species living in a desert
a mouse species living in a temperate broadleaf forest
a mouse species living in a tropical rain forest

a mouse species living in a desert

African lungfish, which are often found in small stagnant pools of fresh water, produce urea as a nitrogenous waste. What is the advantage of this adaptation?

The highly toxic urea makes the pool uninhabitable to potential competitors.
Urea takes less energy to synthesize than ammonia.
Urea forms an insoluble precipitate.
Urea makes lungfish tissue hypoosmotic to the pool.
Small stagnant pools do not provide enough water to dilute the toxic ammonia.

Small stagnant pools do not provide enough water to dilute the toxic ammonia.

Which of the following is not an accurate statement?

Hormones of the same chemical class usually have the same function.
Hormones are chemical messengers that travel to target cells through the circulatory system.
Hormones are often regulated through feedback loops.
Hormones are secreted by specialized cells usually located in endocrine glands.
Hormones often regulate homeostasis through antagonistic functions.

Hormones of the same chemical class usually have the same function.

An example of antagonistic hormones controlling homeostasis is

epinephrine and norepinephrine in fight-or-flight responses.
progestins and estrogens in sexual differentiation.
oxytocin and prolactin in milk production.
thyroxine and parathyroid hormone in calcium balance.
insulin and glucagon in glucose metabolism.

insulin and glucagon in glucose metabolism.

Growth factors are local regulators that

bind to cell-surface receptors and stimulate growth and development of target cells.
are modified fatty acids that stimulate bone and cartilage growth.
are produced by the anterior pituitary.
convey messages between nerve cells.
are found on the surface of cancer cells and stimulate abnormal cell division.

bind to cell-surface receptors and stimulate growth and development of target cells.

Which hormone is incorrectly paired with its action?

ACTH-stimulates the release of glucocorticoids by the adrenal cortex
melatonin-affects biological rhythms, seasonal reproduction
insulin-stimulates glycogen breakdown in the liver
oxytocin-stimulates uterine contractions during childbirth
thyroxine-stimulates metabolic processes

insulin-stimulates glycogen breakdown in the liver

Steroid and peptide hormones typically have in common

the location of their receptors.
their requirement for travel through the bloodstream.
their reliance on signal transduction in the cell.
their solubility in cell membranes.
the building blocks from which they are synthesized.

their requirement for travel through the bloodstream.

Which of the following is the most likely explanation for hypothyroidism in a patient whose iodine level is normal?

a decrease in the thyroid secretion of calcitonin
hypersecretion of TSH
hypersecretion of MSH
hyposecretion of TSH
greater production of T3 than of T4

hyposecretion of TSH

Shortly after ingesting a big plate of carbohydrate-rich pasta, you measure your blood’s hormone levels. What results would you expect, compared to before the meal?

low insulin, low glucagon
high insulin, low glucagon
low insulin, high glucagon
high insulin, high glucagon
low insulin, no change in glucagon

high insulin, low glucagon

The relationship between the insect hormones ecdysteroid and PTTH is an example of

competitive inhibition of a hormone receptor.
how peptide-derived hormones have more widespread effects than steroid hormones.
an interaction of the endocrine and nervous systems.
homeostasis achieved by positive feedback.
homeostasis maintained by antagonistic hormones.

an interaction of the endocrine and nervous systems.

Which of the following characterizes parthenogenesis?

Specialized groups of cells grow into new individuals.
Both mates have male and female reproductive organs.
An egg develops without being fertilized.
An organism is first a male and then a female.
An individual may change its sex during its lifetime.

An egg develops without being fertilized.

In male mammals, excretory and reproductive systems share

the urethra.
the testes.
the vas deferens.
the seminal vesicle.
the prostate.

the urethra

Which of the following is not properly paired?

vas deferens-oviduct
seminiferous tubule-cervix
scrotum-labia majora
testosterone-estradiol
Sertoli cells-follicle cells

seminiferous tubule-cervix

Peaks of LH and FSH production occur during

the end of the luteal phase of the ovarian cycle.
the menstrual flow phase of the uterine cycle.
the beginning of the follicular phase of the ovarian cycle.
the secretory phase of the menstrual cycle.
the period just before ovulation.

the period just before ovulation.

