Biology 191: Exam II
Terms in this set (117)
The "information receiving" section of a neuron is its _____.
A simple nervous system
includes sensory information, an integrating center, and effectors.
The nucleus and most of the organelles in a neuron are located in the
The point of connection between two communicating neurons is called the
In a simple synapse, neurotransmitter chemicals are released by
the presynaptic membrane.
The operation of the sodium-potassium "pump" moves
sodium ions out of the cell and potassium ions into the cell.
ATP hydrolysis directly powers the movement of
Na+ out of cells.
Two fundamental concepts about the ion channels of a "resting" neuron are that the channels
open and close depending on stimuli, and are specific as to which ion can traverse them.
The "selectivity" of a particular ion channel refers to its
permitting passage only to a specific ion.
In a neuron, during the depolarization phase that may trigger an action potential _____.
some voltage-gated sodium channels are open
Select the choice that describes neurons with the fastest conduction velocity for action potentials.
thick, myelinated neurons
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 the
hyperpolarization of the neuron.
A toxin that binds specifically to voltage-gated sodium channels in axons would be expected to
prevent the depolarization phase of the action potential.
The "undershoot" phase of after-hyperpolarization is due to
sustained opening of voltage-gated potassium channels.
Immediately after an action potential passes along an axon, it is not possible to generate a second action potential; thus, we state that the membrane is briefly
In the sequence of permeability changes for a complete action potential, the first of these events that occurs is the
opening of voltage-gated sodium channels.
Saltatory conduction is a term applied to
jumping from one node of Ranvier to the next in a myelinated neuron.
A nerve poison that blocks acetylcholine receptors on dendrites would _____.
reduce the binding of acetylcholine to its receptors on the postsynpatic membrane. The binding of neurotransmitter molecules to their specific receptors on the postsynaptic membrane opens ion channels, which completes the transmission of the impulse to the receiving cell. A nerve poison that blocked the acetylcholine receptors would prevent reception of the signal.
The surface on a neuron that discharges the contents of synaptic vesicles is the
Neurotransmitters are released from axon terminals via
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 the 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?
3 → 2 → 5 → 1 → 4
The activity of acetylcholine in a synapse is terminated by its
degradation by a hydrolytic enzyme on the postsynaptic membrane
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
When several IPSPs arrive at the axon hillock rapidly in sequence from a single dendritic location, hyperpolarizing the postsynaptic cell more and more and thus preventing an action potential, this is an example of
Neurotransmitters affect postsynaptic cells by
-causing molecular changes in the cells.
-altering the permeability of the cells.
-affecting ion-channel proteins.
-initiating signal transduction pathways in the cells.
An amino acid that operates at inhibitory synapses in the brain is
Most of the synapses in vertebrates conduct information in only one direction
because only the postsynaptic cells can bind and respond to neurotransmitters
What happens when a resting neuron's membrane depolarizes?
The neuron's membrane voltage becomes more positive.
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.
-Concentration gradients of potassium (K+) and sodium (Na+) across the plasma membrane represent potential energy.
If the membrane potential of a neuron decreases, the membrane potential _____.
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 first opens sodium channels and then opens potassium channels.
What causes the falling phase of the action potential? Select the best answer.
Inactivation of voltage-gated sodium channels and the opening of voltage-gated potassium channels
The central nervous system is lacking in animals that have
Cephalization, the clustering of neurons and interneurons in the anterior part of the animal, is apparent in
Choose the correct match of glial cell type and function.
astrocytes-metabolize neurotransmitters and modulate synaptic effectiveness
The cerebrospinal fluid is
a filtrate of the blood.
The blood-brain barrier
is formed by tight junctions.
Cerebrospinal fluid can be described as all of the following except
formed from layers of connective tissue.
Preparation for the fight-or-flight response includes activation of the ________ nervous system.
The divisions of the nervous system that have antagonistic, or opposing, actions are the
sympathetic and parasympathetic systems.
