Although Na⁺ is smaller than K⁺, its passage through the K⁺ channel is blocked by the _______ filter.

Question

Quizplus · Accepted Answer

The sentence is discussing the passage of Na⁺ through the K⁺ channel. Therefore, the missing word must describe something about the channel that blocks the passage. The phrases "negativity" and "positivity" do not make sense in this context. However, "selectivity" makes sense as an explanation for a channel blocking certain molecules or ions. Therefore, the best choice is D. As for the other choices, CO₂ is not a known filter or term in this context, so A is incorrect.

Although Na+ Is Smaller Than K+, Its Passage Through the K+

Although Na⁺ Is Smaller Than K⁺, Its Passage Through the K⁺