Which of the following ions is most likely to cross the plasma membrane of a resting neuron? A) K⁺ B) Na⁺ C) Ca²⁺ D) Cl^-

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K⁺ is the ion that is most likely to cross the plasma membrane of a resting neuron because it is positively charged and is attracted to the negatively charged interior of the cell. Additionally, the resting membrane potential of neurons is predominantly determined by the concentration gradient of K⁺ ions, meaning that K⁺ is always more concentrated inside the cell than outside, which creates a driving force for the ion to move out of the cell. Na⁺ and Ca2+ ions are also positively charged, but they are less likely to cross the plasma membrane of a resting neuron because they are less concentrated inside the cell and because the membrane has lower permeability to these ions. Cl- ions are negatively charged and are repelled by the negatively charged interior of the cell, making them less likely to cross the membrane.

Which of the Following Ions Is Most Likely to Cross