Class 11 Biology chapter 8 notes discuss it as follows,

An organism is made up of multiple organ systems that work together. Each organ system includes a number of organs, such as the neurological system, digestive system, circulatory system, and so on. And several types of tissues combine to make these organs. A tissue is made up of cells that are interconnected and fulfill a common purpose. Because a cell can perform all of the functions of an organism, it is known as the basic building unit of all living things.