THE STUDY OF LIFE

What is Biology? Biology is the study of life.  “bio” = life  “logy” = study

How do we know if something is living?

The 8 Characteristics of Life 1.are MADE UP OF CELLS 2.REPRODUCE 3.must OBTAIN AND USE ENERGY (Metabolism) 4.maintain STABLE INTERNAL ENVIRONMENT (Homeostasis) 5.have a UNIVERSAL GENETIC CODE (Heredity) 6.RESPOND TO ENVIRONMENT (Adaptation) 7.GROW AND DEVELOP 8.CHANGE OVER TIME (Evolve) Living things…

1. Made up of Cells All living things are made of one or more cells. (unicellular or multicellular) –Uni = one –Multi = many A cell is the smallest unit capable of all life functions. Cells are highly organized.

2. Reproduction All living things produce offspring. Since nothing can live forever, reproduction is essential to life.

3. Obtain and Use Energy (Food/Nutrients) All living things use energy to grow, to move, and to process information. Metabolism is the sum off all the chemical reactions in the above activities.

4. STABLE INTERNAL ENVIRONMENT All living things must maintain a stable internal environment in order to function properly. Homeostasis is the term given to keeping a balanced internal environment.

5. UNIVERSAL GENETIC CODE Heredity is the passing of traits from parent to offspring. All living things are able to pass on their characteristics (traits) to their offspring.

6. Respond to Environment Response is a reaction to stimulus Adaptation Example: Sneezing due to dust, plants growing toward any type of light, birds migrating due to changes in the seasons.

7. Growth and Development All living things undergo a growth and development process. It may be a simple increase in size or a complex change of structures and their functions. (Metamorphosis)

8. Change over Time Evolution Taken as a group, all living things change over time.

Some Misconceptions 1. Movement (plants are alive but do not move about) 2. Complexity (a computer is not alive but it is complex) 3. Death (a car breaks down but cannot die) Sometimes we mistakenly think that living things can be defined by the following traits as well:

Levels of Organization Atom – smallest unit of chemical compounds

Levels of Organization Molecules – groups of atoms

Levels of Organization Cells – smallest functional unit of life

Levels of Organization Groups Of Cells → Tissue

Levels of Organization Groups of tissue → organ

Levels of Organization Groups of Organs → organ system

Levels of Organization Organ systems → Organisms

LEVELS OF ORGANIZATION Organism Organ Systems Organs Tissues Cells Molecules Atoms