Unit 3 Review: Biol 11B

Single-celled Paramecium live in pond water (a hypotonic environment relative to the cytosol). They have a structural feature, a contractile vacuole, which enables them to osmoregulate. If sucrose or saline was added to the pond water in different concentrations (in millimolars, mM), under which conditions would you expect the contractile vacuole to be most active?

0.0 mM sucrose

If an action potential lasts from the beginning of the rising phase to the point of maximal undershoot, what is the maximum frequency at which a neuron could fire action potentials? Assume that the neuron can fire only one action potential at a time and that the refractory period following the action potential is equal in length to the action potential.

220 events per second (2.3 msec+ 2.3 msec for refractory period = 4.6 so 1 event/4.6msec * 1000msec/sec)

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 presynaptic 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?

3-2-5-1-4

Which examples correctly illustrate the cooperation between the motor and nervous systems to maintain homeostasis in a vertebrate body?

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

Antidiuretic hormone (ADH) and the renin-angiotensin-aldosterone system (RAAS) work together in maintaining osmoregulatory homeostasis through which of the following ways?

ADH regulates the osmolarity of the blood by altering renal reabsorption of water, and the RAAS maintains the osmolarity of the blood by stimulating both Na+ and water reabsorption.

Vertebrates have two major communication and control systems: the endocrine system and the nervous system. Choose the correct statement describing the coordination of these systems.

Epinephrine functions as a hormone in the endocrine system and as a neurotransmitter in the nervous system.

Arrange in the correct sequence these components of the mammalian immune system as it first responds to a pathogen. I) Pathogen is destroyed. II) Lymphocytes secrete antibodies. III) Antigens from a pathogen bind to antigen receptors on lymphocytes. IV) Lymphocytes specific to antigens from a pathogen become numerous. V) Only memory cells remain.

III-IV-II-I-V

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 first opens sodium channels and then opens potassium channels.

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

The allantois helps form the umbilical cord in human development.

Which statement about human reproduction is false?

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

During mammalian labor and delivery, the contraction of uterine muscles is enhanced by oxytocin. This is an example of _____.

a hormone that is involved in a positive feedback loop

Which statement about human reproduction is correct?

a human oocyte only completes meiosis II after being penetrated by sperm

Acetylcholine released into the junction between a motor neuron and a skeletal muscle binds to a sodium/potassium channel and opens it. This is an example of ________.

a ligand-gated channel

Which of the following statements is not true?

a lymphocyte has receptors for multiple different antigens

In which of the following species should natural selection favor the highest proportion of juxtamedullary nephrons?

a mouse living in a desert

Which of these observations illustrate the developmental plasticity of the human nervous system?

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 when activity at a synapse correlates with the activity of other synapses, that synaptic connection is reinforced.

Fight-or-flight reactions include activation of the _____.

adrenal medulla, leading to increased secretion of epinephrine

When a person drinks alcohol, the rate of urination increases. Which of the following best accounts for the increase in urination above normal rates?

alcohol inhibits the release of ADH

A patient who has a high level of mast cell activity, dilation of blood vessels, and acute drop in blood pressure is likely suffering from _____.

anaphylactic shock immediately following exposure to an allergen

A physician finds that a nine-year-old male patient is entering puberty much earlier than usual. Such a condition is most likely the result of a tumor in the ________.

anterior pituitary, producing elevated levels of gonadotrophins

Choose the correct match of glial cell type and function.

astrocyte: promote blood flow and regulation of ion concentrations

At the time of implantation, the human embryo is called a _____.

blastocyst

Osteoporosis is a condition in which the density of bones is decreased so much that the individual is at a higher risk of fractures. The more calcium in the bones, the better the bone density. Which of the following would produce the greatest increase in bone calcium levels?

calcitonin injection

The simultaneous arrival of graded depolarization and a graded hyperpolarization of equal but opposite magnitude at a particular location on the dendritic membrane is likely to _____.

cancel each other out, making it appear as if there was no change in membrane potential

Suppose a particular neurotransmitter causes an IPSP in postsynaptic cell X and an EPSP in postsynaptic cell Y. A likely explanation is that __________.

cells X and Y express different receptor molecules for this particular neurotransmitter

