Question

question which of the following is true of transmembrane potential? select all that apply positive and negative charges are separated. it is measured in millivolts. the positive and negative ions are distributed equally across the membrane. changes can trigger muscle contraction.

Explanation:

1. For "Positive and negative charges are separated": Transmembrane potential (like resting membrane potential) arises due to separation of positive and negative charges across the cell membrane (e.g., more negative ions inside, positive outside in resting state), so this is true.
2. For "It is measured in millivolts": Transmembrane potential (e.g., resting membrane potential is around -70 mV) is indeed measured in millivolts, so this is true.
3. For "The positive and negative ions are distributed equally across the membrane": If ions were distributed equally, there would be no potential difference. The unequal distribution (e.g., Na⁺ outside, K⁺ and anions inside) creates the potential, so this is false.
4. For "Changes can trigger muscle contraction": In muscle cells, changes in transmembrane potential (action potentials) trigger the release of calcium and subsequent muscle contraction, so this is true.

Answer:

• Positive and negative charges are separated.
• It is measured in millivolts.
• Changes can trigger muscle contraction.