Organism
The basic level of ecological studies is concerned with the individual organism. Understanding how individual organisms interact with their environment is essential in ecology. Organisms are the fundamental units of ecology, and studying their behaviors, adaptations, and interactions with their surroundings provides valuable insights into the functioning of ecosystems.

Population
Once we understand the individual organism, the next level of ecological study involves populations of the same species. A population consists of a group of individuals of the same species living in a particular area. By studying populations, ecologists can analyze factors such as population size, density, distribution, and dynamics over time. This helps in understanding the mechanisms that regulate population growth and the impact of external factors on population dynamics.

Communities
Moving up the ecological hierarchy, communities are the next level of study. A community consists of multiple populations of different species living and interacting in the same area. Ecologists study the composition, diversity, interactions, and structure of communities to understand the complex relationships between different species and their influence on ecosystem functioning.

Biomes
At a broader scale, ecologists study biomes, which are large geographical areas characterized by distinct climate, vegetation, and animal life. Biomes encompass multiple communities and ecosystems, providing a holistic view of the global distribution of ecosystems. Understanding biomes is crucial for conservation efforts, as different biomes support unique biodiversity and provide essential ecosystem services.
In conclusion, while all levels of ecological studies are interconnected, the basic level starts with the study of individual organisms and gradually progresses to populations, communities, and biomes. Each level provides valuable insights into the complex interactions within ecosystems and helps in understanding the dynamics of the natural world.