There are three types of systems in thermodynamics: open, closed, and isolated. An open system can exchange both energy and matter with its surroundings. The stovetop example would be an open system, because heat and water vapor can be lost to the air. A closed system, on the other hand, can exchange only energy with its surroundings, not matter.
It also allowed gills to specialize in gas exchange (rather than serve the dual function of gas exchange and filter feeding). 2. No series of fossils shows the stages of jaw development, but embryological evidence suggests that they evolved by modifying slender bones in the throat region that support the gill arches of jawless fish. a.