In humans, control of balance and coordinated movements are associated with increased activity in the ________.

cerebellum

The central canal of the spinal cord and the ventricles of the human brain contain a filtrate of the blood, called _____.

cerebrospinal fluid

Septic shock, a systemic response including high fever and low blood pressure, is a response to _____.

certain bacterial infections

Which of the following correctly displays the sequence of developmental milestones?

cleavage - blastula -gastrula

The first stage of embryonic development is _____. This process produces _____.

cleavage... a cluster of cells

The force driving simple diffusion is _____, while the energy source for active transport is _____.

concentration gradient; ATP

Biological rhythms in animals isolated from light and dark cues ________.

continue to have cycles of approximately 24 hours' duration; some more rapid, some slower

At the neuromuscular junction, the neurotransmitter acetylcholine (ACh) is degraded by acetylcholinesterase. If a neurophysiologist applies the naturally occurring acetylcholinesterase inhibitor, onchidal (produced by the mollusc Onchidella binneyi), to a synapse, what would you expect to happen?

convulsions due to constant stimulation

In response to stress, the adrenal gland promotes the synthesis of glucose from noncarbohydrate substrates via the action of the steroid hormone ________.

cortisol

The archenteron of the developing sea urchin eventually develops into the _____.

digestive tract

The hormone epinephrine causes opposite effects in two populations of target cells because _____.

each set of cells has different receptor-transduction mechanisms

What major advantage is conveyed by having a system of adaptive immunity?

enables rapid defense against an antigen that has already been encountered

During the early development of a human embryo, the _____ eventually forms the _____.

epiblast; ectodermal, mesodermal, and endodermal tissue

The membrane potential in which there is no net movement of the ion across the membrane is called the _____.

equilibrium potential

Opening all of the sodium channels on an otherwise typical neuron, with all other ion channels closed (which is an admittedly artificial setting), should move its membrane potential to ________.

equilibrium potential for sodium

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

flame bulb; flatworm

Cells move to new positions as an embryo establishes its three germ-tissue layers during _____.

gastrulation

Analysis of a blood sample from a fasting individual who had not eaten for 24 hours would be expected to reveal high levels of ________.

glucagon

In adult humans, short-term memory relies on connections in the _____ whereas long-term memories appear to be based in the _____.

hippocampus... cerebral cortex

The regulation of body temperature derives from the activity of the _____.

hypothalamus

Tetrodotoxin blocks voltage-gated sodium channels, and ouabain blocks sodium-potassium pumps. If you added both tetrodotoxin and ouabain to a solution containing neural tissue, what responses would you expect?

immediate loss of action potential with gradual shift of resting potential

Even in the absence of sperm, metabolic activity in an egg can be artificially activated by _____.

injection of calcium ions into the cytosol

An example of antagonistic hormones controlling homeostasis is _____.

insulin and glucagon in glucose metabolism

During frog development, the blastocoel ________.

is replaced by the expanding archenteron

The body fluids of an osmoconformer would be ________ with its ________ environment

isoosmotic; seawater

The motor (somatic nervous) system can alter the activities of its targets, the skeletal muscle fibers, because _____.

its signals bind to receptor proteins on the muscles

Compared to wetland mammals, water conservation in mammals of arid regions is enhanced by having more _____.

juxtamedullary nephrons

If a person loses a large amount of water in a short period of time, he or she may die from dehydration. Antidiuretic hormone (ADH) can help reduce water loss through its interaction with its target cells in the _____.

kidney

emotion, motivation, olfaction, behavior, and memory, in humans, are mediated by the _____.

limbic system

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

limbic system - motor control of speech

Control of respiration and circulation are associated with the ________.

medulla oblongata

In sea urchins, the "fast block" and the longer lasting "slow block" to polyspermy, respectively, are _____.

membrane depolarization and the cortical reaction

A certain cell type has existed in the blood and tissue of its vertebrate host's immune system for over 20 years. One day, it recognizes a newly arrived antigen and binds to it, subsequently triggering a secondary immune response in the body. Which of the following cell types most accurately describes this cell?

memory cell

The pattern of embryonic development in which only the cells lacking yolk subsequently undergo cleavage is called _____.

mesoblastic development, which is typical in birds

The "threshold" potential of a membrane is the _____.

