Biology is the study of life -- life in all of its grandeur. From the very small algae to the very large elephant, life has a certain wonder about it. With that in mind, how do we know if something is living? Is a virus alive or dead? What are the characteristics of life? These are all very important questions with equally important answers.
Characteristics of Life
Living tings include both the visible worlds of animals and plants as well as the invisible world of bacteria and viruses.On a basic level,we can say that life is ordered.Organismshave an enormously complex organization. We're all familiar with the intricate systems of the basic unit of life, the cell.
Life can also "work." No, not the daily employment variety, but living creatures can take in energy from the environment. This energy, in the form of food, is transformed to maintain metabolic processes and for survival.
Life grows and develops. This means more than just getting larger in size. Living organisms also have the ability to rebuild and repair themselves when injured.
Life can reproduce. Have you ever seen dirt reproduce? I don't think so. Life can only come from other living creatures.
Life can respond. Think about the last time you accidentally stubbed your toe. Almost instantly, you flinched back in pain. Life is characterized by this response to stimuli.
Finally, life can adapt and respond to the demands placed on it by the environment. There are three basic types of adaptations that can occur in higher organisms.
*Reversible changes occur as a response to changes in the environment. Let's say you live near sea level and you travel to a mountainous area. You may begin to experience difficulty breathing and an increase in heart rate as a result of the change in altitude. These symptoms go away when you go back down to sea level.
*Somatic changes occur as a result of prolonged changes in the environment. Using the previous example, if you