A general biology site – click on articles for brief introductions to many A level topics (recent ones include lipids, carbohydrates etc.). There are also discussion forums and links arranged by topic area
Site for this syllabus, includes full notes, summaries and exam questions
US college textbook site – has interactive tutorials on various A level topics.
Health site (US) including multimedia virtual labs (cardiology / Elisa); animations (heart, bacteria, movement across membranes); click and learn (antibiotics, membranes, circulation, ECG); virtual museum (cardiology, senses)
Animations of various biological processes – colourful and easy to understand
Interactive tutorials, particularly on genetics and biochemistry