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Biology : The Study Of Life Notes 1-1. Biologists have devised a list of 7 characteristics that define life. Something can be considered alive ONLY if it displays ALL 7 of the characteristics. Anything that possesses all 7 of the characteristics of life is called an organism.
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Biologists have devised a list of 7 characteristics that define life. • Something can be considered alive ONLY if it displays ALL 7 of the characteristics. • Anything that possesses all 7 of the characteristics of life is called an organism. The Characteristics of Life
1. Display cellular organization: • Cell = the basic unit of structure and function in all living things. • Smallest unit that can perform all life’s • processes. • Living things are made of one cell (unicellular) or many cells (multicellular). The Characteristics of Life
The Characteristics of Life • For complex multicelluar organisms, cells specialize. • Levels of Organization: -Cells form tissues -Tissues form organs -Organs form organ systems
The Characteristics of Life 2. Respond to Stimuli They are able to react, or respond to an environmental condition, or stimulus. Venusflytrap
3. Maintains Homeostasis: The Characteristics of Life • All organisms are able to maintain a relatively constant internal environment. • Homeostasis: The regulation of an organism’s internal environment to maintain conditions suitable for life. • Example – maintaining a constant body temperature – sweating
The Characteristics of Life 4. Metabolism • Organisms require energy to perform life processes such as repair, movement, or growth. • Metabolism = the sum of all the chemical reactions that take in an transform energy and materials from the environment. • Some organisms use light energy from the sun to make their own food and fuel their activities; while, other organisms that cannot make their own food get energy by consuming other organisms.
5. Grow and Develop: • All living organisms grow and develop during their life spans. • Growth: an increase in the size of an organism due to an increase in the size and number of cells • Development: all of the changes that take place throughout the life span of an organism The Characteristics of Life
6. Reproduction: • All organisms produce offspring like themselves. • Although reproduction is not essential to the survival or an individual organism, it is essential for the continuation of a species. The Characteristics of Life
All living organisms contain genetic information that can be passed on through generations. • Heredity information is transmitted through a molecule called DNA. • Gene = segment of DNA that contains instructions for a specific trait. The Characteristics of Life
The Characteristics of Life 7. Evolve Over Time • Although individual organisms change during their lifetime, their genetic characteristics do not. • However, populations of living things do change over time (evolve). • Ability to evolve is essential for survival in a changing world.