Final answer:
The most basic level of ecological organization is the individual, which is the simplest unit in the ecological hierarchy that ranges up to the biosphere.
Step-by-step explanation:
The most basic level of ecological organization is the individual. In ecology, levels of organization range from the individual organism to the biosphere. An individual is a single organism which is the basic unit of survival and reproduction. At higher levels, individuals of the same species living in the same area form a population. Various populations interact in a community, and communities interact with abiotic factors in an ecosystem. Together, ecosystems form a biome, and all the biomes on Earth make up the biosphere, which is the collection of all ecosystems on Earth where life exists.