The activation of the parasympathetic branch of the autonomic nervous system is associated with
resting and digesting.
Dolphins can be awake and asleep at the same time because _____.
one side of the brain can sleep while the other side maintains swimming and breathing behaviors
Emotion, motivation, olfaction, behavior, and memory, in humans, are mediated by the _____.
Increases and decreases of the heart rate result from changes in the activity of the
The unconscious control of respiration and circulation is associated with the
The suprachiasmatic nuclei are found in the
As vertebrates evolved, the increasingly complex structure of the brain conferred increasingly complex function, especially apparent in the _____.
cerebral complex, which is greatly expanded in nonhuman primates and cetacean
Calculation, contemplation, and cognition are human activities associated with increased activity in the
Which of the following shows a brain structure correctly paired with one of its primary functions?
frontal lobe-decision making
Our understanding of mental illness has been most advanced by discoveries involving the
chemicals involved in brain communications.
An injury to the occipital lobe will likely impair the function of the
primary visual cortex.
he sense described as umami is one of _____
savory and delicious sensation on the tongue
Injury to just the hypothalamus would most likely disrupt _________
regulation of body temperature
Identify the correct statement(s) about glial cells and their functions.
Astrocytes participate in the formation of the blood-brain barrier.
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.
Sexual reproduction includes a reproductive pattern called _____.
Animals utilizing external fertilization are typically ____
Which of the following correctly traces the path of sperm from their site of production to their exit from a man's body?
seminiferous tubule → epididymis → vas deferens → urethra
In humans, oogenesis in comparison to spermatogenesis is different in that _____
oogenesis does not complete meiosis until after fertilization, but spermatogenesis is complete before the sperm leave the body
The anatomical location for the typical union of a sperm and an egg (conception) is the ___
Among the following, the earliest consequence of the acrosomal reaction is ____
the membrane of the egg depolarizing
The first stage of embryonic development is _____. This process produces _____.
cleavage ... a cluster of cells
The mesoderm gives rise to ___
skeletal and muscular systems
Choose the correct developmental sequence of animal development.
fertilization → cleavage → gastrulation → organogenesis
Salamander and insect populations consisting only of genetically identical females lack males because _____
sperm do not fuse with eggs during reproduction, but the eggs develop into embryos anyway
The "reproductive handicap" for sexual reproduction refers to __
have only half the offspring are females
Birds, reptiles, and mammals are called "amniotes" because _____.
they have extra-embryonic membranes that develop an aqueous environment in which development occur
Embryonic cells especially active in assuring nutritional exchange between a pregnant woman and her embryo are found in
An embryonic cell that is "totipotent" is one that can _____.
by itself, give rise to the entire embryo, as cleavage proceeds
Which of the following characterizes parthenogenesis?
An egg develops without being fertilized.
The cortical reaction of sea urchin eggs functions directly in
the formation of a fertilization envelope
Which of the following is not properly paired?
Peaks of LH and FSH production occur during
the period just before ovulation
For which is the number the same in males and females?
meiotic divisions required to produce each gamete
Which statement about human reproduction is false?
The earliest stages of spermatogenesis occur closest to the lumen of the seminiferous tubules.
What is the fundamental difference between male and female vertebrates?
Males produce many, motile gametes and females produce few, stationary gametes
What is the "twofold" cost of sex?
The higher number of female offspring produced by an asexual female
Identify the role(s) of follicle-stimulating hormone (FSH) in human reproduction.
-FSH stimulates the growth of new follicles in the ovary.
-FSH promotes the activity of Sertoli cells, which nourish sperm developing within seminiferous tubules.
