BIOL 212 SI, MollyDr. Coffman and Dr. Peterson

EXAM 4 REVIEW4/16/15

Nervous System

Which of the following cells or structures is part of the peripheral nervous system?

a. an interneuron in your brain b. the spinal cord c. the cell body of a sensory neuron on your tongue d. the hypothalamus e. an intestinal epithelial cell

A rattlesnake just tried to bite you. Your pulse is racing and you notice your pupils are wide open when you step into your car and look in your rearview mirror. What part of your autonomic nervous system is activated?

a. Myelencephalon b. Neocortex c. Sympathetic d. Peripheral e. Parasympathetic

As an action potential moves along an axon, the membrane potential changes. Which of the following best describes the molecular mechanisms that cause these changes in membrane potential?

a. Action potentials are mediated by changes in transcription. Different gene expression patterns cause different membrane potentials.

b. As an electron moves along the length of the axon, it transiently heats the membrane, and this changes the membrane potential.

c. Action potentials are mediated by calcium-mediated exocytosis of neurotransmitters. When the vesicles fuse with the membrane, this changes the membrane potential.

d. Sodium and potassium ions speed along the length of the axonal cytoplasm, and this changes the local membrane potential as the action potential passes through.

e. Action potentials are mediated by voltage-gated sodium and potassium channels, and diffusion of ions across the membrane cause the changes in membrane potential.

The location for chemical communication between a neuron and a target cell is called the

a. motor neuron b. synaptic cleft c. oligodendrocyte d. acetylcholine e. axon hillock

In a neuron, the nucleus is located in the a. dendritic region. b. axon hillock. c. axon. d. soma. e. axon terminals.

In general, the input processes of a neuron in the central nervous system are referred to as

a. axons b. synaptic cleft c. neuromuscular junction d. dendrites e. synaptic terminals

Which of the terms below best describes neurons that make local connections between neurons in the brain?

a. motor neurons b. sensory neurons c. interneurons d. hub neurons e. transit neurons

Which term below best describes neurons that are responsible for stimulating contraction of muscles in your leg?

a. motor neurons b. sensory neurons c. interneurons d. hub neurons e. transit neurons

Which term below best describes neurons that are responsible for sensing pressure in your skin?

a. motor neurons b. sensory neurons c. interneurons d. hub neurons e. transit neurons

Which is NOT a factor that contributes to the resting potential? a. Ion specific channels allowing passive movement of ions b. Na+/K+ -ATPase c. Binding of neurotransmitters to ligand-gated ion channels d. Negatively charged molecules such as proteins that are more

abundant inside the cell e. All the above contribute to the resting potential

The inside of a plasma membrane of a neuronal axon generally has a negative resting potential relative to the outside of the cell. Which of the following changes would result in depolarization of the membrane?

a. Na+ entering the cell b. K+ leaving the cell c. Retraction of the axon d. Neurotransmitter release from the cell

In the two cellular compartments shown above, K+ is moving across the membrane from the left to the right. Why is K+ moving from the left to the right?

a. K+ is moving down its concentration gradient b. K+ is moving down its electrical gradient c. Cl- is attracting K+ d. K+ is moving because the membrane is impermeable to Cl-

If the K+ channel closed, so the ions were trapped in the compartments as shown above, what would the voltage of the right side of the cell be in relation to the left?

a. Equal b. Negative c. Positive d. Cannot be determined

The response of a postsynaptic cell is determined by: a. A. The type of neurotransmitter released at the synapse. b. B. The type of receptors the postsynaptic cell has. c. C. The number of Na+ channels in the postsynaptic membrane d. D. The number of K+ channels in the postsynaptic membrane. e. All of the above f. A and C only

How does a sensory system provide information about the intensity of a stimulus?

a. The larger the action potential, the larger the stimulus. b. by the release of both dopamine and acetylcholine the cell

senses a larger stimulus c. More chloride channels close, thereby creating greater

transmitter uptake. d. Via action potentials, the frequency of action potential

firing is related to the intensity of the stimulus. The process whereby incoming sensory information is converted to an electrical signal is known as:

a. threshold potential b. an action potential c. perception d. sensory transduction e. reception

As a sensory neuron in your skin is lightly stimulated, a receptor potential is generated. However, the membrane potential change in this sensory neuron does not reach threshold. Most likely, you perceived that stimulus as a sensation of:

a. pain b. heat c. cold d. intense pressure e. I did not perceive that, since the threshold potential was not

achieved, I could not perceive that sensation.

