Which of the following does not describe conditions that occur during an action potential?
a) the na+/k+ pump reestablishes resting concentration gradients.
b) after initial depolarization, k+ now has both an electrical and a chemical gradient drawing it out of the cell.
c) na+ enters the cell through voltage-gated channels, causing a reversal of the resting membrane potential.
d) na+ is used to repolarize the membrane.

D) Na+ is used to repolarize the membrane.

Explanation:

Option D is wrong choice because it is K+ which is used to repolarize the membrane not Na+.

As soon as membrane gets depolarized because of influx of Na+ due to opening of voltage gated Na+ channels simultaneous opening of voltage gated K+ channels and closing of Na+ voltage gated channels takes place. As a result of which K+ moves out of the cell leading to drawing of electrochemical gradient out of the cell.

In order to achieve resting membrane potential, more Na+ must be out of the cell and more K+ must be inside the cell. There are many leaky channels on neurons from which Na+ has tendency to leak into the cell while K+ has the tendency to leak outside of the cell. So Na+/K+ pump which is located on the membrane of neuron keeps pushing Na+ outside of the cell and K+ inside the cell so as to maintain resting membrane potential which is -70 mV.

weathering is the answer.

interphase

the period of cell growth when the cell synthesizes new molecules and organelles. the cell is not dividing and it constitutes the majority of the time spent in the cell cycle

prophase

changes occur in the nucleus and cytoplasm. the chromatin condenses to form structures (sister chromatids) visible with a light microscope and the mitotic spindle begins to form, but the nucleus is still in tact

prometaphase

the nuclear envelope fragments and the spindle microtubules attach to the kinetochores of the sister chromatids

metaphase

all the cell's duplicated chromosomes are lined up at an imaginary plane equidistant between the poles of the mitotic spindle

anaphase

begins when sister chromatids separate from each other and ending when a complete set of daughter chromosomes arrives at each of the two poles of the cell

telophase

the daughter nuclei form at the two poles of a cell

cytokinesis

the division of a cytoplasm to form two separate daughter cells. usually occurs during telophase during mitosis. this and mitosis make up to mitotic (m) phase of the cell cycle