Essay by ilnet2000High School, 12th grade November 2005

download word file, 2 pages 4.0

6.1 Energy

A. Energy

1. Energy is capacity to do work; cells must continually use energy to do biological work.

2. Kinetic energy is energy of motion; all moving objects have kinetic energy.

3. Potential energy is stored energy.

a. Water behind a dam has potential energy that can be converted to kinetic energy.

b. Energy within an atom lies in arrangement of its atoms in molecule; glucose has more

energy than its breakdown components, carbon dioxide and water.

B. Two Laws of Thermodynamics

1. First law of thermodynamics (also called the law of conservation of energy)

a. Energy cannot be created or destroyed; it can be changed from one form to another.

b. In an engine, chemical energy of coal converts to heat; heat energy converts to kinetic energy.

c. In human body, chemical energy in food is converted to chemical energy in ATP and then

converted to mechanical energy of muscle contraction.

2. Second law of thermodynamics

a. Energy cannot be changed from one form into another without a loss of usable energy.

b. 25% of chemical energy of gasoline is converted to move a car; rest is lost as heat.

c. When muscles convert chemical energy in ATP to mechanical energy, some is lost as heat.

d. Heat is form of energy but quickly dissipates into the environment; because heat dissipates,

it can never be converted back to the form of potential energy.

C. Entropy

1. Entropy is measure of randomness or disorder.

2. Organized usable forms of energy have low entropy; unorganized/less stable forms have high entropy.

3. Energy conversions result in heat and therefore the entropy of the universe is always increasing.

4. It takes a constant input of usable energy from the food you eat to keep you organized.

6.2 Metabolic Reactions and...