Why is a living thing a system?

Actually a living thing is not a system. Every part of our body, like our lungs brain or heart, can be seen as a separate system. Therefore we are giant arrays of systems working together to keep you alive

Well, the "system" is basically a group of factors that are related in some way. So, ideally you'd be able to think of a individual organism as a living system.

Wetlands form where water and land meet. a lake with a wetland fringe can fill in with decayed plant and animal material to become a wet meadow. a pond can fill in to become a bog or fen. sediment can fill in a river marsh to become a swamp.flooding of coastal lowlands from rising sea levels has created broad coastal marshes that are protected from wave action by barrier islands or reefs. coastal wetlands also form when rivers deposit sediment as they reach the ocean. plants then take root and hold the soil firm against the forces of tides and waves.

More; less is the correct answer