Memory Levels of organization LTVersion en ligne Find the pairs. par Laura Quiroga Sánchez Cell: Basic unit of structure and function in an organism. Organ system: Group of one or more Organs working together to perform functions for the organism. Organism: Entire living thing that carries out all basic life functions. Tissue: Made of several cells similar in structure and function that work together to perform a specific job. Organ: Made of similar tissues that work together to perform a specific activity or job.