Tissue is composed of a group of similar cells that work together to carry out a particular job. Muscle tissue, the lining of the intestines and lungs, and xylem are examples of living tissues made up of similar cells working together.
Multicellular organisms are organized from least complex to the most complex. The order goes from cells, tissues, organs and organ systems to the organism. The tissues are made of similar cells. Organs are made up of a group of different tissues that work together to do a job. A group of different organs that work together to do a job is an organ system. Examples of systems include the circulatory system, the respiratory system, the digestive system, the nervous system and the reproductive system.