wsu biology 251 exam 1

which of the following accurately represents the order of complexity for the organization of the body, from least to most complex?

d. cells, tissues, organs, organ systems

which primary tissue forms a continuous layer that separates the internal environment from the external environment?

a. epithelial tissue

what tissue specialized for generating electrical signals called action potentials?

c. nervous

true or false, exocrine glands secrete hormones directly into the bloodstream.

b. false

homeostasis is a term which describes the processes whereby the body....

c. maintains the internal environment in a state compatible with life

what is the primary mechanism for maintaining homeostasis?

b. negative feedback

for most of homeostasis mechanisms, a ... detects a change in a regulated variable and sends that information to a(n) ... which relays signals to a(n) ..., usually a muscle or a gland to bring about a change.

a. sensor: integrating center: effector

in direct cell-cell communication, ions and small molecules originating within one cell can diffuse directly into a neighboring cell through?

c. gap junction

in passive transport, ions and molecules tend to move across the cell membrane from?

b. the side of high concentration to low concentration

molecules with high lipid solubility are capable of crossing the membrane.

a. directly through the membrane by simple diffusion

the concentration of an ion inside a cell is 0.3%. the concentration of this same ion outside the cell is 0.1%. how would this cell be able to move more of this ion inside the cell?

b. by using an active transporter

which of the following transport mechanisms is passive?

c. the movement of sodium through ion channels

what transport process uses membrane transporters that directly release energy from ATP to move ions or molecules form areas of low concentration to areas of high concentration?

b. primary active transport

what type of ion channels in cell membranes are always open and, therefore, constantly allows ions to move across the membrane?

d. leak channels

for facilitated diffusion, the carrier is a transmembrane protein that moves molecules across the membrane through?

e. changes in configuration (shape) of the transporter, thus picking up the molecule on one side of the membrane and releasing it on the other side.

which of the following membrane transport mechanisms requires the use of metabolic energy released from ATP?

d. both primary and secondary active transport

in active transport, the affinity (binding strength) of the carrier protein for the molecule being transported is greater on which side of the membrane?

c. on the side where the molecule is in lower concentration

in secondary active transport with sodium, which of the following is FALSE?

e. the molecule being co-transported with sodium always moves from the side of the membrane where it has a high concentration to the side where it has a low concentration

true or false, the rate at which molecules are transported by primary active transport is determined by both the rate of transport of individual pumps and by the total number of pumps in the membrane.

a. true

for indirect communication between cells, a ... cell secretes a chemical messenger that binds to a specific ... on the ... cell.

c. secretory : receptor : target

what is the mode of action of a chemical messenger that, when released, binds to receptors on the same cell that released the messenger?

b. autocrine

which of the following will NOT affect the magnitude of a cell's response to a specific chemical messenger?

e. the size of the messenger

chromic exposure to a chemical messenger ... the receptor population for that chemical messenger on the target cell, thus reducing the cell's response to the messenger.

d. down regulates

communication across a synapse is initiated by the release of a neurotransmitter from the ... region of the presynaptic neruon.

b. axon terminal

the neurotransmitter that is released from the presynaptic neuron must diffuse across the ... to reach receptors on the postsynaptic neuron.

e. synaptic cleft

what is a molecule that is similar in structure to a chemical messenger and binds with that messenger's receptor to stimulate similar response from the target cell?

d. agonist

heroin overdose is usually treated with an opioid ... such as naloxone (narcan), which prevents heroin from binding to opioid receptors and reverses the effect of heroin on the body.

a. antagonist

on neuron axons, when voltage-gated sodium channels open, the concentration gradient for sodium across the membrane is such that the net sodium movement is directed ..., thereby causing the cells membrane potential (Vm) to become more ...

a. into the cell : positive

voltage-gated calcium channels in the axon terminals open in direct response to which of the following?

b. arrival of an action potential at the axon terminal

a change in cell's membrane potential, such that the inside of the cell membrane becomes more positive than the resting membrane potential (Vm), is referred to as a?

a. depolarization

on what portion of the neuron do action potentials propagate?

d. axon

the depolarization phase (phase 1) of the action potential is generated by a rapid?

a. opening of voltage-gated sodium (Na+) channels

the repolarization phase (phase 2) of action potentials is primarily due to?

e. potassium (K+) diffuses out of the cell through open voltage-gated potassium channels

during which of the following states of action potential are the voltage-gated sodium channels closed and incapable of opening, i.e., "locked?"

c. during the absolute refractory period

how can action potentials relay information to the brain about the intensity of a stimulus, such as distinguishing between a hot and warm skin temperature?

b. due to the frequency of action potentials generated by sensory neurons that detect temperature

as an action potential is propagated (conducted) away from the axon hillock, why does propagation continue in only one direction?

a. the region just behind the action potential is in the absolute refractory period

in neurons with myelinated axons, where do action potentials occur?

b. at the nodes of ranvier

true or false, if a depolarizing graded potential remains above threshold once it reaches the axon hillock of a neuron, an action potential will be generated.

a. true

which of the following best describes the function of the myelin sheath covering the axon of certain neruons?

e. to increase the conduction velocity of action potentials down the axon

what is the most abundant neurotransmitter used by the nervous system?

acetylcholine (Ach)