- Summary of biological macromolecules at Science Profile Online “What is organic chemistry?”
- “The four big building blocks of life” from the biology explainer (mostly text).
- “Biology molecules” from CrashCourse on YouTube (By Hank, that American with the annoying voice).
- This site has some great resources for revision of homeostasis: Human Biological Science 3A.
If you only check out two of these, make sure it is the first and last ones!