Cell Biology: Cells are the basic unit of life. Prokaryotic cells (bacteria) lack a nucleus and membrane-bound organelles, while eukaryotic cells (plants, animals) have a nucleus and organelles. Diffusion is the movement of particles from high concentration to low concentration, while osmosis is the movement of water across a membrane. Mitosis is the process of cell division in which two identical daughter cells are produced. Organisation: Tissues are made up of cells with similar functions. Organs are made up of different tissues working together. Organ systems are made up of organs working together. Plants have a root system, shoot system, and reproductive system. Infection and Response: The immune system defends the body against pathogens. White blood cells, such as phagocytes and lymphocytes, play a key role in the immune response. Vaccines c ...