2.1 Principles of Organisation

^{(taken straight from spec)}
- Cells are the basic building blocks of all living organisms.
- A tissue is a group of cells with a similar structure and function.
- Organs are aggregations of tissues performing specific functions.
- Organs are organised into organ systems, which work together to form organisms.
- Cell < Tissue < Organ < Organ System < Organism
- (that is literally it for an entire topic wth)