A LevelBiologyCIEExam Questions4. Cell Membranes & Transport4.1 Fluid Mosaic Membranes

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First teaching 2023

First exams 2025

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Fluid Mosaic Membranes (CIE A Level Biology)

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4.1 Fluid Mosaic Membranes

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4.1 Fluid Mosaic Membranes

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11 mark

Which row correctly labels this diagram of a cell surface membrane?iIhZF4Wb_q-4-1

  cholesterol glycoprotein glycolipid protein phospholipid

A

B

C

D

3

5

1

5

2

3

4

2

4

2

2

4

1

4

3

3

5

1

5

1

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    21 mark

    Which molecules found in the cell surface membrane are involved in cell recognition?

    • proteins, glycoproteins, glycolipids

    • phospholipids, cholesterol, proteins

    • cholesterol, glycolipids, phospholipids

    • glycoproteins, proteins, phospholipids

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    31 mark

    Triglycerides and phospholipids include the following structures:

    1   glycerol linked to fatty acids    

    2   saturated fatty acid chains   

    3   hydrophobic fatty acid chains

    Which structures cause the cell surface membrane to form a phospholipid bilayer?

    • 1 and 2

    • 2 only

    • 2 and 3

    • 1, 2 and 3

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    41 mark

    The fluid mosaic model of membrane structure is shown in the diagram. 

    Which labelled structure enables a hormone to recognise its target cell?

    cie-ias-4-1

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      51 mark

      What is the function of cholesterol in the cell surface membrane?

      • to provide hydrophilic channels

      • to regulate membrane fluidity

      • to assist active transport

      • to assist facilitated diffusion

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      61 mark

      Which of the following statements about the fluid mosaic model of membrane is correct?

      • The more unsaturated the fatty acid tails of the phospholipid, the more fluid the membrane.

      • The higher the temperature, the less fluid the membrane.

      • The lower the temperature, the more fluid the membrane.

      • The less unsaturated the fatty acid tails of the phospholipid, the more fluid the membrane.

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      71 mark

      A section of a cell surface membrane is shown in the diagram below.qp-7-easy-4-1-fluids-mosaic-membrane-cie-ial-biology

      Why are the phospholipid molecules arranged as shown?

      • The tails are hydrophilic and point away from water molecules.

      • The tails are hydrophobic and point towards water molecules.

      • The heads are hydrophilic and point towards water molecules.

      • The heads are hydrophobic and point away from water molecules.

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      81 mark

      Which of the following decreases the fluidity of the cell surface membrane?

      1 double bonds between carbon atoms in the fatty acid chains
      2 cholesterol
      3 fatty acids having longer chains

      • 1 and 2

      • 2 only

      • 2 and 3

      • 3 only

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      91 mark

      A section of a cell surface membrane is shown in the diagram below and a molecule is labelled X.

      q9-cie-4-1

      What is molecule X made from?

      • amino acids

      • nucleotides

      • monosaccharides

      • fatty acids

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      101 mark

      If a membrane protein is temporarily attached to the membrane it is called ‘peripheral’. If it is permanently attached to the membrane it is called ‘integral’.

      Proteins can either be described as ‘intrinsic’, if they extend across the whole bilayer, or ‘extrinsic’ if they are found in only one side of the bilayer.

      What best describes a channel protein?

      • a peripheral intrinsic membrane protein

      • an integral intrinsic membrane protein

      • a peripheral extrinsic membrane protein

      • an integral extrinsic membrane protein

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      11 mark

      Which row correctly matches the molecules found in the cell surface membrane with their function? 

        form hydrogen bonds with water act as receptor sites for hormones recognise antibodies
      A proteins and glycolipids phospholipids and cholesterol cholesterol and proteins
      B cholesterol and proteins proteins and glycolipids phospholipids and cholesterol
      C glycolipids and glycoproteins glycolipids and glycoproteins glycolipids and glycoproteins
      D phospholipids and cholesterol cholesterol and proteins proteins and glycolipids

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        21 mark

        Cystic fibrosis causes a defect in the cell surface membrane of epithelial cells, disrupting the transport of chloride ions out of affected cells.

