The movement of which ion out of the cell through leakage channels establishes the negative membrane potential?

• A. chloride
• B. potassium
• C. calcium
• D. sodium

Answer: (B)

Verified step by step guidance

1. Understand the concept of membrane potential: The membrane potential is the electrical potential difference across a cell's plasma membrane, primarily established by the distribution of ions.
2. Identify the role of ions in establishing membrane potential: Different ions contribute to the membrane potential, including sodium (Na⁺), potassium (K⁺), calcium (Ca²⁺), and chloride (Cl⁻).
3. Focus on potassium ions (K⁺): Potassium ions play a crucial role in establishing the negative membrane potential. They move out of the cell through leakage channels, which are always open, allowing K⁺ to diffuse down its concentration gradient.
4. Explain the effect of potassium ion movement: As K⁺ ions move out of the cell, they leave behind negatively charged proteins and other ions, contributing to a negative charge inside the cell relative to the outside.
5. Summarize the process: The movement of potassium ions out of the cell through leakage channels is the primary factor in establishing the negative membrane potential, as it creates an imbalance in charge across the membrane.