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B2.1.10—Fluid mosaic model

The fluid mosaic model describes a mobile phospholipid bilayer containing embedded proteins, surface proteins, cholesterol, and carbohydrate-bearing components; Evidence and diagrams emphasize both component positions and lateral mobility.

Syllabus
First assessment 2025
Objective
B2.1.10
Level
HL

Exam analysis

Chance of appearing5%of analysed past papers
Latest appearanceMay 2024
Most common paperPaper2
Typical marks1–3

Common command terms

  • Draw
  • Identify
  • Distinguish
  • State
  • Outline

Scoring notes

Common mistake
Drawing proteins only as external layers rather than embedded within the bilayer.

Recent exam appearances

May 2024Paper2 ["HL"] · TZ12(b)[ 1 ]B2.1.10—Fluid mosaic model
May 2023Paper1 ["HL"] · TZ22[ 1 ]B2.1.10—Fluid mosaic model
May 2018Paper2 ["HL"] · TZ16(a)[ 4 ]B2.1.10—Fluid mosaic model
November 2016Paper1 ["HL"] · TZ03[ 1 ]B2.1.10—Fluid mosaic model
May 2016Paper2 ["HL"] · TZ06(a)[ 3 ]B2.1.10—Fluid mosaic model
Practice this objective

Coverage 2014–2024 · Updated 15 Jul 2026

Concept essentials

  • The fluid mosaic model contains a phospholipid bilayer with mobile lipids and proteins.
  • Integral proteins are embedded in the bilayer, while peripheral proteins sit at membrane surfaces.
  • Cholesterol lies among phospholipid tails and carbohydrate chains project outward.
  • Freeze-fracture and model-comparison evidence support embedded proteins rather than a protein sandwich.
ConceptIB Biology HL