2.1: Principles of organisation
Not started yet — this one needs some love.
Cell → tissue → organ → organ system → organism: the hierarchy of organisation.
Tissue: group of cells with similar structure and function (e.g. muscle tissue, epithelial tissue).
Organ: aggregation of different tissues working together to perform a specific function (e.g. stomach contains muscle tissue, epithelial tissue, glandular tissue).
Organ system: group of organs working together for a major body function (e.g. digestive system, circulatory system).
Organism: complete living thing made up of multiple organ systems.
Common exam mistakes
A tissue is a group of cells with similar structure and function — saying 'a group of cells working together' without including 'similar structure' or 'similar function' is insufficient.
An organ is made of multiple different types of tissue — do not say an organ is just one tissue type.
The order is: cells → tissues → organs → organ systems — not the other way around.