What type of stimulus is responsible for activating your cones and rods?

a. mechanical energy b. thermal energy c. chemical energy d. electromagnetic energy e. pressure energy

Touch receptors in your skin are activated by what type of stimulus?

a. electromagnetic energy b. nuclear energy c. mechanical energy d. photonic energy e. sonic energy

How do neurons establish differential concentrations of ions inside and outside the cell?

a. active transport b. osmosis c. simple diffusion d. facilitated diffusion

What factors contribute to the resting potential in a nerve cell?

a. sodium-potassium pumps, ligand-gated ion channels, negatively charged molecules (i.e. proteins) are more abundant inside the cells

b. sodium-potassium pumps, ion specific channels, positively charged molecules (i.e. proteins) are more abundant inside the cells

c. sodium-potassium pumps, ion specific channels, negatively charged molecules (i.e. proteins) are more abundant inside the cells

d. sodium-potassium pumps, ion specific channels, positively charged molecules (i.e. proteins) are more abundant outside the cells

Initiation of an action potential involves:

a. membrane hyperpolarization b. Sodium channel opening c. Potassium channel opening d. refractory period e. Potassium channel closing

In an action potential, the return to the resting potential involves: a. A. Cl- channel inactivation b. B. Na+ channel inactivation c. C. Na+ channel opening d. D. K+ channel closing e. E. K+ channel opening f. A, B and D g. B and D h. B and E

Which of the following features allow neurons to rapidly conduct action potentials to muscles in your foot? (1) myelination of the axon provided by oligodendrocytes

(2) a large diameter axon (3) a small, narrow diameter axon (4) myelination of the axon provided by Schwann cells

a. 1 and 2 b. 1 and 3 c. 2 and 4 d. 3 and 4

How does our nervous system organize information about our sensory environment?

a. by opening more voltage-gated and ligand-gated ion channels b. by forming topographic representations of that particular

sensory information c. by relaying information using interneurons through the spinal

cord d. by increasing the amplitude of the receptor potentials

In some plants electrical signals can travel from cell to cell via:

a. electrical synapses b. chemical synapses c. chloroplast junctions d. plasmodesmata

Why are squid giant axons used in neuroscience research? a. their action potentials are stronger and hence easier to detect. b. they do not have any refractory period and so can be used repeatedly. c. they have a large diameter and so can be easily impaled by electrodes to

record their membrane potential. d. because squid live in saltwater their axons can be easily kept alive in a

saline solution.

In a resting neuron, the concentration of potassium ions (K+) is: a. higher inside the cell than outside of the cell b. lower inside the cell than outside of the cell c. the same inside and outside the cell d. it varies with different neurons

In a resting neuron, the concentration of sodium ions (Na+) is: a. higher inside the cell than outside of the cell b. lower inside the cell than outside of the cell c. the same inside and outside the cell d. it varies with different neurons

Which of the following factors contribute to the resting potential in a nerve cell?

a. Ion specific channels that allow passive movement of ions b. An ATPase-driven sodium-potassium ion pump.

c. Negatively charged molecules such as proteins that are more abundant inside the cell.

d. All the above contribute to the resting potential Which is involved in repolarizing a neuronal membrane following an action potential?

a. Vesicle fusion b. Ligand gated channels c. Opening K+ channels d. Opening Na+ channels

Which is involved in depolarizing a neuronal membrane during an action potential? a. Vesicle fusion b. Ligand gated channels c. Opening K+ channels d. Opening Na+ channels

In an action potential, the return to the resting potential involves:

a. Na+ channel opening and K+ channel closing b. Ca+ binds to vesicles to induce exocytosis

c. Na+ channel inactivation and K+ channel opening d. None of the above.

What do potassium ions (K+) do during an action potential? a. they exit the neuron via vesicle exocytosis. b. they bind to vesicles to induce exocytosis. c. they exit the neuron via voltage-gated potassium channels. d. they exit the neuron via the sodium-potassium pump.

