Moving up the hierarchy, cells organize into tissues, which form organs, and then organ systems. These systems work together to create individual organisms. At higher levels, organisms of the same species form populations, which interact with other species in communities. These communities, along with their physical environment, constitute ecosystems. The highest level, the biosphere, encompasses all life on Earth and its interactions with the physical environment. This hierarchical view of life not only aids in understanding biological complexity but also highlights the interconnectedness of all living systems.