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CAIE A-Level Biology AS 4.1 Fluid Mosaic Membranes Questions

Practise CAIE AS Biology 4.1 by explaining membrane structure and component roles, then tracing how ligand binding at cell-surface receptors triggers a response.

Syllabus
2028–2030
Course
Biology 9700
Level
AS

Exam points

  • Explain hydrophilic heads, hydrophobic tails and protein movement in fluid-mosaic diagrams of the membrane.
  • Identify cholesterol, glycolipids and glycoproteins in membrane diagrams, including outward-facing carbohydrate chains.
  • Explain how phospholipid and cholesterol structures affect membrane fluidity, stability and permeability.
  • Relate channel, carrier, receptor and glycoprotein structures to transport, signalling and cell recognition.
  • Outline ligand signalling from secretion and transport to binding at a target-cell surface receptor and response.

Covered syllabus points

4.1.1—Fluid mosaic membrane model4.1.2—Membrane component arrangement4.1.3—Role of membrane components4.1.4—Cell signalling process

Question 1

[Maximum number: 1]

What causes the phosphate heads of phospholipids to become polar?

A

The phosphate heads are joined to water molecules by hydrogen bonds.

B

The phosphate heads are insoluble in water.

C

The phosphate heads become ionised in water.

D

The phosphate heads are joined to water molecules by covalent bonds.

Question 2

[Maximum number: 1]

Where in the cell surface membrane are the carbohydrate chains of glycoproteins and glycolipids mainly located?

glycoproteins

glycolipids

inner surface

inner surface

inner surface

outer surface

outer surface

inner surface

outer surface

outer surface

Question 3

[Maximum number: 1]

Which component of cell surface membranes helps to reduce fluidity of the phospholipids at high temperatures?

A

phosphate groups

B

unsaturated fatty acids

C

cholesterol

D

proteins

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