These notes explain some basic laws and definitions of energy in general and how organisms use energy.

Essay by TrueHigh School, 10th gradeA+, January 2004

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Energy - the ability to do work (move matter)

2 types: Kinetic Energy - energy doing work

ex: heat (moving molecules)


Potential Energy­­ - stored energy; can be as a result of

location or arrangement

ex: roller coaster - at 100 ft high there is more

potential energy than at 25 ft high

cells - molecules have potential energy due to the arrangement of the atoms

Chemical Energy - potential energy of molecules important for living organisms


Thermodynamics - study of energy transformations in matter

1st Law of Thermodynamics: Energy cannot be created or

destroyed only transferred or transformed

ex: electric company doesn't create energy, it converts it to a useable form; car converts gasoline (potential energy) into kinetic energy; we convert food into kinetic energy

2nd Law of Thermodynamics: Energy conversions reduce order in the universe (when energy is converted into another form, there is an increase in disorder or randomness)

Entropy - the amount of disorder in a system

Heat is a form of disorder (random molecular motion)

ex 1: fuel in tank of car - all of the chemical energy that is

converted into kinetic energy will eventually be

converted into heat energy.

When stopping car, the

friction between the tires and the road and the brakes

and the tires creates heat.

ex 2: Cells - creates ordered structures from less organized ones (ex: formation of proteins) but surroundings

become less organized because some energy escapes as heat

**Work of cells is powered by the potential energy contained in molecules

Problem: Describe the energy transformations that occur when you climb to the top of a stairway.

Chemical Reactions Either Store or Release Energy

Endergonic Reactions - (energy in)

- Requires an INPUT of energy for the reaction to happen

- Produce products that...