LIVE

Life is a characteristic that distinguishes objects that have signaling and self-sustaining processes from those that do not either because such functions have ceased (death), or else because they lack such functions and are classified as inanimate. Biology is the science concerned with the study of life.

Any contiguous living system is called an organism. Organisms undergo metabolism, maintain homeostasis, possess a capacity to grow, respond to stimuli, reproduce and, through natural selection, adapt to their environment in successive generations. More complex living organisms can communicate through various means. A diverse array of living organisms can be found in thebiosphere of Earth, and the properties common to these organisms—plants, animals, fungi, protists, archaea, and bacteria—are acarbon- and water-based cellular form with complex organization and heritable genetic information.

Scientific evidence suggests that life began on Earth

 approximately 3.5 billion years ago. The mechanism

 by which life emerged on Earth is unknown although 

many hypotheses have been formulated. Since then,

   Plants in the Rwenzori Mountains, Uganda    

life has evolved into a wide variety of forms, which

biologists have classified into a hierarchy of taxa.

Life can survive and thrive in a wide range of conditions. 

The meaning of life—its significance, origin, purpose, and ultimate   fate is a central concept and question in philosophy and religion.     

Plant growth in the Hoh Rainforest

Both philosophy and religion have offered interpretations as to 

how life relates to existence and consciousness, and on related                             

issues such as life stance, purpose, conception of a god or gods,

a soul or an afterlife. Different cultures throughout history have had

widely varying approaches to these issues..

                                                                                                        

Biology

Since there is no unequivocal definition of life, the current understanding is descriptive. Life is considered a characteristic of organisms that exhibit all or most of the following characteristics or traits:^[29][31][32]

1. Homeostasis: Regulation of the internal environment to maintain a constant state; for example, electrolyte concentration or sweating to reduce temperature.
2. Organization: Being structurally composed of one or more cells — the basic units of life.
3. Metabolism: Transformation of energy by converting chemicals and energy 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 anabolism than catabolism. A growing organism increases in size in all of its parts, rather than simply accumulating matter.
5. Adaptation: The ability to change over time in response to the environment. This ability is fundamental to the process of evolution and is determined by the organism'sheredity, diet, and external factors.
6. Response to stimuli: A response can take many forms, from the contraction of a unicellular organism to external chemicals, to complex reactions involving all the senses of multicellular organisms. A response is often expressed by motion; for example, the leaves of a plant turning toward the sun (phototropism), and chemotaxis.
7. Reproduction: The ability to produce new individual organisms, either asexually from a single parent organism, or sexually from two parent organisms.

These complex processes, called physiological functions, have underlying physical and chemical bases, as well as signaling and control mechanisms that are essential to maintaining life. 

An aerial photo of microbial mats around
theGrand Prismatic Spring of Yellowstone National Park

Herds of zebra and impala gathering on theMaasai Mara plain