Practice Questions - Week 2

Question 1

In the model system shown in the diagram below if the ion channel (selectively permeable to Na+ ) was opened what would be the potential difference between in inside and the outside of the cell be?

1. +30 mV
2. none of the above
3. +64.3 mV
4. +83 mV
5. -83 mV

Answer 1

4.

Question 2

In the model system shown below the membrane-spanning protein is a cation-selective channel. Which of the following will happen when this channel opens?

1. anions will enter the cell
2. Y- ions will leave the cell
3. the membrane potential will become more positive
4. the membrane potential will not change
5. the membrane potential will become more negative

Answer 2

4. the membrane potential will not change

Question 3

When recording the potential difference across an artificial membrane what is the function of the 3 M KCl inside the electrodes?

1. to make the electrodes harder to break
2. to keep the temperature constant
3. to maintain the stability of the plasma membrane
4. to provide electrical continuity between the leads of the voltmeter and the solutions in the chambers
5. to provide a constant supply of KCl in the bathing solutions

Answer 3

4.

Question 4

Which of the following statements regarding membrane potentials is TRUE?

1. The potential difference between two points in the extracellular space is zero.
2. When cations leave a cell the inside of the cells becomes more positive.
3. When anions leave the cell the inside of the cell becomes more negative.

Answer 4

1 Only

Question 5

In the model shown below the membrane-spanning protein is an anion-selective channel. Which of the following will happen when this channel opens?

1. X+ will enter the cell
2. Y- ions will leave the cell
3. the inside of the cell will become more positive
4. the inside of the cell will become more negative
5. cations will leave the cell

Answer 5

the inside of the cell will become more negative

Question 6

In the model system illustrated below the membrane-spanning protein is a cation-selective channel. When this ion channel opens which of the following will happen?

1. the inside of the cell will become more negative
2. none of these statements describe what will happen
3. anions will flow into the cell
4. Y- will flow out of the cell
5. cations will flow out of the cell

Answer 6

2. none of these statements describe what will happen