Here's why:

* Organism: A single living thing, like a plant, animal, fungus, or bacteria. It's the most basic unit of life and can carry out all the necessary life functions on its own.

Let's look at the hierarchy of organization in an environment:

1. Individual organism: The starting point.

2. Population: A group of individuals of the same species living in the same area.

3. Community: All the different populations of species that live and interact in a particular area.

4. Ecosystem: A community of living organisms and their non-living environment, interacting as a system.

5. Biome: A large-scale ecosystem characterized by specific climate and dominant plant and animal life.

6. Biosphere: The entire part of the Earth where life exists, including all biomes.

So, while there are smaller components within an organism (like cells, tissues, and organs), they are not considered separate levels of organization in the environment itself.