BIOLOGY : 
Biology is defined as the study of living organisms, their origins, anatomy, morphology, physiology, behaviour, and distribution."
What is an Ecosystem?
The ecosystem is the structural and functional unit of ecology where the living organisms interact with each other and the surrounding environment. In other words, an ecosystem is a chain of interaction between organisms and their environment. 
Types of Ecosystem:
There are two types of ecosystem:
Terrestrial Ecosystem
Aquatic Ecosystem
Terrestrial Ecosystem:
Terrestrial ecosystems are exclusively land-based ecosystems. There are different types of terrestrial ecosystems distributed around various geological zones. They are as follows:
Forest Ecosystems
Grassland Ecosystems
Tundra Ecosystems
Desert Ecosystem
Forest Ecosystem:
A forest ecosystem consists of several plants, animals and microorganisms that live in coordination with the abiotic factors of the environment. Forests help in maintaining the temperature of the earth and are the major carbon sink.
Grassland Ecosystem:
In a grassland ecosystem, the vegetation is dominated by grasses and herbs. Temperate grasslands, savanna grasslands are some of the examples of grassland ecosystems.
Tundra Ecosystem:
Tundra ecosystems are devoid of trees and are found in cold climates or where rainfall is scarce. These are covered with snow for most of the year. The ecosystem in the Arctic or mountain tops is tundra type.
Desert Ecosystem:
Deserts are found throughout the world. These are regions with very little rainfall. The days are hot, and the nights are cold.
Aquatic Ecosystem:
Aquatic ecosystems are ecosystems present in a body of water. These can be further divided into two types, namely:
Freshwater Ecosystem
Marine Ecosystem
Freshwater Ecosystem:
The freshwater ecosystem is an aquatic ecosystem that includes lakes, ponds, rivers, streams and wetlands. These have no salt content in contrast with the marine ecosystem.
Marine Ecosystem:
The marine ecosystem includes seas and oceans. These have a more substantial salt content and greater biodiversity in comparison to the freshwater ecosystem.
Functions of the Ecosystem:
The functions of the ecosystem are as follows:
It regulates the essential ecological processes, supports life systems and renders stability.
It is also responsible for the cycling of nutrients between biotic and abiotic components.
It maintains a balance among the various trophic levels in the ecosystem.
It cycles the minerals through the biosphere.
The abiotic components help in the synthesis of organic components that involves the exchange of energy.