        Which membrane component is involved?

        • cholesterol

        • protein

        • glycolipid

        • phospholipid

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        31 mark

        A section of a cell surface membrane is shown in the diagram below.

        qp-3-medium-4-1-fluids-mosaic-membrane-cie-ial-biology

        What is the correct function for each of the structures labelled?

         

        regulates membrane fluidity

        		 forms hydrogen bonds with water to stabilise membrane transports ions and large polar molecules

        A

        B

        C

        D

        1

        3

        2

        1

        1

        2

        1

        2

        2

        1

        3

        2

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        41 mark

        An increase in which bond type will increase the fluidity of the cell surface membrane?

        • hydrogen

        • C – O – C

        • C – N

        • C = C

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        51 mark

        When an individual requires a blood transfusion it is important that their blood type is known. Humans have 4 different blood types and if the incorrect type is used it can lead to the body rejecting the new blood. 

        Which label shows the part of a molecule that is different on the cell surface membrane of red blood cells of different blood types? 

        qn-15

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          61 mark

          A section of a cell surface membrane is shown in the diagram below.

          qp-6-medium-4-1-fluids-mosaic-membrane-cie-ial-biology

          Four functions of a cell surface membrane are listed:

          1

          movement of fat-soluble molecules

          2

          gives the cell shape

          3

          cell recognition 

          4

          movement of ions

          Which molecule is correctly paired with its function?

          • W and 1

          • X and 2

          • Y and 3

          • Z and 4

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          71 mark

          A water-soluble signalling molecule binds to the cell surface membrane, causing the following processes to occur.

          1

          Enzyme catalysed reaction 

          2

          2nd messenger production

          3

          Protein receptor conformational change

          4

          G-protein activation

          What is the correct sequence of events in the cell signalling pathway?

          • 1 →2 →3 → 4

          • 3 → 4 → 1 → 2

          • 1 →2 → 4 → 3

          • 2 → 4 → 3 →1

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          81 mark

          Temperature affects the fluidity of the cell surface membrane. Single celled species that cannot internally control their temperature, such as bacteria and yeast, change the composition of their membrane to maintain membrane structure. 

          How could bacteria and yeast adapt to an environment with a low temperature?

          • Decrease the amount of intrinsic proteins

          • Decrease the amount of cholesterol

          • Increase the proportion of saturated phospholipids

          • Increase the proportion of unsaturated phospholipids

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          91 mark

          Which row correctly describes the hydrophobicity of cell surface membrane molecules?

            Interior of a transport protein Exterior of an intrinsic protein Carbohydrate chain on a glycolipid

          A

          B

          C

          D

          hydrophobic

          hydrophobic

          hydrophilic

          hydrophilic

          hydrophilic

          hydrophobic

          hydrophilic

          hydrophobic

          hydrophilic

          hydrophobic

          hydrophobic

          hydrophilic

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            101 mark

            Two cell surface membrane molecules are shown in the diagrams below. 

            Which part affects the fluidity of the membrane?

            screenshot-2023-05-05-222218

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              11 mark

              Signaling molecules are used to transfer information around the body. Once at the target cell there are different ways in which types of signaling molecules cause a response.

              Which of the following acts directly in the nucleus?

              • lipid-based hormones

              • protein-based hormones

              • neurotransmitters

              • charged molecules

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              21 mark

              Which of the following do cell surface membranes and membranes within cells have in common?

              • Both are stabilised by glycoproteins

              • Both allow intracellular transport

              • Both protect cells from the contents of lysosomes

              • Both have sites for enzyme attachment

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              31 mark

              Proteins in the cell surface membranes of mouse cells and human cells were labelled with green and red fluorescent dyes respectively.

              When a cell from each species is fused together, the green and red fluorescent labels are first found in different regions of the hybrid cell’s cell surface membrane. After 40 minutes, the labels are evenly distributed around the entire cell surface membrane.

              What explains this observation?

              • Groups of protein and phospholipid molecules in the cell surface membrane are attached to each other and move together.

              • Only protein molecules in the outer layer of the cell surface membrane can move freely between phospholipid molecules.

