Which of the following statements correctly describe(s) the driving forces for diffusion of na+ and k+ ions through their respective channels? select all that apply. which of the following statements correctly describe(s) the driving forces for diffusion of na+ and k+ ions through their respective channels? select all that apply. the diffusion of na+ ions into the cell is facilitated by the na+ concentration gradient across the plasma membrane. the diffusion of na+ ions into the cell is impeded by the electrical gradient across the plasma membrane. the diffusion of k+ ions out of the cell is impeded by the k+ concentration gradient across the plasma membrane. the diffusion of k+ ions out of the cell is impeded by the electrical gradient across the plasma membrane. the electrochemical gradient is larger for na+ than for k+.

The correct answers are :

The diffusion of Na+ ions into the cell is facilitated by the Na+ concentration gradient across the plasma membrane.

The diffusion of K+ ions out of the cell impeded by the electrical gradient across the plasma membrane

The electrochemical gradient is larger Na+ than for K+

Reason:

The transfusion of Na+ or K+ takes place through either ion leakage or  ion pumping. Generally the state of cell is steady  which is represented by the resting membrane potential. To start any movement across the membrane, the membrane potential need to be modulated from the resting position

The first movement starts with the opening of channel for Na+ in the membrane. Since the concentration of Na+ outside the cell is ten times the concentration of Na+ inside the cell, the Na+ ion move into the cell driven by concentration gradient. The concentration gradient of sodium is extremely strong and sodium continues to move into the cell even when the membrane potential becomes zero. As the sodium moves into the cell depolaristaion is caused due to which the negative resting potential of membrane changes from -70 mV to +30 mV. With positive membrane potential, the voltage-gated channels gets opened and both sodium and potassium starts moving across the membrane. K+ moves across the membrane primarily due to the effect of electrical gradient. K+ also move across the membrane through due to concentration gradient but since the concentration difference across the channel is not as high as sodium, it could not open the voltage gate. Thus, Na movement is primarily driven by concentration gradient (in smaller amount by electrical gradient too), K movement is primarily driven by electrical gradient (in smaller amount by concentration gradient too) but the combined effect of both the concentration and electrical gradient is higher for Sodium.

The following statements correctly describe(s) the driving forces for diffusion of Na+ and K+ ions through their respective channels:

Because ions carry a charge (positive or negative), their transport across a membrane is governed not only by concentration gradients across the membrane but also by differences in charge across the membrane (also referred to as membrane potential). Together, the concentration (chemical) gradient and the charge difference (electrical gradient) across the plasma membrane make up the electrochemical gradient.

Consider the plasma membrane of an animal cell that contains a sodium-potassium pump as well as two non-gated (always open) ion channels: a Na+ channel and a K+ channel. The effect of the sodium-potassium pump on the concentrations of Na+ and K+ as well as the distribution of charge across the plasma membrane is indicated in the figure below.

Which of the following statements correctly describe(s) the driving forces for diffusion of Na+ and K+ ions through their respective channels? Select all that apply.

Grade:  9

Subject:  biology

Chapter:  The diffusion of ions

Keywords: the driving forces for diffusion, Na+, K+ ions, channels, plasma membrane

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