IB Biology SL B2.1 Membranes and Membrane Transport Questions

Practise IB Biology SL B2.1 by linking membrane structure and selective permeability to diffusion, osmosis, transport proteins and ATP-driven active transport.

Exam points

Identify amphipathic phospholipid bilayers, explain head–tail orientation in water and relate the hydrophobic core to selective barriers and compartment separation.
Define simple diffusion as passive net movement down a concentration gradient without ATP or transport proteins, including small non-polar molecules crossing the bilayer.
Distinguish integral and peripheral membrane proteins and identify their channel, pump, receptor, enzyme, adhesion and recognition roles.
Define osmosis, predict water movement from solute or water-potential differences and explain how aquaporins increase water permeability.
Explain facilitated diffusion through selective channel proteins as passive movement down a gradient, using size, charge and polarity to explain selectivity.
Explain active transport as ATP-powered movement against a concentration gradient using selective pump proteins.
Identify glycoproteins and glycolipids as membrane components carrying extracellular carbohydrate chains and relate them to cell recognition and adhesion.
Use the fluid mosaic model to locate hydrophilic heads, hydrophobic tails, integral proteins and mobile membrane components in a selective membrane.

Covered syllabus points

B2.1.1—Lipid bilayers as basis B2.1.2—Bilayers as barriers B2.1.3—Simple diffusion B2.1.4—Integral and peripheral proteins B2.1.5—Osmosis and aquaporins B2.1.6—Channel proteins B2.1.7—Pump proteins B2.1.8—Selectivity in permeability B2.1.9—Glycoproteins and glycolipids B2.1.10—Fluid mosaic model

[Maximum number: 3]

The diagram shows the stages of the cell cycle.

Explain the properties of phospholipids that allow bilayers to form in cell membranes.

[Maximum number: 4]

(a)

Outline how molecules move across a membrane by simple diffusion.

[ 2 ]

(b)

Explain the role of protein pumps in active transport.

[ 2 ]

[Maximum number: 2]

List two functions of membrane proteins.

[Maximum number: 2]

Outline how molecules move across a membrane by simple diffusion.

[Maximum number: 2]

Describe the movement of water across membranes.

[Maximum number: 3]

The diagram (not to scale) shows a cell which contains water and sodium ions. This cell is immersed in a salt solution of water and sodium ions.

Explain facilitated diffusion.

[Maximum number: 2]

Explain the role of protein pumps in active transport.

[Maximum number: 1]

Which molecule is paired with the component of the cell membrane that allows it to pass through the membrane?

Molecule

Component of the
cell membrane

insulin

aquaporin

glycogen

channel protein

oestradiol

phospholipid bilayer

carbon dioxide

pump protein

[Maximum number: 1]

Which part of the membrane allows cell recognition?

Three-dimensional membrane model with a lipid bilayer and embedded structures. A marks a branched outer chain, B a small molecule among the tails, C a circular head and D a spanning protein.

[Maximum number: 4]

Draw a labelled diagram to show the molecular structure of a membrane.

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Covered syllabus points

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