What do sodium ions (Na+) do during an action potential? a. they enter the neuron via sodium-potassium pumps and

depolarize the membrane. b. they exit the neuron through voltage-gated sodium channels and

hyperpolarize the membrane. c. they enter the neuron via voltage-gated sodium channels and

depolarize the membrane. d. they enter the synaptic cleft via exocytosis.

Which of the following statements about graded potentials in neuronal signaling is NOT TRUE?

a. They sometimes involve membrane hyperpolarization b. They sometimes involve membrane depolarization c. They vary in amplitude according to the strength of a stimulus d. They determine whether threshold potential is reached for

initiating an action potential e. All of the above statements are true

Action potentials are normally conducted in just one direction on an axon because a. voltage gates prevent back conductance b. Na+ channels are inactivated during the refractory period c. myelin sheaths provide directional guidance d. there is an electrochemical gradient toward the end of the axon e. all of the above

If you artificially depolarize the membrane to start an action potential in the middle of an axon, what will happen?

a. Nothing. Action potentials can only initiate at the axon hillock.

b. The action potential will be conducted in just one direction (toward the synapse).

c. The action potential will travel in both directions. d. The neuron will die.

Myelination of axons is important because a. it slows the speed of neural impulse conductance b. it enhances neurotransmitter sensitivity c. it enhances the speed of neural impulse conductance d. it increases the strength of action potentials e. it lowers threshold potential

Individuals with multiple sclerosis have longer reaction times to various stimuli. This can be explained by the following:

a. They have a defect in voltage-gated sodium channels which are required to initiate action potentials.

b. They have degradation of myelin sheaths resulting in slower conductance of signals.

c. They have a defect in neurotransmitter release, so it takes a longer time to transmit sufficient numbers of graded potentials to the post-synaptic cell.

d. They have abnormal ladder-like connections in their cerebral cortex, resulting in impaired decision-making ability.

Which of the following statements about myelin sheaths on axons is NOT TRUE

a. They are secreted by the nodes of Ranvier b. They are composed of layers of glial cell membranes wrapped

around the axon c. They produce saltatory neural signal conductance d. They increase the speed of neural signal conductance e. All these statements are true

A neurotransmitter is a. a signaling molecule that influences membrane potential of a postsynaptic

cell b. an electro-chemical impulse c. a type of glial cell d. a type of membrane vesicle e. a gap junction that connects two neurons

Postsynaptic cells a. Receive signals by endocytosis b. Always respond to signals with an action potential c. Are always neurons d. Often contain neurotransmitter receptors e. Are connected to presynaptic cells by gap junctions

In neural signaling, ligand-gated ion channels a. are ion channels that are opened (or closed) in response to

binding a neurotransmitter

b. are gap junctions that allow Na+ transport across a synapse c. are voltage-gated Ca++ channels that trigger neurotransmitter

uptake d. are sensory neurons that detect electromagnetic stimuli e. direct chemotaxis of axons to guide neural connections during

development

Presynaptic release of neurotransmitter a. Is triggered by a graded potential b. Occurs through gap junctions c. Requires electrical synapses d. Occurs via endocytosis e. Occurs via exocytosis

Predict the effect of a chemical that blocked voltage-dependent Calcium ion channels at the synaptic ending of an axon.

a. The axon could not generate an action potential. b. The cell would continually release neurotransmitter via

vesicle exocytosis. c. The calcium channels would not open, and this would inhibit

neurotransmitter release. d. It would not have an effect. Only sodium and potassium

channels are voltage-gated; Calcium channels are ligand-gated.

