Question

What set of characteristics do living organisms such as birds, trees, and bacteria have that distinguish them from nonliving things? Although viruses share many traits with other living organisms, some people do not consider them to be alive. For this question you may disregard viruses

Answer 1

Biologists have tried to distinguish the living things from non-living things and suggested eight characteristic features unique to living organisms.

The eight characteristics are: cellular, contain heredity material, perform metabolism, can reproduce and produce progenies, maintain homeostasis, sensible to the environment, show growth and development and can adapt to the environment.

Since, bacteria, birds and trees show this unique characteristic like they all are made up of cells, contain genetic material and others, therefore, are considered living organisms.

Viruses are considered non-living beings as they do not show the cellular characteristics like lack organelles, lack metabolism and cannot reproduce on their own.

Answer 2

The 7 (sometimes 8) characteristics of life are:
1. living things are composed of cells
2. living things have different levels of organization
3. living things metabolize (i.e. use energy)
4. living things respond to their environment
5. living things grow
6. living things reproduce
7. living things adapt to their environment
(some sources include) 8. living things have genetic material

Viruses do not metabolize, they do not grow, they do not adapt to their environment, and they cannot reproduce independently; viruses require host cells to reproduce and perform the other functions that give them the appearance of aliveness.