DP Biology (first assessment 2025)

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Question SPM.2.HL.TZ0.b

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Date May Specimen-2023 Marks available [Maximum mark: 4] Reference code SPM.2.HL.TZ0.b
Level HL Paper 2 Time zone TZ0
Command term Outline Question number b Adapted from N/A
b.
[Maximum mark: 4]
SPM.2.HL.TZ0.b

Outline the role of membrane proteins in the movement of specific ions at specific times in the transmission of nerve impulses.

[4]

Markscheme
  1.  (during depolarization) Na+ channels open;
  2.  allowing Na+ to flow into the axon;
  3.  (during repolarization) K+ channels open;
  4.  allowing K+ to flow out of the axon;
  5.  the Na+/K+ pump returns the (axon) membrane to the resting potential;
  6.  by moving 3Na+ out and 2K+ in;

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