What are the processes that distinguish life from non-life?

Question

Also, tell me please how you can tell something that is living from something that isn't.

Answer 1

Living organisms have a bunch of biological processes that non-living organisms don't have:

Respiration
Reproduction
Eating/Consumption
Elimination
Maintaining a stable internal environment (Homeostasis)
Growth - manufacture of new parts/proteins/etc (Autopoiesis)
Adaptation/Response to external stimuli
Complexity
Behaviour

Answer 2

Do your homework. Read your book. You are only short changing yourself in the long run if you think people on the internet will do everything for you.

If you don't understand, its usually because your textbook is a children's book and your course material is college level. Go to your nearest college bookstore or order a decent textbook online. Read it and do some of the problems.

Answer 3

From Wikipedia:

There is no universal definition of life; there are a variety of definitions proposed by different scientists.To define life in unequivocal terms is still a challenge for scientists.

Conventional definition: Often scientists say that life is a characteristic of organisms that exhibit the following phenomena:

1. Homeostasis: Regulation of the internal environment to maintain a constant state; for example, sweating to reduce temperature.
2. Organization: Being composed of one or more cells, which are the basic units of life.
3. Metabolism: Consumption of energy by converting nonliving material into cellular components (anabolism) and decomposing organic matter (catabolism). Living things require energy to maintain internal organization (homeostasis) and to produce the other phenomena associated with life.
4. Growth: Maintenance of a higher rate of synthesis than catalysis. A growing organism increases in size in all of its parts, rather than simply accumulating matter. The particular species begins to multiply and expand as the evolution continues to flourish.
5. Adaptation: The ability to change over a period of time in response to the environment. This ability is fundamental to the process of evolution and is determined by the organism's heredity as well as the composition of metabolized substances, and external factors present.
6. Response to stimuli: A response can take many forms, from the contraction of a unicellular organism when touched to complex reactions involving all the senses of higher animals. A response is often expressed by motion, for example, the leaves of a plant turning toward the sun or an animal chasing its prey.
7. Reproduction: The ability to produce new organisms. Reproduction can be the division of one cell to form two new cells. Usually the term is applied to the production of a new individual (either asexually, from a single parent organism, or sexually, from at least two differing parent organisms), although strictly speaking it also describes the production of new cells in the process of growth.

However, others cite several limitations of this definition. Thus, many members of several species do not reproduce, possibly because they belong to specialized sterile castes (such as ant workers), these are still considered forms of life. One could say that the property of life is inherited; hence, sterile or hybrid organisms such as the mule, liger or eunuchs are alive although they are not capable of self reproduction. However, non-reproducing organisms may still propagate through mechanisms such as kin selection.

Viruses and aberrant prion proteins are often considered replicators rather than forms of life, a distinction warranted because they cannot reproduce without very specialized substrates such as host cells or proteins, respectively. However, most forms of life rely on foods produced by other species, or at least the specific chemistry of Earth's environment.

Still others contest such definitions of life on philosophical grounds. They offer the following as examples of life: viruses which reproduce; storms or flames which "burn"; certain computer software programs which are programmed to mutate and evolve; future software programs which may evince (even high-order) behavior; machines which can move; and some forms of proto-life consisting of metabolizing cells without the ability to reproduce. Still, most scientists would not call such phenomena expressive of life. Generally all seven characteristics are required for a population to be considered a life form.


The systemic definition of life is that living things are self-organizing and autopoietic (self-producing). These objects are not to be confused with dissipative structures (e.g. fire).

Variations of this definition include Stuart Kauffman's definition of life as an autonomous agent or a multi-agent system capable of reproducing itself or themselves, and of completing at least one thermodynamic work cycle.

Yet other definitions of life are:

1. Living things are systems that tend to respond to changes in their environment, and inside themselves, in such a way as to promote their own continuation.[citation needed]
2. Life is a charateristic of self-organizing, cannibalistic systems consisting of a population of replicators that are capable of mutation, around most of which homeostatic, metabolizing organisms evolve. This definition does not include flames, but does include worker ants, viruses and mules. Self reproduction and energy consumption is only one means for a system to promote its own continuation. This explains why bees can be alive and yet commit suicide in defending their hive. In this case the whole colony works as such a living system.
3. Type of organization of matter producing various interacting forms of variable complexity, whose main property is to replicate almost perfectly by using matter and energy available in their environment to which they may adapt. In this definition "almost perfectly" relates to mutations happening during replication of organisms that may have adaptative benefits.

Contradictions in definitions

Most of the definitions are focused on differentiating between living material and non-living material. Some new ideas were proposed in the years between 1980 and 1990. It is still not clear whether computer software exists that could be considered as alive. Some computer software shows certain resemblances with living organisms. It is not difficult, in an algorithmic sense, to create software which fulfills some base criteria (growth, reproduction, reaction to environmental changes, etc.).

Consider an artificial environment with certain properties (for example, a system which is calling the processes with different input). If a process is able to solve the problem (respond with a correct output) within a given time limit, it can survive; otherwise, the process is deleted. If the process solves the problem before the other processes, it gets higher part from the computer resources. This is a very simple model of an environment in which life has been simulated. More sophisticated environments can also be created. Although in most of the simulations the systems collapse relatively quickly (for example, none of the processes are able to adapt and solve the given problem), it has not yet been formally proved that such an environment can not exist permanently. Such an environment would meet all the criteria of simple life definitions.

If ever such a theorem could be formally proved, it will be necessary to reconsider the definitions or admit that the computer world is a good approximation of the real one.