Ecosystem is:

An ecosystem is defined as a functional unit that includes the whole community in a given area interacting with the abiotic factors. It consists of both living organisms (biotic factors) and non-living components (abiotic factors) that interact with each other.

Explanation:

1. Definition of an ecosystem:
An ecosystem is a complex network of interactions between living organisms and their environment. It includes all the living organisms (plants, animals, microorganisms) in a specific area, as well as the non-living components (such as soil, water, air, and climate) that influence them. These living and non-living components interact with each other, creating a dynamic and interconnected system.

2. Biotic factors:
Living organisms within an ecosystem are referred to as biotic factors. They can include plants, animals, fungi, bacteria, and other microorganisms. These organisms interact with each other in various ways, such as through predation, competition, cooperation, and symbiosis. For example, plants convert sunlight into energy through photosynthesis, which is then consumed by herbivores. Herbivores are in turn consumed by carnivores, creating a food chain within the ecosystem.

3. Abiotic factors:
Abiotic factors are non-living components of an ecosystem that influence the organisms within it. These can include sunlight, temperature, water availability, soil composition, air quality, and climate patterns. Abiotic factors play a crucial role in shaping the structure and function of an ecosystem. For instance, temperature and precipitation patterns determine the types of plants and animals that can survive in a particular area.

4. Interactions within an ecosystem:
Within an ecosystem, there are numerous interactions taking place between biotic and abiotic factors. These interactions can be categorized into various ecological processes, such as energy flow, nutrient cycling, and population dynamics. Energy flows through an ecosystem in the form of food chains, with energy being transferred from one organism to another. Nutrient cycling refers to the movement and recycling of essential elements (like carbon, nitrogen, and phosphorus) through living organisms and the environment. Population dynamics involve changes in the size and distribution of populations within an ecosystem, influenced by factors like predation, competition, reproduction, and environmental conditions.

Conclusion:
In conclusion, an ecosystem is not just a group of green plants or a group of animals interacting with the environment. It is a functional unit that includes the entire community of organisms in a given area, interacting with both living and non-living components. The interactions between biotic and abiotic factors within an ecosystem are complex and essential for maintaining the balance and functioning of the ecosystem.