              • All protein molecules in the cell surface membrane are fixed to structures within the cell, but phospholipid molecules move freely between them.

              • Protein molecules in the outer layer of the cell surface membrane and those which span the bilayer can move freely between phospholipid molecules.

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              41 mark

              The diagram shows a section of a cell surface membrane.

              q24-4-1

              What is the correct function of molecules X, Y and Z?

                X Y Z
              A chemical receptor allow lipid soluble molecules to pass through control the fluidity of the membrane 
              B barrier to polar molecules stabilise the membrane antigen
              C antigen chemical receptor  allow lipid soluble molecules to pass through
              D stabilise the membrane control the fluidity of the membrane barrier to polar molecules

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              51 mark

              Membranes in cells include the following components.

              1

              cholesterol

              2

              glycoproteins

              3

              phospholipids

              4

              proteins

              What is the correct function of each component? 

                stabilising the hydrophobic layer recognising self / non self separating dissolved ions transporting ions through membranes

              A

              B

              C

              D

              1

              3

              1

              4

              2

              1

              3

              3

              3

              2

              1

              4

              4

              4

              2

              2

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                61 mark

                Which statement correctly describes the intermolecular interactions that drive the bilayer formation when phospholipids are added to water?

                • Phospholipids have a strong affinity for each other, causing them to self-assemble into a bilayer.

                • Disordered, free-floating phospholipids is less favorable than an order bilayer arrangement.

                • Lipids cause water to arrange in an ordered, unfavorable cage-like structure. Forcing lipids into a bilayer reduces this effect.

                • The strength of Van der Waals forces between phospholipids is maximised by bilayer formation.

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                71 mark

                Cell surface membranes and organelle cell membranes have different roles.

                The diagram enables the identification of specific cell organelles based on their membrane’s structure and function.

                screenshot-2023-05-06-152432

                Based on the information provided in the diagram, what is the correct outcome?

                  1 2 3 4 5 6
                A chloroplast  vesicle smooth ER rough ER nucleolus mitochondrion
                B nucleus rough ER vesicle smooth ER mitochondrion chloroplast
                C nucleolus rough ER vesicle smooth ER nucleus mitochondrion
                D nucleus smooth ER mitochondrion rough ER vesicle chloroplast

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                81 mark

                Cholesterol and temperature both affect the fluidity of cell surface membranes. 

                Which statement is correct about the effect of cholesterol at different temperatures? 

                • Cholesterol decreases fluidity at low temperatures and increases fluidity at high temperatures.

                • Cholesterol decreases fluidity at low temperatures and decreases fluidity at high temperatures.

                • Cholesterol increases fluidity at low temperatures and decreases fluidity at high temperatures.

                • Cholesterol increases fluidity at low temperatures and increases fluidity at high temperatures.

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                91 mark

                An experiment was undertaken to test the permeability of the plasma membrane and tonoplast of beetroot cells in various different chemicals. Vacuoles of beetroot cells carry a red pigment which cannot diffuse through their plasma membranes and tonoplasts to leave the cell.

                The beetroot was cut into equal 1 cm3 cubes before being washed under a tap for 15 seconds to remove pigment released from outer damaged cells. The cubes were then placed in the various solutions, all of which turned red. 

                The table below shows four possible behaviors of phospholipids and proteins in different solutions, which is correct?

                  solution protein denatures solution phospholipids dissolve

                A

                B

                C

                D

                ethanol

                50°C water

                ethanol

                dilute HCl

                ✓

                ✓

                ✓

                ✓

                dilute HCl

                ethanol

                50°C water

                dilute HCl

                ✓

                ✓

                ✓

                ✓

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                  101 mark

                  Epilepsy is a disorder of the central nervous system caused by the over-excitation of neurons. One cause of epilepsy is the inability for potassium ions to enter the cell.

                  What structural component of the cell membrane would be most likely to cause epilepsy if its structure was altered?

                  • hydrophobic protein

                  • hydrophilic protein

                  • hydrophilic carbohydrate chain

                  • unsaturated phospholipid chain

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