An online journal with articles and practical protocols on biotechnology
A science information site – lots of biology topics are covered.
Clearly explained notes on here for introductory topics such as cells, diffusion and enzymes.
Series of Youtube vids on Biology topics, 40 here at present including cell biology, biochemistry, genetics, nervous system, etc. etc.
A US textbook site with interactive tutorials, animations and quizzes on many biology topics
Futurelearn brings together free online courses from many different universities. You may find something interesting here to increase your knowledge of A level biology subject areas or to help with an EPQ.