Transport across membranes


What are the two main components of cell membranes?


A glucose molecule diffuses out of a cell through the selectively permeable cell membrane. What is this an example of?


The diagram shows three animal cells. Pairs of red circles represent oxygen molecules.

Three animal cells. Cell 1 has 6 pairs of oxygen molecules. Cell 2 has 7 pairs of oxygen molecules and cell 3 has 4 pairs of oxygen molecules.

Between which two cells is there the highest oxygen concentration gradient?


The diagram shows three plant cells and the solute concentrations of their cell solutions.

Three plant cells.  Cell 1 has a solute concentration of 0.8%, cell 2 has a solute concentration of 0.7% and cell 3 has a solute concentration of 0.6%

Between which cells will the movement of water by osmosis occur?


What may happen to red blood cells placed in distilled (pure) water?


Which structure can prevent a plant cell from bursting when it gains water by osmosis?


What will happen when plant cells are placed in distilled (pure) water?


The diagram shows a cube of potato, (P), in a beaker containing a solution containing a very high sugar concentration (R)

A beaker filled with a concentrated sugar solution - R.  A cube of potato - P - is in the beaker.

After one hour, what will have happened to cube P?


What could cause a plant cell to become plasmolysed?


Which of the following processes requires energy to occur?