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IB Biology SL B2.1.6 Channel Proteins Questions

Explain how hydrophilic channel pores let selected ions and polar solutes diffuse down gradients without ATP, using channel selectivity evidence in IB Biology SL B2.1.6.

Syllabus
First assessment 2025
Course
Biology SL
Level
SL

Exam points

  • Identify channel proteins as selective hydrophilic pores that allow facilitated diffusion of ions or polar solutes across a membrane.
  • Explain that facilitated diffusion through channels is passive movement down a concentration gradient without ATP.
  • Relate channel selectivity to the size, charge and polarity of the transported substance.

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Study B2.1.6—Channel proteins conceptsOpen the corresponding Concept lesson for explanations, examples and exam connections.

IB Biology SL B2.1.6 Channel Proteins Questions question 1

[Maximum number: 3]

The diagram (not to scale) shows a cell which contains water and sodium ions. This cell is immersed in a salt solution of water and sodium ions.

Figure for Question IB Biology SL B2.1.6 Channel Proteins Questions question 1 — IB Biology SL

Explain facilitated diffusion.

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