During human gestation, rudiments of all organs develop

in the second trimester.
while the embryo is in the oviduct.
in the third trimester.
during the blastocyst stage.
in the first trimester.

in the first trimester.

Which of the following is a true statement?

The endometrial lining is shed in menstrual cycles but reabsorbed in estrous cycles.
All mammals have menstrual cycles.
Ovulation occurs before the endometrium thickens in estrous cycles.
Estrous cycles are not controlled by hormones.
Estrous cycles are more frequent than menstrual cycles.

The endometrial lining is shed in menstrual cycles but reabsorbed in estrous cycles.

For which of the following is the number the same in spermatogenesis and oogenesis?

gametes produced in a given time period
functional gametes produced by meiosis
interruptions in meiotic divisions
different cell types produced by meiosis
meiotic divisions required to produce each gamete

meiotic divisions required to produce each gamete

Which statement about human reproduction is false?

An oocyte completes meiosis after a sperm penetrates it.
Spermatogenesis and oogenesis require different temperatures.
Effective hormonal contraceptives are currently available only for females.
Fertilization occurs in the oviduct.
The earliest stages of spermatogenesis occur closest to the lumen of the seminiferous tubules.

The earliest stages of spermatogenesis occur closest to the lumen of the seminiferous tubules.

The cortical reaction of sea urchin eggs functions directly in

the generation of an electrical impulse by the egg.
the production of a fast block to polyspermy.
the release of hydrolytic enzymes from the sperm.
the formation of a fertilization envelope.
the fusion of egg and sperm nuclei.

the formation of a fertilization envelope.

Which of the following is common to the development of both birds and mammals?

epiblast and hypoblast
trophoblast
yolk plug
holoblastic cleavage
gray crescent

epiblast and hypoblast

The archenteron develops into

the mesoderm.
the blastocoel.
the lumen of the digestive tract.
the endoderm.
the placenta.

the lumen of the digestive tract.

What structural adaptation in chickens allows them to lay their eggs in arid environments rather than in water?

development of the brain from ectoderm
cleavage
gastrulation
extraembryonic membranes
yolk

extraembryonic membranes

In an egg cell treated with EDTA, a chemical that binds calcium and magnesium ions,

the fusion of sperm and egg nuclei would be blocked.
the acrosomal reaction would be blocked.
the fast block to polyspermy would not occur.
the fertilization envelope would not form.
the zygote would not contain maternal and paternal chromosomes.

the fertilization envelope would not form.

In humans, identical twins are possible because

early blastomeres can form a complete embryo if isolated.
cytoplasmic determinants are distributed unevenly in unfertilized eggs.
convergent extension occurs.
extraembryonic cells interact with the zygote nucleus.
the gray crescent divides the dorsal-ventral axis into new cells.

early blastomeres can form a complete embryo if isolated.

Cells transplanted from the neural tube of a frog embryo to the ventral part of another embryo develop into nervous system tissues. This result indicates that the transplanted cells were

mesenchymal.
determined.
apoptotic.
differentiated.
totipotent.

determined.

In an embryonic vertebrate, the apical ectodermal ridge (AER) is a thickened area at the tip of the bud. The cells of the AER secrete protein signals that promote limb-bud outgrowth, and removing the AER blocks growth of the limb along the proximal-distal axis. How would the forelimb of an embryo develop if the AER was removed early or late in limb development?

Early removal of the AER would prevent the formation of many distal structures, whereas late removal of the AER would prevent the formation of a few distal structures.
Early or late removal of the AER would have the same result: the embryo would not develop a forelimb.
Early removal of the AER would prevent the development of a forelimb, whereas late removal of the AER would not have any effect.

Early removal of the AER would prevent the formation of many distal structures, whereas late removal of the AER would prevent the formation of a few distal structures.

Select the correct statement about embryonic development in a frog.

Development from zygote to blastula involves mitotic division, cell movement, and cell growth.
The blastocoel of a developing frog embryo develops into the digestive tract.
The reorganization of cell layers during gastrulation allows the layers to interact with each other in new ways.

The reorganization of cell layers during gastrulation allows the layers to interact with each other in new ways.

The allantois stores nitrogenous wastes in a reptile egg. What is the function of the allantois in human development?

