Some of these changes make no difference to the organism, whereas others can change cells and organisms. Only mutations in germ cells can create the variation that changes an organism's offspring. Science NSES Content Topic Biological Evolution Species evolve over time. Biological classifications indicate how organisms are related. Organisms are classified into a hierarchy of groups and subgroups based on their evolutionary relationships.
Species is the most fundamental unit of classification.
The energy for life ultimately derives from the sun. In addition, the bonds between the atoms can be used as sources of energy for life processes. Each transformation results in the storage and dissipation of energy into the environment as heat. Matter and energy are conserved in each transformation. The Nervous System and the Behavior of Organisms Like other aspects of an organism's biology, behaviors have evolved through natural selection.