Free online course Introduction to Biology

About the free online course

Biology is the science of life, but it only feels overwhelming when the basics are shaky. This free online course helps you build a clear, connected understanding of the living world by starting with the big questions: what biology studies, what makes something alive, and how scientists organize organisms through classification. From there, you’ll develop the core language needed to make sense of later topics in school and beyond, whether you’re preparing for exams, returning to study, or simply curious about how life works.

You’ll strengthen your foundation in the chemistry that powers living systems, including atoms, molecules, and the differences between ways of representing compounds. That base quickly becomes practical as you move into cell chemistry and the major organic molecules that keep organisms functioning. Instead of memorizing definitions in isolation, you’ll connect structure to function: why certain molecules store energy, how proteins support biological processes, and how enzymes speed up reactions so cells can survive.

As the course progresses, you’ll explore the cell as the basic unit of life, learning how key parts such as the membrane contribute to transport, protection, and communication. You’ll also make sense of how cells reproduce and pass on information by contrasting binary fission with the eukaryotic cell cycle, then following the logic of mitosis and meiosis and what each process is designed to accomplish.

To tie everything together, you’ll trace energy through life: how cells capture energy through glycolysis and the citric acid cycle, and how plants and other organisms transform light into chemical energy through photosynthesis and the Calvin cycle. You’ll also get an introduction to cell signaling, helping you understand how cells coordinate actions within tissues and respond to their environment. Short exercises along the way let you check your understanding and build confidence step by step.