B2.1 Membranes and membrane transport questions for IB Biology

52 questions on Membranes and membrane transport, written by Augment in the style of IB exam papers. Six of them are below in full, to answer on paper.

  • IB Biology
  • Part of B Form and function
  • SL and HL

Questions by paper and level

SL and HL questions are for students at either level. HL only questions cover what only HL students study.

PaperSL and HLHL onlyAll
Paper 1A12921
Paper 1B527
Paper 2111324
Every paper282452

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Questions to try

Written by Augment in the style of IB exams, not past papers. Answer them on paper, then check each one against its markscheme with a free account.

Question 1 · BIO-00234Paper 1A · HL only · 1 mark

Cultured human cells were treated with a drug that prevents clathrin from binding to membranes. The rate of uptake of three substances was then measured and expressed as a percentage of the rate in untreated cells.

Substance taken up

Uptake rate / % of untreated cells

Transferrin (an iron-carrying protein)

9

Oxygen

101

Glucose

97

Which conclusion is best supported by these results?

  1. A

    Clathrin is needed for transport through channel and carrier proteins

  2. B

    The drug stops all transport across the plasma membrane

  3. C

    Transferrin enters the cells mainly in vesicles that form with a clathrin coat

  4. D

    Oxygen enters the cells by endocytosis

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Question 2 · BIO-00238Paper 1B · 9 marks

A fraction rich in lysosomes was prepared from liver cells. Equal samples were suspended in sucrose solutions of different concentrations for 15 minutes at 25 °C. The activity of acid phosphatase, a lysosomal enzyme, was then measured by adding its substrate to the medium. The substrate cannot cross the lysosome membrane, so only enzyme that has escaped from lysosomes is active (free activity). Total activity was measured in a separate sample after adding a detergent that dissolves all membranes. Five replicates were done at each concentration.

The graph shows the mean free activity as a percentage of total activity. Error bars show ± one standard deviation.

Line graph with error bars: free acid phosphatase activity falls from 88 % of total at 0.00 mol dm−3 sucrose to 51 % at 0.10, 16 % at 0.20 and levels off near 10 % at 0.25–0.30 mol dm−3.
  1. (a)

    State the independent variable in this investigation.

    1 mark

  2. (b)

    Suggest why free activity was expressed as a percentage of total activity.

    1 mark

  3. (c)

    Describe the effect of sucrose concentration on free activity.

    2 marks

  4. (d)

    Deduce whether there is a significant difference between the free activity at 0.25 mol dm-3 and at 0.30 mol dm-3.

    1 mark

  5. (e)

    Explain the high free activity in low sucrose concentrations.

    2 marks

  6. (f)

    Using the results, explain the advantage to a living cell of keeping hydrolytic enzymes inside lysosomes.

    2 marks

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Question 3 · BIO-00108Paper 2 · 15 marks

Biological molecules and structures are held together both by covalent bonds and by weaker interactions.

  1. (a)

    Outline how condensation reactions produce polymers, using nucleic acids and one other type of macromolecule as examples.

    4 marks

  2. (b)

    Explain how the structure of DNA is related to its functions.

    7 marks

  3. (c)

    Outline how hydrophobic and hydrophilic interactions lead to the formation of lipid bilayers in cell membranes.

    4 marks

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Question 4 · BIO-00649Paper 1A · 1 mark

Why do phospholipids form a bilayer when they are mixed with water?

  1. A

    The phosphate heads form covalent bonds with each other in water

  2. B

    The fatty acid tails form hydrogen bonds with water molecules

  3. C

    Each molecule has a hydrophilic head and hydrophobic tails, so the tails cluster together away from water

  4. D

    Phospholipids are entirely hydrophobic, so water molecules push them together into two layers

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Question 5 · BIO-00600Paper 1B · 8 marks

Researchers made artificial membranes consisting only of a phospholipid bilayer, with no proteins. They measured how quickly six substances diffused through the bilayer and expressed the results as permeability coefficients: the higher the coefficient, the faster the substance crosses the bilayer.

Substance

Description

Permeability coefficient / cm s-1

testosterone

steroid hormone

4.0 × 10-3

oestradiol

steroid hormone

2.0 × 10-3

glycerol

small polar molecule with three –OH groups

5.0 × 10-6

urea

small polar molecule

4.0 × 10-6

glucose

hexose sugar with five –OH groups

5.0 × 10-10

sodium ion (Na+)

positively charged ion

1.0 × 10-12

  1. (a)

    Identify the substance that crosses the bilayer most slowly.

    1 mark

  2. (b)

    Calculate how many times greater the permeability coefficient of oestradiol is than that of glucose.

    1 mark

  3. (c)

    Suggest why the researchers used membranes that contained no proteins.

    1 mark

  4. (d)

    Explain why testosterone and oestradiol have the highest permeability coefficients.

    2 marks

  5. (e)

    Explain the low permeability coefficients of glucose and sodium ions.

    2 marks

  6. (f)

    Glycerol and glucose are both polar. Suggest why glycerol crosses the bilayer much faster than glucose.

    1 mark

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Question 6 · BIO-00250Paper 2 · 15 marks

Eukaryotic cells are divided into compartments by membranes.

  1. (a)

    Describe the structure of the plasma membrane according to the fluid mosaic model.

    4 marks

  2. (b)

    Explain the advantages of compartmentalization in eukaryotic cells.

    7 marks

  3. (c)

    Outline how phagocytes help to control infections.

    4 marks

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The notes on B2.1 Membranes and membrane transport

More questions in Form and function

  1. B1.1Carbohydrates and lipids
  2. B1.2Proteins
  3. B2.1Membranes and membrane transportThis page
  4. B2.2Organelles and compartmentalisation
  5. B2.3Cell specialisation
  6. B3.1Gas exchange
  7. B3.2Transport
  8. B3.3Muscle and motilityHL only
  9. B4.1Adaptation to environment
  10. B4.2Ecological niches

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