Characteristics of Living Organisms — Core Principles
Core Principles
Living organisms are distinguished from non-living matter by a unique set of characteristics. These include growth, reproduction, metabolism, cellular organization, and consciousness. Growth is an increase in mass and number, but it's not defining because non-living things can also grow extrinsically.
Reproduction, the ability to produce offspring, is also not defining as sterile organisms exist. Metabolism, the sum of all chemical reactions within an organism, is a defining feature because it's exclusive to life and universal among living beings.
Cellular organization, meaning all life is composed of cells, is another defining characteristic as cells are the fundamental units of life. Lastly, consciousness, the ability to sense and respond to the environment, is defining because it's unique to living systems.
Other emergent properties like homeostasis, adaptation, and evolution further characterize life.
Important Differences
vs Defining vs. Non-Defining Characteristics of Life
| Aspect | This Topic | Defining vs. Non-Defining Characteristics of Life |
|---|---|---|
| Universality (present in all living organisms) | Yes (Metabolism, Cellular Organization, Consciousness) | No (Growth, Reproduction - due to exceptions) |
| Exclusivity (found only in living organisms) | Yes (Metabolism, Cellular Organization, Consciousness) | No (Growth - non-living objects grow by accretion; Reproduction - no non-living equivalent, but not universal among living) |
| Examples | Metabolism (anabolism, catabolism), Cellular organization (cells as basic units), Consciousness (response to stimuli) | Growth (mountains grow), Reproduction (mules are sterile) |
| Significance for defining life | Essential and sufficient criteria to distinguish living from non-living. | Important features of life, but not sufficient on their own to define life. |