The allantois does not play any role in human development, because the placenta mediates the transfer of nitrogenous wastes from embryonic to maternal circulation.
The allantois helps form the umbilical cord in human development.
The allantois cushions the human embryo in a private "pond" during development.

The allantois helps form the umbilical cord in human development.

Identify the correct statement(s) about Spemann’s organizer.
Select all that apply.

Spemann’s organizer is the dorsal lip of the blastopore in frog gastrulation.
Spemann’s organizer initiates a chain of inductive interactions in frog development.
Spemann’s organizer is made up of totipotent cells.

Spemann’s organizer is the dorsal lip of the blastopore in frog gastrulation. Spemann’s organizer initiates a chain of inductive interactions in frog development.

In an embryonic vertebrate, the zone of polarizing activity (ZPA) is a block of tissue located on the posterior side of a limb bud. The ZPA provides information about the anterior-posterior axis of the limb. Cells nearest the ZPA form the most posterior of digits (like our little finger); cells farthest from the ZPA form the most anterior digits (like our thumb).

How would a vertebrate forelimb bud develop if it had two zones of polarizing activities, one on the posterior side and one on the anterior side of the bud?

The forelimb bud would develop into a hind limb.
The embryo wouldn’t develop a forelimb.
The forelimb bud would develop with extra digits, in a mirror image arrangement to the normal digits.

The forelimb bud would develop with extra digits, in a mirror image arrangement to the normal digits.

What happens when a resting neuron’s membrane depolarizes?

There is a net diffusion of Na+ out of the cell.
The equilibrium potential for K+ (E K) becomes more positive.
The neuron’s membrane voltage becomes more positive.
The cell’s inside is more negative than the outside.
The neuron is less likely to generate an action potential.

The neuron’s membrane voltage becomes more positive.

A common feature of action potentials is that they

cause the membrane to hyperpolarize and then depolarize.
move at the same speed along all axons.
are triggered by a depolarization that reaches the threshold.
require the diffusion of and through ligand-gated channels to propagate.
can undergo temporal and spatial summation.

are triggered by a depolarization that reaches the threshold.

Where are neurotransmitter receptors located?

synaptic vesicle membranes
the postsynaptic membrane
the nuclear membrane
the myelin sheath
the nodes of Ranvier

the postsynaptic membrane

Temporal summation always involves

inputs that are not simultaneous.
synapses at more than one site.
both inhibitory and excitatory inputs.
multiple inputs at a single synapse.
electrical synapses.

multiple inputs at a single synapse.

Why are action potentials usually conducted in one direction?

Voltage-gated channels for both Na+ and K+ open in only one direction.
The brief refractory period prevents reopening of voltage-gated Na+ channels.
Ions can flow along the axon in only one direction.
The axon hillock has a higher membrane potential than the terminals of the axon.
The nodes of Ranvier conduct potentials in one direction.

The brief refractory period prevents reopening of voltage-gated Na+ channels.

Which of the following is a direct result of depolarizing the presynaptic membrane of an axon terminal?

An EPSP or IPSP is generated in the postsynaptic cell.
The postsynaptic cell produces an action potential.
Ligand-gated channels open, allowing neurotransmitters to enter the synaptic cleft.
Synaptic vesicles fuse with the membrane.
Voltage-gated calcium channels in the membrane open.

Voltage-gated calcium channels in the membrane open.

Why is an action potential an all-or-none response to stimuli?

Because a typical neuron receives signals through multiple dendrites but transmits signals through a single axon
Because neurons contain gated ion channels that are either open or closed
Because voltage-gated ion channels open when membrane potential passes a particular level

Because voltage-gated ion channels open when membrane potential passes a particular level

What causes the falling phase of the action potential? Select the best answer.

The opening of voltage-gated sodium channels
Inactivation of voltage-gated sodium channels and the opening of voltage-gated potassium channels
The opening of voltage-gated potassium channels

Inactivation of voltage-gated sodium channels and the opening of voltage-gated potassium channels

If the membrane potential of a neuron decreases, the membrane potential _____.

remains unchanged.
becomes more negative.
becomes more positive.

becomes more positive.

The plasma membrane of a neuron has voltage-gated sodium and potassium channels. What is the effect of membrane depolarization on these channels?

Membrane depolarization opens sodium and potassium channels at the same time.
Membrane depolarization first opens sodium channels and then opens potassium channels.
Membrane depolarization opens sodium channels but closes potassium channels.

