Put these terms in order from least complex to most complex: organ system, tissue, cell, organ.

Cell, Tissue, Organ, Organ System

Hey there,
Cell--> tissue --> organ--> organ system 
Cell: Basic unit of life
Tissue: a group cells make a tissue
Organ: A group of tissue makes an organ
Organ System: A group of organs make an organ system

Hope this helps :))

~Top

All of them are man made