The hormone epinephrine causes opposite effects in two populations of target cells because _____.
each set of target cells has different receptor-transduction mechanisms
In their mechanism of action, a difference between lipid-soluble and water-soluble hormones is that _____.
lipid-soluble hormones bind to an intracellular receptor and this hormone-receptor complex binds to DNA
Oxytocin secretion and milk release from the mammary glands of lactating female mammals are initiated by _____.
the physical sensation of the baby sucking at the nipple
Jet lag occurs when a person moves rapidly from one time zone to another, causing conflict between the body's biological rhythm and the new cycle of light and dark. Some scientists suspect that jet lag may result from disruption of the daily cycle of secretion of the hormone known as _____.
Hormones are _____.
chemical signals between cells, transported in blood or hemolymph
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.
Select the correct statement about feedback regulation in endocrine systems.
Some homeostatic control systems rely on pairs of negatively regulated hormone pathways, each counterbalancing the other.
Which hormone is placed into the correct chemical class?
Calcitonin is a peptide hormone.
The anterior and posterior lobes of the pituitary differ in that _____.
many anterior pituitary hormones regulate other endocrine glands whereas posterior pituitary hormones regulate nonendocrine tissues
How does the adrenal gland respond to stress?
The adrenal medulla secretes epinephrine and norepinephrine in response to short-term stress.
Select the example that accurately illustrates this statement: "The endocrine and nervous systems act together to regulate an animal's physiology."
In response to stress, neurosecretory cells in the adrenal medulla release epinephrine and norepinephrine, which mediate various fight-or-flight responses.
The figure shows how glucose homeostasis is maintained by two antagonistic hormones, insulin and glucagon. Select the correct statement about these hormones.
Each of these hormones operates in a simple endocrine pathway.
The closest algal relatives of land plants are _____.
In seedless plants, a fertilized egg will develop into _____.
Which of the following traits was most important in enabling the first plants to move onto land?
he development of sporopollenin to prevent the desiccation of zygotes
The diploid generation of the plant life cycle always _____.
Which of the following is a difference between plants and fungi?
Fungi are heterotrophic, and plants are autotrophic.
Seedless plants include _____.
bryophytes, lycophytes, ferns, whisk ferns, and horsetails
Most bryophytes, such as mosses, differ from all other plants in that they _____.
lack true leaves and roots
What evolutionary development allowed plants to grow tall?
lignified vascular tissue
During the Carboniferous period, forests consisting mainly of _____ produced vast quantities of organic matter, which was buried and later became coal.
ferns and other seedless plants
In contrast to bryophytes, in vascular plants the dominant stage of the life cycle is the _____.
When you look at a pine or maple tree, the plant you see is a _____.
All seed plants _____.
The adaptation that made possible the colonization of dry land environments by seed plants is most likely the result of the evolution of _____.
Gymnosperms were most abundant during the _____.
In pine, the embryo develops within the _____.
The major difference between angiosperms and gymnosperms comes from the _____.
presence or absence of a protective covering over the ovule
Angiosperms are different from all other plants because only they have _____.
Unlike most angiosperms, grasses are pollinated by wind. As a consequence, some unnecessary parts of grass flowers have almost disappeared. Which of the following parts would you expect to be most reduced in a grass flower?
Human survival literally depends on the produce of _____.
Which of the following characteristics of plants is ABSENT in their closest relatives, the charophyte algae?
alternation of generations
A fruit is usually __________
a mature ovary
Select the correct statement about charophytes, a taxon of green algae.
Charophytes and land plants share four distinctive traits.
Which of these facts provides the best support for the hypothesis that plants evolved from green algae?
The chloroplasts of plants and green algae all have both chlorophyll a and b.
Select the correct statement contrasting gametophytes and sporophytes.
Sporophytes are diploid, whereas gametophytes are haploid.
Select the correct statement about the life cycle of a fern.
Plant gametophytes are haploid multicellular bodies.
Select the correct statement describing the life cycle of angiosperms.
Double fertilization in the life cycle of seed plants results in the production of a diploid zygote and a triploid endosperm nucleus.
Which of these structures is a separate generation from the plant sporophyte?
A male gametophyte within a pollen grai