Cellupedia has some great information about the cell structures. A main objective of this site is to be a comprehensive and fun reference about cells. (
http://library.thinkquest.org/C004535/cell_membranes.html
)
A colourful animated representation of the cell membrane is shown. (
http://www.tamu.edu/classes/bich/mullins/bich410/olprg/10-2a_FluidMosaic/FluidMosaic.htm
)
Take a look at the movement of water across a cell to understand the meaning of hypertonic solutions, hypotonic solutions, and isotonic solutions. (
http://www.tvdsb.on.ca/westmin/science/sbi3a1/Cells/Osmosis.htm
)
Information provided explains how diffusion across a membrane works. Definitions of the related terms are also provided. (
http://www.biologycorner.com/bio1/diffusion.html
)
You will find the processes of both active transport and passive transport across a cell membrane shown in the form animations. (
http://www.northland.cc.mn.us/biology/Biology1111/animations/transport1.html
)