Biology4Kids A great source for simple explanations of terms, it contains good simple drawings of cell organelles and their functions.

Chem4kids A good basic discussion of atoms, compounds, and molecules. This site discusses bond types using easy to understand illustrations. It has a good basic discussion of biochemical families and how they are made.

Excell at Cells The site might seem to be a little simple for high school kids, but has good explanations of difficult concepts.

Tours of the Cell A very good site. It contains great microphotographs of different kinds of cells. Make sure you use the practice tests to prepare for the real thing.

Cell Biology Look a the structure of prokaryotes, eukaryotes and virus; this is a very good review site.

Biology HyperText- Harvard University May be too much information, but it has very good illustrations of organelles. This site contains very helpful, but intense explanations of cell functions.

CellsAlive! Contains outstanding microphotographs of cells, organelles, mitotic phases. This site has very good animations and clear explanations of events and structures. Make sure you take the practice quizzes.

Microscopes A college lab site for introductory biology course. A good review of the material.

Mitosis Tutorial Shows the stages of mitosis in a plant cell.

Mitosis An animation of the stages of mitosis in an animal cell