Membrane transport

Nature of science

• Experimental design—accurate quantitative measurement in osmosis experiments are essential. (3.1)

Understandings

• Particles move across membranes by simple diffusion, facilitated diffusion, osmosis and active transport.

• The fluidity of membranes allows materials to be taken into cells by endocytosis or released by exocytosis. Vesicles move materials within cells.

Applications

• Structure and function of sodium–potassium pumps for active transport and potassium channels for facilitated diffusion in axons.

• Tissues or organs to be used in medical procedures must be bathed in a solution with the same osmolarity as the cytoplasm to prevent osmosis.

Skills

• Estimation of osmolarity in tissues by bathing samples in hypotonic and hypertonic solutions. (Practical 2)

DBQs

DBQ 36

DBQ 39

DBQ 42