The ecosystem includes a total of the abiotic and biotic components of a region. These components interact with each other and make the ecosystem self-sufficient in terms of energy and nutrients. Climatic conditions, physical factors, soil type, and its feature together make the non-living or abiotic part of an ecosystem. They interact among themselves and with the living components by nutrient cycling. All the species of living beings together make the biotic components of an ecosystem. They interact with each other by food chains and food webs.
Oceans are an example of the aquatic ecosystem while deserts are terrestrial ecosystems.
All the cells in a person's body have the same DNA and the same genes. However, the difference between cells in different tissues and organs is that the "expression" of the genes differs between cells. Expression means that the message from the DNA is being copied and made into protein.
