Theme #1 - Cells

All living things are composed of one ormore cells.

Different types of cells have different"jobs" within the organism. Each life form begins from one cell,which then will split. These cells split, and so on. After this has happenedseveral times, differentiation is undergone, when the cells change so that theyare not the same thing anymore. Then they are used to begin to put together thefinal organism, some cells, for example, as the eyes, some as the heart, etc.The only arguable exception to this is viruses. They are not composed of cells,but are said to be "living."

Theme#2 - Organization

Complex organization patterns are found inall living organisms. They arrange themselves on very small levels, groupinglike things together. On larger levels, they become visible. This also has todo with differentiation, as the cells are organized in a manner that makessense for the organism after they change to what they be in the final organism.

Theme#3 - Energy Use

All organisms use energy. The sum of thechemical energy they use is called metabolism. This energy is used to carry outeverything they do. Autotrophs (plants) use energy from the sun forphotosynthesis, to make their own food (glucose). Heterotrophs (animals andhumans) must ingest food for this purpose.

Theme#4 - Homeostasis

All organisms have stable internalconditions which must be maintained in order to remain alive. These includetemperature, water content, heartbeat, and other such things. In a way, thishas to do with energy use, because a certain level of energy must be keptwithin the body at all times. For this, obviously, humans must then ingest foodon a regular basis. Not all conditions are for the body to maintain itself;though most are.

Theme#5 - Growth

All organisms grow and change. Cells divideto form new, identical cells. Differentiation happens, as well, when cellsmutate into other types of cells, making a more complex organism. Organismsgrowing, changing, and becoming more complex is called development. Single-celled organisms do grow as well, but they will only become slightly larger �thisis nearly unmeasurable.

Theme#6 - Reproduction

All organisms reproduce in order tocontinue the species‘ life. This is combining genetic information (in sexualreproduction) or splitting into two organisms (in asexual reproduction) inorder to create another of the same species. In sexual reproduction, the neworganism will have some characteristics from the mother, and some from father.It may look like either of them, or it may not. In asexual reproduction, thenew organism is an exact copy of the first. Sometimes, not every member of aspecies is able to reproduce. As long as others are (which we know they can, ifthey still exist today) then it does not threaten the species.