[Campbell Biology P.269] Which of the following accurately describes the sequence of events ... | Practice Question

Which of the following accurately describes the sequence of events for a ligand-gated ion channel, as depicted in Figure 11.8?

  • A: Ligand binds to receptor → Channel closes → Ions enter cell.
  • B: Channel is closed → Ligand binds and channel opens → Ions flow in, triggering cellular response → Ligand dissociates and channel closes.
  • C: Ions flow into cell → Channel opens → Ligand binds to receptor.
  • D: Ligand dissociates → Channel opens → Ions flow out.

Explanation

Figure 11.8 clearly illustrates three sequential steps: 1 The channel is initially closed. 2 Ligand binds, causing the channel to open and ions to flow in, leading to a cellular response. 3 The ligand dissociates, and the channel closes, stopping ion flow. Option B accurately captures this entire sequence.