Chapter 3: Energetics

Front

What does the second law of thermodynamics state about entropy?

Back

The second law of thermodynamics states that the entropy (disorder) of the universe tends to increase over time.

Front

How do cells comply with the second law of thermodynamics while building ordered structures?

Back

Cells release heat, carbon dioxide, water, and other waste products into their surroundings during metabolism, increasing the entropy of the environment, thus complying with the second law.

Front

What are oxidation and reduction reactions?

Back

Oxidation involves the loss of electrons or hydrogen atoms, often with the addition of oxygen. Reduction involves the gain of electrons or hydrogen atoms, typically with the removal of oxygen.

Front

How do enzymes affect activation energy?

Back

Enzymes lower the activation energy (Ea) needed to reach the transition state, thus accelerating chemical reactions.

Front

What is Gibbs free energy (G)?

Back

Gibbs free energy (G) is the energy available to do work in a system. ΔG indicates the change in free energy during a reaction.

Front

What does a negative ΔG indicate?

Back

A negative ΔG indicates that a reaction is spontaneous (exergonic).

Front

What is entropy (S)?

Back

Entropy is a measure of the disorder or randomness of a system. Systems tend to move toward greater entropy.

Front

What is enthalpy (H)?

Back

Enthalpy (H) refers to the total heat content of a system, mostly reflecting bond energies.

Front

How does temperature affect reaction spontaneity according to the equation ΔG = ΔH – TΔS?

Back

At high temperatures, the entropy term (TΔS) becomes more significant, making reactions with positive ΔS more likely to be spontaneous.

Front

What happens during carbon oxidation?

Back

Carbon atoms lose hydrogen atoms or gain oxygen atoms, releasing energy. Reduced carbon contains more stored energy, while oxidized carbon has less energy.