The Characteristics of Living Things Biology as the study of living things is a vast and fascinating field. To get a starting point in the study of biology, it is perhaps worthwhile to try to define what you mean by "life". Audesirk and Audesirk give a list of basic characteristics of living things. Karp approaches the same ideas in terms of the properties of living cells. Yockey has a very concise characterization of life: "The existence of a genome and the genetic code divides living organisms from nonliving matter." Classification of Organisms Energy cycle in living things

Index

Biology

Go Back

Classification of Organisms The word "organism" may be used to describe one individual living system. It can be thought of as the smallest unit of that kind of life that possesses all the characteristics of life. Audesirk & Audesirk supply the following table of characteristics used to classify organisms. Domain Kingdom Cell Type Cell Number Major Mode of Nutrition Bacteria ?? Prokaryotic Unicellular Absorption, photosynthesis Archaea ?? Prokaryotic Unicellular Absorption Eukarya Protista Eukaryotic Unicellular Absorption, ingestion, or photosynthesis Eukarya Fungi Eukaryotic Multicellular Absorption Eukarya Plantae Eukaryotic Multicellular Photosynthesis Eukarya Animalia Eukaryotic Multicellular Ingestion Those organisms that make use of photosynthesis manufacture their food by capturing energy from sunlight and constructing energy-rich molecules such as sugars and fats. These organisms are called "autotrophs", meaning "self-feeders". Other organisms must obtain their energy-rich molecules from other organisms and are called "heterotrophs" or "other-feeders".

Index

Biology

Go Back