Lesson 3.2.3.1

3.2.3.1 Membrane structure and the fluid mosaic Quiz: AQA Biology, Unit 2

20 questions

Written by Revision Ninja · Last reviewed 11 October 2026

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Lesson 3.2.3.1, Membrane structure and the fluid mosaic: 20 multiple choice questions for the AQA Biology (7402), Unit 2: Cells, written with Revision Ninja.

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The 20 questions

  1. Which molecules form the basic phospholipid bilayer of a cell membrane?

    • Phospholipids arranged with hydrophilic heads outside and hydrophobic tails inside.
    • Cellulose fibres arranged in parallel layers across the membrane.
    • Proteins forming a continuous sheet with lipids packed inside them.
    • Phospholipids arranged with hydrophobic heads outside and hydrophilic tails inside.

  2. Which statement describes the fluid mosaic model of membrane structure?

    • A cellulose wall surrounding a single layer of fixed phospholipids.
    • A rigid double sheet of proteins with no lipid molecules present.
    • A phospholipid bilayer with proteins and other molecules that can move laterally within it.
    • A solid layer of cholesterol with all proteins fixed in one position.

  3. Which molecules in the cell membrane have carbohydrate chains attached to them?

    • Mitochondrial DNA and ribosomes
    • Channel proteins and carrier proteins
    • Glycoproteins and glycolipids
    • Cholesterol and phospholipids

  4. What is the role of cholesterol in cell membranes?

    • It restricts the movement of other molecules making up the membrane.
    • It transports sodium ions across the membrane using ATP.
    • It forms the channels through which water passes by osmosis.
    • It hydrolyses ATP to release energy for active transport.

  5. Membranes around eukaryotic organelles and the cell surface membrane are described as having what basic structure?

    • The same basic structure.
    • A structure with no phospholipid at all.
    • A structure made only of cellulose and starch.
    • Completely different structures with no shared components.

  6. Which molecule is most likely to be a channel protein in a cell surface membrane?

    • A protein that binds glucose and changes shape to move it across.
    • A carbohydrate chain attached to the outside of a phospholipid.
    • A protein that forms a water-filled pore allowing specific ions through.
    • A lipid molecule that moves freely within the bilayer without a pore.

  7. Which property of phospholipids explains why simple diffusion of large polar molecules is limited across the membrane?

    • The hydrophilic heads repel all ions and allow only gases through.
    • The ATP molecules bound to the membrane prevent diffusion of all substances.
    • The cellulose layer blocks any molecule larger than a glucose molecule.
    • The hydrophobic tails form a barrier that repels polar molecules.

  8. Which feature of the membrane is involved in cell recognition by the immune system?

    • Cholesterol embedded in the inner hydrophobic core.
    • Ribosomes attached to the inner face of the membrane.
    • Glycoproteins on the outer surface of the membrane.
    • Cellulose microfibrils arranged across the outer surface.

  9. A student observes that a membrane becomes less fluid at low temperatures. Which component is most likely to explain this?

    • Glycogen, which stores energy and is hydrolysed at low temperature.
    • Cellulose, which becomes rigid and forms the cell wall.
    • Cholesterol, which restricts movement of the other membrane molecules.
    • Starch, which is digested into maltose by amylase in the membrane.

  10. A membrane is formed by 2000 phospholipid molecules. Which feature of the bilayer explains why water-soluble molecules cannot easily cross it?

    • The membrane is made of cellulose, which does not allow any ion to pass.
    • The fatty acid tails are hydrophobic, so polar molecules cannot dissolve through the core.
    • The phosphate heads are hydrophobic and seal the membrane against water.
    • The membrane contains only proteins, which are too large to allow diffusion.

  11. Which of these is a function of glycolipids in the membrane?

    • Breaking down ATP to release energy for active transport.
    • Synthesising proteins from amino acids on the surface.
    • Forming the hydrophobic channels for water movement by osmosis.
    • Acting as cell-surface recognition molecules.

  12. In the fluid mosaic model, why are proteins described as a mosaic?

    • They are found only inside the cytoplasm and not in the membrane.
    • They are scattered within the lipid bilayer in a pattern that varies across the surface.
    • They are all arranged in identical rows that never change position.
    • They form a continuous, fixed layer over the outer surface of the bilayer.

  13. A red blood cell membrane is placed in a solvent that dissolves lipids. Which molecules would be most rapidly removed?

    • Water and sodium ions, which are inorganic substances.
    • Cellulose and starch, which are carbohydrate polymers.
    • Phospholipids and cholesterol, which are lipids.
    • Glucose and amino acids, which are sugars and proteins.

  14. A membrane has a higher proportion of channel proteins and carrier proteins in one region than another. What does this indicate about its transport rate?

    • Transport through that region stops, because proteins can only move by osmosis.
    • Transport through that region is slower, because more proteins block the membrane.
    • Transport through that region is likely to be faster, if other conditions are equal.
    • Transport through that region is unchanged, because proteins do not affect movement.

  15. Which molecules in the membrane are described as making up the fluid mosaic together?

    • Cellulose, starch, glycogen and chitin.
    • Amino acids, nucleotides, glucose and ATP.
    • DNA, RNA, ribosomes and histone proteins.
    • Phospholipids, proteins, glycoproteins, glycolipids and cholesterol.

  16. A cell surface membrane has a high number of folds in the membrane for absorbing nutrients. What is the main effect on transport?

    • It decreases surface area, so the rate of transport across the membrane decreases.
    • It has no effect because surface area does not change the rate of transport.
    • It changes the phospholipid molecules into proteins to speed transport.
    • It increases surface area, so the rate of transport across the membrane increases.

  17. Which statement best explains why the membrane is described as selectively permeable?

    • All substances pass through freely, because the bilayer has no barrier.
    • No substance can pass, because the membrane is made of solid protein.
    • Only gases can pass, because all other molecules are blocked by cellulose.
    • Only some substances pass through, depending on size, polarity and transport proteins.

  18. Why is the phospholipid bilayer described as fluid rather than rigid?

    • The membrane is solid only at temperatures above 37 degrees Celsius, so it flows when heated.
    • Phospholipids are fixed by covalent bonds to the cell wall in every plant cell.
    • Phospholipids can move sideways within their layer, and proteins can drift laterally within it.
    • The layer is made of cellulose, which bends easily under pressure from the cytoplasm.

  19. Which molecule in a membrane is most likely to act as a receptor for a hormone?

    • A membrane protein with a specific binding site that changes shape when the hormone binds.
    • A cholesterol molecule that dissolves the hormone within the hydrophobic bilayer core.
    • A cellulose microfibril that transports the hormone inward across the membrane surface.
    • A phospholipid tail that stores the hormone until it is released into the cytoplasm.

  20. Which term describes proteins that extend through the whole phospholipid bilayer?

    • Histone proteins
    • Integral (transmembrane) proteins
    • Cellulose microfibrils
    • Ribosomal RNA molecules

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