Q BankQuestion BankDocsDocuments

B2.1.12 (HL)—Cholesterol and fluidity

Cholesterol sits among phospholipids in animal membranes and regulates fluidity, permeability, and resistance to temperature-driven stiffness or disorder; Its effect depends on temperature and the physical packing of nearby phospholipids.

Syllabus
First assessment 2025
Objective
B2.1.12
Level
HL

Exam analysis

Chance of appearing5%of analysed past papers
Latest appearanceMay 2025
Most common paperPaper1
Typical marks1

Common command terms

  • Identify
  • State
  • Outline

Scoring notes

Common mistake
Giving only a vague stabilizing role without mentioning fluidity or permeability.

Recent exam appearances

May 2025Paper2 ["HL"] · TZ23(d)[ 1 ]B2.1.12 (HL)—Cholesterol and fluidity
November 2023Paper1 ["HL"] · TZ22[ 1 ]B2.1.12 (HL)—Cholesterol and fluidity
May 2022Paper1 ["HL"] · TZ12[ 1 ]B2.1.12 (HL)—Cholesterol and fluidity
May 2021Paper1 ["HL"] · TZ16[ 1 ]B2.1.12 (HL)—Cholesterol and fluidity
November 2020Paper2 ["HL"] · TZ02(a)(ii)[ 1 ]B2.1.12 (HL)—Cholesterol and fluidity
Practice this objective

Coverage 2018–2025 · Updated 15 Jul 2026

Concept essentials

  • Cholesterol regulates fluidity in animal cell membranes.
  • Cholesterol can reduce membrane permeability to some substances.
  • At high temperatures cholesterol helps prevent excessive membrane fluidity.
  • At low temperatures cholesterol helps prevent phospholipid packing from making membranes too stiff.
ConceptIB Biology HL