Membrane depolarization first opens sodium channels and then opens potassium channels.

Identify the correct statement(s) about the resting membrane potential of a cell.
Select all that apply.

Potassium (K+) and sodium (Na+) gradients are maintained by active transport in a resting mammalian neuron.
Neurons are the only cells that have a charge difference across their membranes.
Concentration gradients of potassium (K+) and sodium (Na+) across the plasma membrane represent potential energy.

Potassium (K+) and sodium (Na+) gradients are maintained by active transport in a resting mammalian neuron. Concentration gradients of potassium (K+) and sodium (Na+) across the plasma membrane represent potential energy.

Wakefulness is regulated by the reticular formation, which is present in the

spinal cord.
limbic system.
basal nuclei.
cerebral cortex.
brainstem.

brainstem.

Which of the following structures or regions is incorrectly paired with its function?

corpus callosum-communication between the left and right cerebral cortices
amygdala-emotional memory
limbic system-motor control of speech
medulla oblongata-homeostatic control
cerebellum-coordination of movement and balance

limbic system-motor control of speech

Patients with damage to Wernicke’s area have difficulty

coordinating limb movement.
generating speech.
experiencing emotion.
understanding language.
recognizing faces.

understanding language.

The cerebral cortex plays a major role in all of the following except

foot-tapping rhythm.
long-term memory.
circadian rhythm.
short-term memory.
breath holding.

circadian rhythm.

After suffering a stroke, a patient can see objects anywhere in front of him but pays attention only to objects in his right field of vision. When asked to describe these objects, he has difficulty judging their size and distance. What part of the brain was likely damaged by the stroke?

the corpus callosum
the left parietal lobe
the right frontal lobe
the left frontal lobe
the right parietal lobe

the right parietal lobe

Injury localized to the hypothalamus would most likely disrupt

executive functions, such as decision making.
short-term memory.
coordination during locomotion.
regulation of body temperature.
sorting of sensory information.

regulation of body temperature.

Identify the role(s) of glia in the vertebrate brain.
Select all that apply.

Glia release neurotransmitters.
Glia protect the nervous system from pathogens.
Glia guide neuron migration during development of the CNS

Glia release neurotransmitters. Glia protect the nervous system from pathogens. Glia guide neuron migration during development of the CNS

Which examples correctly illustrate the cooperation between the motor and nervous systems to maintain homeostasis in a vertebrate body?
Select all that apply.

A drop in body temperature leads to shivering and constriction of surface blood vessels.
In response to a sudden fright, the body responds by increasing heart rate, inhibiting digestion, and increasing blood glucose.
If you put your hand on a hot burner, a reflex pulls your hand back before you sense pain.

A drop in body temperature leads to shivering and constriction of surface blood vessels.

Which of these observations illustrate the developmental plasticity of the human nervous system?
Select all that apply.

When activity at a synapse correlates with the activity of other synapses, that synaptic connection is reinforced.
A person suffering from phantom limb pain following amputation may stop feeling pain after viewing a reflection of the remaining limb in a mirrored box.
The brain may ignore certain stimuli and actively process other stimuli.

When activity at a synapse correlates with the activity of other synapses, that synaptic connection is reinforced. A person suffering from phantom limb pain following amputation may stop feeling pain after viewing a reflection of the remaining limb in a mirrored box.

Identify the correct statement(s) about glial cells and their functions.
Select all that apply.

Oligodendrocytes act as stem cells, producing neurons and glia.
Schwann cells myelinate dendrites in the PNS.
Astrocytes induce the formation of the blood-brain barrier.

Astrocytes induce the formation of the blood-brain barrier.

Which of these observations illustrate regional specialization in the human nervous system?
Select all that apply.

Reading a printed word out loud and then thinking of a related word involves the visual cortex, Broca’s area, and the frontal and temporal lobes.
Sensory information may be processed in the occipital lobe or the temporal lobe.
When the activity of a synapse fails to correlate with that of other synapses, the synaptic connection may become weaker.

Reading a printed word out loud and then thinking of a related word involves the visual cortex, Broca’s area, and the frontal and temporal lobes. Sensory information may be processed in the occipital lobe or the temporal lobe.

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