A neurotoxin that stimulated acetylcholine release would most likely cause

a. numbness b. hallucinations c. ATP depletion d. muscle cramping e. dizziness

The peripheral nervous system

a. Controls cognition b. Provides sensory input c. Commands the central nervous system d. All of the above

Approximately how long does a single action potential take? a. 3 milliseconds b. 30 microseconds c. 180 milliseconds d. 250 milliseconds

Approximately what is the normal resting potential of a neuron? a. -100 mV b. -70 mV c. -30 mV d. 30 mV

Approximately how many neurons do you have in your brain? a. 100 million b. 1 billion c. 10 billion d. 100 billion

Which lobe of the brain is most responsible for vision? a. Parietal lobe b. Occipital lobe c. Temporal lobe d. Frontal lobe

Which lobe of the brain is most responsible for conscious thought? a. Parietal lobe b. Occipital lobe c. Temporal lobe d. Frontal lobe

Which of the following is most highly developed in human brains compared to other mammals?

a. Medulla oblongata b. Hypothalmus c. Cerebral cortex d. Midbrain e. Hindbrain

How does a sensory system provide information about the intensity of a stimulus?

a. Sensory receptors produce different frequency of action potentials depending on intensity of a stimulus

b. Sensory receptors produce different amplitude of action potentials depending on intensity of a stimulus

c. By the release of both dopamine and acetylcholine the cell senses a larger stimulus

d. More chloride channels close, thereby creating greater transmitter uptake.

One type of mechanosensors

a. Responds to chemical pheromones released by scent glands. b. Detects specific wavelengths of light and transmits action

potentials to the occipital lobe via the optic nerve. c. Produces different amplitude of action potentials depending on

intensity of a stimulus d. Contain stretch-induced ion channels that lead to membrane

depolarization when cells are deformed.

We detect different auditory tones because different sound frequencies a. cause different action potential amplitudes in auditory

neurons b. are processed by different auditory ganglia in the ear lobe c. travel at different speeds through the vestibular fluids in

the ear d. vibrate different parts of the cochlea, which are detected by

different mechanosensory cells.

We detect motion and position because a. statoliths in our ears cause different action potential

frequencies in statitory neurons b. hair sensory cells detect movements of the vestibular fluids

in our ears c. gravity pulls hairs on sensory cells downward d. proprioceptors emit neurotransmitters in the direction of

gravity e. ossicles vibrate different parts of the cochlea in response to

movement and gravity, which is detected by different mechanosensors

Invertebrates use the following system to detect gravity and maintain body orientation

a. A sphere of sensory hair cells contains a statolith that moves in response to gravity.

b. hair sensory cells detect movements of vestibular fluids in the semicircular canals.

c. gravity pulls hairs on sensory cells downward

d. proprioceptors emit neurotransmitters in the direction of gravity

e. ossicles vibrate different parts of the cochlea in response to movement and gravity, which is detected by different mechanosensors

Some plants respond to touch by

a. transmitting action potentials from cell to cell via plasmodesmata

b. opening ion channels in specialized cells c. Ions and water flow out of specialized cells, resulting in

cell flattening and leaf movement. d. All of the above.

Folding of Mimosa (sensitive plant) leaves in response to touch a. is triggered by an action potential b. is controlled by hormones c. is controlled by neurotransmitters d. is a stomatal response

In neural signaling, ionotropic receptors a. are ion channels that are opened (or closed) in response to

binding a neurotransmitter

b. are gap junctions that allow Na+ transport across a synapse c. are voltage-gated Ca++ channels that trigger neurotransmitter

uptake d. are sensory neurons that detect electromagnetic stimuli e. direct chemotaxis of axons to guide neural connections during

development

In a resting neuron, the negative charge inside the cell results from a. Of the energy provided by ATP

b. Ion-selective channels allow diffusion of K+

c. The diffusion (concentration) gradient of K+ ions opposes the electrical gradient

d. The cell membrane is impermeable to Na+ or Cl- ions. e. 2 & 3 f. All of the above

Sensory receptors a. All connect to the same sensory center in the brain b. Interpret the quality of input stimuli c. Produce different frequency of action potentials depending on

intensity of a stimulus

d. Produce different amplitude of action potentials depending on intensity of a stimulus

e. All of the above

39. The figure shows traces from action potentials of normal neurons (control) and neurons treated with alpha-dendrotoxin (α-DTX). Dendrotoxin most likely affects

a. active transport b. neurotransmitter release c. Ca++ channel opening d. Na+ channel opening e. K+ channel opening

Muscle/locomotion

Which of the following is true of the arrangement of actin and myosin filaments within a myofibril?

