Activity 3: What Do You Think?
Metabolic processes involve chemical reactions that release energy (exergonic reactions), and reactions that require energy to occur (endergonic reactions). Exergonic reactions provide for the energy needs of endergonic reactions.
However, not all of the energy released by an exergonic reaction is free to be
used by an endergonic one. There is always some “waste” energy in the form
of heat. This is the source of the heat.
Student Conceptions
Students often think of energy as a thing. We are probably all responsible for this misconception, since we frequently will say, “close the door so you don’t let the heat out (or the cold in).” With that comment we imply that heat is a thing, just as a cat and dog can be prevented from leaving by closing a door. This misconception may be further strengthened by talking about a flow of energy, leaving students to believe that energy is a type of fluid that is transferred in certain processes.
Some students may think of energy only in terms of activity. The fact that energy
is defined as the ability to do work may contribute to this misconception. Students should be aware of the fact that although one form of energy, kinetic energy, is associated with movement, stored energy, or potential energy, is not associated with any type of activity. |