minimum depolarization needed to operate the voltage-gated Na+ and K+ channels

One of the complications of Alzheimer's disease is an interference with learning and memory. This disease would most likely involve _____.

molecular and structural changes at the synapse

Cerebrospinal fluid can be described as which of the following? I) functioning in transport of nutrients and hormones through the brain II) a product of the filtration of blood in the brain III) functioning to cushion the brain IV) filling spaces between glial cells and neurons in the gray matter

only I, II, and III

If a doctor attempts to trigger the patellar tendon reflex and a lack of response occurs, what are potential regions where pathology might exist? I) the brain II) the knee III) the spinal cord

only II and III

The steroid hormone aldosterone affects only a small number of cells in the body because ________.

only target cells contain aldosterone receptors

A cluster of tumor cells that produces and secretes growth factors to induce surrounding cells to grow and divide is showing which type of cell-to-cell signaling?

paracrine

Mucus occurs in both the respiratory and digestive tracts. What is its main immunological function?

physically trapping pathogens

If the apical ectodermal ridge is surgically removed from an embryo, it will lose _____.

positional information for limb-bud pattern formation

Sexual reproduction ________.

produces offspring with greater genetic variability in comparison to asexual reproduction

Which of the following would not help a virus avoid triggering an adaptive immune response?

producing proteins very similar to those of other viruses

In a lactating mammal, the two hormones that promote milk synthesis and milk release, respectively, are _____.

prolactin and oxytocin

Yearly vaccination of humans for influenza viruses is necessary because _____.

rapid mutation in flu viruses alters the surface proteins in infected host cells

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

reabsorption

One-way synaptic transmission occurs because ________.

receptors for neurotransmitters are mostly found on the postsynaptic membrane

Birds secrete uric acid as their nitrogenous waste because uric acid _____.

requires little water, therefore reducing body mass

Clonal selection and differentiation of B cells activated by antigen exposure leads to the production of _____.

short-lived plasma cells that secrete antibodies for the antigen

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 _____.

slightly permeable to sodium ions

enner's successful use of cowpox virus as a vaccine against the smallpox virus was due to the fact that _____.

some epitopes are common to both viruses

Identify the role(s) of follicle-stimulating hormone (FSH) in human reproduction.

stimulates growth of new follicles in the ovary; promotes activity of sertoli cells, which nourish developing sperm within the seminiferous tube

Preparation for the fight-or-flight response includes activation of the _____ nervous system

sympathetic

The point of connection between two communicating neurons is called the _____.

synapse

A primary response by the Leydig cells in the testes to the presence of luteinizing hormone is an increase in the synthesis and secretion of _____.

testosterone

When antibodies bind antigens, the clumping of antigens results from _____.

the antibody would have at least 2 binding regions

The cortical reaction of sea urchin eggs functions directly in

the formation of a fertilization envelope

After the depolarization phase of an action potential, the resting potential is restored by ________.

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

In a simple synapse, neurotransmitter chemicals are released by _____.

the pre-synaptic membrane

In close comparisons, external fertilization often yields more offspring than does internal fertilization. However, internal fertilization typically offers the advantage that _____.

the smaller number of offspring produced often receive a greater amount of parental investment

Birds, reptiles, and mammals are called "amniotes" because _____.

they have extra-embryonic membranes that develop into an aqueous environment in which development occurs

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?

to make sure that the effect is not occurring through actions in the nervous system

Uterine implantation due to enzymatic digestion of the endometrium is initiated by the _____.

trophoblast

Action potentials are normally carried in only one direction: from the axon hillock toward the axon terminals. If you experimentally depolarize the middle of the axon to threshold, using an electronic probe, then _____.

two action potentials will be initiated, one going toward the axon terminal and one going back toward the hillock

The advantage of excreting nitrogenous wastes as urea rather than as ammonia is that ________.

urea is less toxic than ammonia

Among human males, both semen and urine normally travel along the _____.

urethra

A strain of fruit fly lacks the ability to produce Dicer-2 protein. You might expect this strain to be more susceptible to ________ infections.

viral

In an animal that switches between sexual and asexual reproduction, when is sexual reproduction more likely to occur?

when conditions for survival are unfavorable