The sustainable functional unit of biosphere is called an ecosystem. An ecosystem is a community of living organisms that interact with each other and with their non-living environment. It consists of biotic components such as plants, animals, and microorganisms, as well as abiotic components like air, water, soil, and sunlight.

Components of an Ecosystem:
1. Biotic Components: They are the living components of the ecosystem. They include plants, animals, and microorganisms. They interact with each other, forming complex food webs and nutrient cycles.

2. Abiotic Components: They are the non-living components of the ecosystem. They include air, water, soil, sunlight, and minerals. They provide the necessary resources and conditions for the survival of the biotic components.

Types of Ecosystems:
1. Terrestrial Ecosystems: They are the ecosystems that exist on land. They include forests, grasslands, deserts, and tundra.

2. Aquatic Ecosystems: They are the ecosystems that exist in water. They include oceans, lakes, rivers, and wetlands.

Functions of Ecosystems:
1. Nutrient Cycling: Ecosystems recycle nutrients such as carbon, nitrogen, and phosphorus, which are essential for the growth and survival of living organisms.

2. Energy Transfer: Ecosystems transfer energy from the sun to living organisms through the process of photosynthesis, and from one organism to another through food chains and food webs.

3. Climate Regulation: Ecosystems play a vital role in regulating the Earth's climate by absorbing carbon dioxide from the atmosphere and producing oxygen.

4. Water Cycle: Ecosystems regulate the water cycle by absorbing and releasing water through the processes of evaporation, transpiration, and precipitation.

In conclusion, an ecosystem is a sustainable functional unit of the biosphere that consists of living and non-living components that interact with each other. Ecosystems play a crucial role in maintaining the balance of the biosphere and are essential for the survival of all living organisms.

Ecosystem