Chapter 8.1.2 (Exam 2) Energy

Question 1

What is entropy (S)?

Answer 1

a measure of the disorder in a system

Question 2

Why does disorder tend to increase? How does this relate to an organism’s intake of energy?

Answer 2

Disorder tends to increase because of energy transformations

Living organisms must have a constant supply of energy to maintain order

Question 3

What is enthalpy (H) in biological systems?

Answer 3

Total energy

Question 4

What is free energy (G) in biological systems?

Answer 4

Usable energy that can do work

Question 5

How is entropy expressed in biological systems?

Answer 5

Unusable energy is represented by entropy (S) multiplied by the absolute temperature (T)

Question 6

Change in energy can be measured in calories or joules. What is the formula for change in free energy (ΔG) of a chemical reaction?

Answer 6

ΔG = ΔH - TΔS

ΔG = G_products - G_reactants

Question 7

Explain the spontaneity of a chemical reaction.

Answer 7

If ΔG is +, free energy is required, nonspontaneous reaction

If ΔG is –, free energy is released, spontaneous reaction

Question 8

Describe endergonic reactions.

Answer 8

Endergonic reactions require free energy

Anabolism makes a single product (a highly ordered substance) out of many smaller reactants (less ordered)—complexity (order) increases

Question 9

Describe exergonic reactions.

Answer 9

Exergonic reactions release free energy

Catabolism breaks down an ordered reactant into smaller, more randomly distributed products—complexity decreases (generates disorder)

Question 10

Chemical reactions are reversible. What does the direction of the reaction depend on?

Answer 10

The concentration of the reactants and the products

Question 11

What is chemical equilibrium?

Answer 11

Chemical equilibrium: balance between forward and reverse reactions, a state of no net change, ΔG = 0