this is the part you should be concerned with:

The Meaning of LIFE -

Starting from a Biological Viewpoint

The 1997 Random House College Dictionary defines life as:

"The general condition that distinguishes organisms from inorganic objects and dead organisms,

being manifested by

growth through metabolism,

a means of reproduction,

and internal regulation in response to the environment."


Similarly, the 1982 American Heritage Dictionary defines life as:

"The property or quality maintained in functions such as

metabolism,

growth,

response to stimulation, and

reproduction,

by which living organisms are distinguished from dead organisms or from inanimate matter".


So, both of these definitions are similar - life is a property, quality, or condition that includes metabolism, growth, response to the environment or to stimulation, and reproduction. Let's clarify these a bit :

Metabolism: "...chemical and physical processes...by which its substance is produced, maintained and destroyed, and by which energy is made available" (Random House College Dictionary again)
Growth: a gradual increase in size, perhaps to a maximum
Response to the environment or stimulation: as things around the living thing change, the living thing tried to adapt to stay alive; if it cannot adapt enough to the change, the living thing may die
Reproduction: the form of life can give rise to another, similar form of life.
Now, most of the things we think of as alive meet those four requirements. We human beings have chemical and physical processes, like breathing and moving our arms and legs. While plants don't breathe, nor move arms and legs, they have chemical processes that use light to make food (photosynthesis) and have physical processes to move water inside, for example.

We human beings grow, until we stop growing. So do plants, and so do single cell organisms such as bacteria.

We human beings respond to the environment. Plants do, too, though often at a slower rate than animals, and often in very different ways - like gradually growing towards light. And, in the extreme case, human beings die, and plants die.

We also reproduce, as do plants, and bacteria. Some living things are incapable of reproduction. For example, mules are sterile - a mule is the offspring of a horse and a donkey, but cannot reproduce itself.