IBBiologyHLExam QuestionsForm & FunctionMembranes & Membrane Transport

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First teaching 2023

First exams 2025

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Membranes & Membrane Transport (HL IB Biology)

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Membranes & Membrane Transport

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1
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Which row correctly identifies the components of a cell surface membrane?

Cell membrane structure MCQ

  Cholesterol Glycoprotein Glycolipid Protein Phospholipid
A. 3 2 4 1 5
B. 5 3 2 4 1
C. 1 4 2 3 5
D. 5 2 4 3 1

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    2
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    What is the main function of cholesterol in the cell surface membrane?

    • To provide hydrophilic channels

    • To regulate membrane fluidity

    • To assist active transport

    • To assist cell adhesion

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    3
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    Which of the following correctly describes the model of membrane structure that is now widely accepted?

    • A phospholipid bilayer with a series of proteins that are free to move around within the membrane

    • A phospholipid bilayer

    • A phospholipid bilayer with a layer of protein on either side

    • A phospholipid bilayer with a series of proteins in fixed positions throughout

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    4
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    Which of the statements about membrane fluidity is correct?

    • The higher the proportion of unsaturated fatty acid tails in a membrane, the higher the membrane fluidity

    • Cholesterol can restrict the motion of the molecules in a membrane, increasing membrane fluidity

    • Cells do not need to regulate membrane fluidity

    • The lower the proportion of unsaturated fatty acid tails in a membrane, the higher the membrane fluidity

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    5
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    Which of the following modes of transport is not an example of active or bulk transport?

    • Water moving through a partially permeable membrane

    • Phagocytosis of a pathogen

    • Exocytosis

    • Endocytosis

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    11 mark

    The sentence below describes a cellular process and an associated eukaryotic cellular structure.

     Cells which have a high rate of …I… will have many ...II… .

     Select the terms that best fit the gaps in this sentence.

      I II
    A. Facilitated diffusion Mitochondria
    B. DNA replication Lysosomes
    C. Exocytosis Vesicles
    D. Phospholipid production Ribosomes

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      21 mark

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

        Influences membrane fluidity Acts as a receptor site for hormones Binds to neurotransmitters
      A. Glycolipids and glycoproteins Cholesterol Proteins and glycolipids
      B. Glycoproteins Glycolipids and glycoproteins Cholesterol
      C. Cholesterol Proteins and glycoproteins Glycoproteins
      D. Phospholipids and cholesterol Proteins and glycolipids Phospholipids and cholesterol

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        31 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 affected in cystic fibrosis?

        • Cholesterol 

        • Proteins

        • Glycolipids

        • Phospholipids 

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        41 mark

        A student sketches a section of a cell surface membrane to show the fluid mosaic model.

        A0FRwq67_q5-1-3-cell-membrane-medium-ib-hl-biology

        How would they correctly label their sketch?

          W X Y Z
        A. Integral protein Peripheral protein Phospholipid Glycoprotein
        B. Peripheral protein Integral protein Glycoprotein Phospholipid
        C. Glycoprotein Peripheral protein Integral protein Phospholipid
        D. Integral protein Integral protein Glycoprotein Phospholipid

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          51 mark

          Select the table row that correctly completes the following sentence:

          Cholesterol is a component of animal cell membranes. Most of a cholesterol molecule is ...I… . This means that cholesterol ...II… 

            I II
          A. ...hydrophobic, so it is attracted to the hydrocarbon tails at the centre of the membrane. ...reduces the fluidity of the membrane and reduces its permeability to particles such as sodium ions and hydrogen ions.
          B. ...hydrophilic, so it is attracted to the hydrocarbon tails at the centre of the membrane. ...increases the fluidity of the membrane and reduces its permeability to particles such as sodium ions and hydrogen ions.
          C. ...hydrophobic, so it is attracted to the hydrocarbon tails at the centre of the membrane. ...reduces the fluidity of the membrane and increases its permeability to particles such as sodium ions and hydrogen ions
          D. ...hydrophilic, so it is attracted to the phosphate heads on the periphery of the membrane. ...increases the fluidity of the membrane and increases its permeability to particles such as sodium ions and hydrogen ions.

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            61 mark

            The Davson-Danielli model of cell membrane structure stated that cell membranes consisted of a phospholipid bilayer sandwiched between two layers of protein.

            Which piece of evidence would have contributed to the falsification of the Davson-Danielli model and the acceptance of the fluid mosaic model?

            • The presence and positioning of globular peripheral and integral proteins

            • The amphipathic properties of phospholipids

            • The presence of a hydrophobic region on the surface of the membrane

            • The orientation of the hydrophobic phospholipid tails away from the proteins

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            71 mark

            What is the difference between simple diffusion and facilitated diffusion?

              Simple diffusion Facilitated diffusion
            A. Diffusion rate inversely proportional to concentration gradient Diffusion rate proportional to concentration gradient
            B. Never involves a membrane Always involves a membrane
            C. Occurs across any part of a membrane Occurs via channels in the membrane
            D. A passive process that does not require energy from ATP An active process that requires energy from ATP

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              1
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              Signalling molecules are used to transfer information around the body. Once at the target cell there are different ways in which different types of signalling molecule cause a response.

              Which of the following is able to enter a cell directly through the phospholipid bilayer to cause a response, without the need for membrane proteins?

              • Lipid-based hormones

              • Protein-based hormones

              • Neurotransmitters

              • Charged molecules

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              2
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              Proteins in the cell surface membranes of mouse cells and human cells were labelled with different coloured dyes.

              When a cell from each species was fused together, the different-coloured labels were first found in different regions of the hybrid cell’s cell surface membrane. After 40 minutes, the labels were evenly distributed around the entire cell surface membrane. This is shown in the diagram below.

              1-3-h-q2-paper-1 

              Which of the following correctly explains this observation?

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

              • Only the 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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              3
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              Membranes in cells include the following components:

              1. Cholesterol
              2. Glycoproteins
              3. Phospholipids
              4. Proteins

              Which row of the table shows the correct function of each component? 

                Stabilising the hydrophobic layer Recognising self / non-self Limiting movement of water Transporting ions through membranes
              A. 1 2 3 4
              B. 3 1 2 4
              C. 1 3 1 2
              D. 4 3 4 2

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                4
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                The graph shows how the concentration of a substance affects its rate of absorption into a cell.

                1-3-h-q5-paper-1

                Substance X enters by simple diffusion and substance Y by facilitated diffusion. 

                Why does the curve for substance Y plateau above a certain concentration?

                • ATP production rate reaches a maximum level

                • The concentration of Y reaches equilibrium on each side of the membrane

                • Carrier proteins are saturated

                • The membrane because impermeable to Y at a certain concentration

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