a. Thin filaments extend the entire way across the sarcomere b. Thick filaments are attached to the end walls of the sarcomere c. Thin filaments are attached to the end walls of the sarcomere d. Thick filaments run towards the center from each side of the

sarcomere, leaving a gap in the middle e. Thin filaments traverse the sarcomere center but do not reach

the end walls

After ACh binds to the receptors in the muscle fiber plasma membrane, Na+ floods into the muscle fiber. Why?

a. Na+ signals for the muscle fiber to quit binding to ACh b. Na+ is a part of the ACh molecule that broke off inside the

cell c. Na+ is so small that it is always diffusing across the cell

membrane d. Na+ depolarizes the cell membrane to initiate an action

potential e. Na+ signals for ACh to be removed from the synaptic cleft by

the enzyme acetylcholinesterase

Hydrostatic skeleton is one in which

a. A hard, exterior coating is used b. A system of hard plates is used c. Fluid under pressure is used d. Skeletal pieces are embedded in a gelatin-like material

Each skeletal muscle cell constitutes a single a. motor unit b. sarcolemma c. myofibril d. sarcomere e. muscle fiber

Which of the following is a common neurotransmitter found in vertebrate neuromuscular junctions?

a. Serotonin b. Glutamate c. Dopamine d. Acetylcholine e. Epinephrine

Cross-bridges form between _____ and _____ during muscular contraction. a. actin, myosin b. actin, tropomyosin c. myosin, troponin d. myosin, tropomyosin e. troponin, calmodulin

Neuromuscular junctions involve a. a neural dendrite, a gap junction, and the sarcoplasmic

reticulum b. a synapse, a myofibril, and troponin c. an axon terminal, acetylcholine, and ligand gated ion channels d. a synaptic cleft, norepinephrine, and an axon terminal e. an electrical synapse, a node of Ranvier, and acetylcholine

An action potential in a muscle cell a. triggers Ca++ release from the sarcoplasmic reticulum b. is propagated through voltage gated Ca++ channels c. is initiated by myosin binding to actin filaments d. causes release of acetylcholine e. all of the above

What would happen to a myofibril if ATP were depleted from a muscle cell?

a. Myosin could not release from actin b. Myosin could not bind actin c. Myosin could not perform a power stroke d. Actin would depolymerize

e. Myosin could not hydrolyze

When during a muscle contraction sequence is ATP hydrolyzed to provide power?

a. cross bridge formation (binding) b. power stroke c. Detachment of myosin from actin d. Reactivation of myosin heads e. to remove tropomyosin from the binding sites on actin

Calcium in skeletal muscle cells a. Creates an action potential b. Binds myosin c. Binds actin d. Regulates availability of myosin binding sites on actin e. Is stored in the symplastic infundibulum

Biotechnology

Why is PCR (polymerase chain reaction) so useful? a. PCR can cut DNA in very specific places, to isolate specific

genes. b. PCR is a process where a vector is inserted into a bacterial

cell, where the gene of interest can be expressed. c. PCR produces many, many copies of a specific region of DNA. d. PCR is a mostly outdated process that scientists rarely use

now, so it is not very useful.

Researchers and doctors recently treated a B cell leukemia patient’s T cells with a modified form of HIV, allowing those cells to recognize and destroy B cells. Why did they use HIV?

a. Once the T cells are transferred back into the patient, the virus will spread quickly, providing even more protection against the leukemia.

b. HIV is able to bind to and infect T cells efficiently. c. HIV is able to bind to and infect B cells efficiently d. HIV is the only virus that can infect human cells

When generating a transgenic cell or organisms, researchers often also include a marker such as green fluorescent protein (GFP). Why?

a. These markers increase the efficiency of gene transfer. b. The markers increase the expression of the gene of interest. c. The markers are often pretty. d. The markers are often easier to screen for than the gene of

interest, and signal that the gene transfer worked.

Golden Rice and Bt corn are just a few examples of genetically modified organisms (GMOs) intended for human consumption. What is a possible

risk of generating plants that make their own insecticides, as is the case for Bt corn?

a. The transgenes were inserted by viral infection, so these viruses could become active again and infect other plants.

b. Cross-pollination from the transgenic plants to wild relatives could spread the gene to other species.

c. These transgenes could be transferred to humans through consumption of the plant.

d. All of the above.