IB Biology SL B2.1.8 Selectivity in Permeability Questions

Distinguish direct phospholipid diffusion from protein-mediated facilitated diffusion and choose the correct route from polarity, size and gradient evidence in IB Biology SL B2.1.8.

Exam points

Distinguish simple diffusion directly through phospholipids from facilitated diffusion through selective membrane proteins.
Explain that both routes are passive and move particles down a concentration gradient, while polarity, size and membrane proteins determine permeability.
Use paired molecule or transport-data examples to choose simple diffusion or facilitated diffusion as the appropriate membrane route.

[Maximum number: 1]

Which molecule is paired with the component of the cell membrane that allows it to pass through the membrane?

Molecule

Component of the
cell membrane

insulin

aquaporin

glycogen

channel protein

oestradiol

phospholipid bilayer

carbon dioxide

pump protein

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IB Biology SL B2.1.8 Selectivity in Permeability Questions question 1