Cambridge O Level Biology · Syllabus 5090 · Cells
Organ
What is Organ?
A structure made of several different tissues working together to perform a particular function. The heart is an organ because it contains cardiac muscle tissue, nervous tissue, blood vessels and epithelium, all serving the single function of pumping blood.
This definition is part of the Cells chapter in Cambridge O Level Biology.
Organ in context
A cell is the smallest structural and functional unit considered in this syllabus. Cell structures are not labels to be memorised in isolation: each one performs work that keeps the cell, and therefore the whole organism, alive. Topic 1 asks you to identify those structures in animal, plant and bacterial cells, to state what each one does, to obtain your own evidence with a light microscope, to record that evidence as a biological drawing, to convert between image size and actual size using magnification, and to explain how specialised cells are built into tissues, organs, organ systems and organisms.
Questions students ask about Organ
What is the difference between a tissue and an organ?
A tissue is a group of similar cells working together to perform a particular function; “many cells” is not enough, because the cells must be similar and must work together. An organ is a structure made of several different tissues working together for one function: the heart contains cardiac muscle, nervous tissue, blood vessels and epithelium, all serving the job of pumping blood. The full order is organelle → cell → tissue → organ → organ system → organism.