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B2.1.15 (HL)—Sodium-potassium pumps

Sodium-potassium pumps use ATP to export sodium and import potassium, maintaining ion gradients that support resting potentials; This exchange is central to nerve and muscle membrane recovery.

Syllabus
First assessment 2025
Objective
B2.1.15
Level
HL

Exam analysis

Chance of appearing5%of analysed past papers
Latest appearanceMay 2019
Most common paperPaper1
Typical marks1

Common command terms

  • Identify
  • Suggest
  • Analyse

Scoring notes

Common mistake
Reversing sodium and potassium movement across the membrane.

Recent exam appearances

May 2019Paper1 ["HL"] · TZ24[ 1 ]B2.1.15 (HL)—Sodium-potassium pumps
May 2018Paper1 ["HL"] · TZ24[ 1 ]B2.1.15 (HL)—Sodium-potassium pumps
November 2017Paper2 ["HL"] · TZ01(d)(ii)[ 1 ]B2.1.15 (HL)—Sodium-potassium pumps
November 2017Paper2 ["HL"] · TZ01(d)(i)[ 2 ]B2.1.15 (HL)—Sodium-potassium pumps
May 2016Paper1 ["HL"] · TZ016[ 1 ]B2.1.15 (HL)—Sodium-potassium pumps
Practice this objective

Coverage 2014–2019 · Updated 15 Jul 2026

Concept essentials

  • Sodium-potassium pumps use ATP for active transport.
  • Each pump cycle moves sodium out of the cell and potassium into the cell.
  • The maintained ion gradients support resting potentials and recovery after depolarization.
  • Pump concentration can affect how quickly excitable cells are ready for further activity.
ConceptIB Biology HL