3.1

Question 1

Energy

Answer 1

• All living things require energy
• Used for growth, repair, and Maintenance
• Brain makes up only 2% of body mass, but uses up 20% of energy

Question 2

ATP & Metabolism

Answer 2

• ATP is used in mitochondria
• Metabolism: the sum of chemical reactions taken place within an organism
• Anabolic to build
• Catabolic to breakdown

Question 3

Most organisms obtain energy using….

Answer 3

1. Directly from sun via photosynth.
2. Consuming energy from food

Question 4

Kinetic and Potential Energy

Answer 4

1. Kinetic Energy
   - Occurs as a result of motion
   - Preform work by making other objects move
2. Potential Energy
   - Energy stored within an object

Chemical potential energy:
- energy stored within good molecules

Gravitational potential energy
- energy stored within high elevation

Question 5

The First Law of Thermodynamics

Answer 5

• Energy cannot be created nor destroyed, it can only change forms

Question 6

Energy and Chemical bonds

Answer 6

• Converting energy from one form to another, must reiqure chem. bonds to be broken, and other bonds to be formed
• Bonds broken in reactants (energy is absorbed)
• Bonds formed in products (energy is released)

Question 7

Bond Energy

Answer 7

• Measure of stability of a chemical bond
• All chemical reactions require energy to start

Activation Energy:
- Minimum amount of energy required to break a bond/start rxn

Transition State:
- temporary state where bonds have reached their breaking point, and new bonds are ready to be formed

Question 8

Exo/Endo

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Answer 8

• Ea=E(transition state) -E(reactants)
• Transfer of heat

Exothermic Rxn = net absorbtion

Endothermic Rxn = net release of energy

Question 9

The Second Law of Thermodynamics

Answer 9

Everytime energy is converted into another form, some of the energy becomes unuseful (usually thermo Eng)

• This increases the entropy of the universe
• Cell converts only 40% of energy int glucose, other 60% is released as heat

Question 10

Entropy and Ex

Answer 10

• Degree of disorder in a system
• Total entropy is a system is always increasing

Entropy increases when:

• Solid reacts to form liquids/gas
• Liquids form gas products
• Total product molecules > total reactants

Question 11

Entropy in Living organinisms

Answer 11

• Our body systems attempts to decrease entropy. While entropy of organism decreases, entropy of universe increases

Question 12

Spontaneous Changes

and non-spontanous

Answer 12

• Change occurs once it has started, does not require continual source of energy

Endothermic: sweat

Exothermic: wood burning

Non-spontanous: need continueal supply of energy

Question 13

Gibbs Free Energy

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Answer 13

Free energy: energy that works, useful

• Transfer of energy

is Gibss = (-) exogonic —> spontaneous, oxidation of glucose

G = (+) endergonic —> non-spontanous, photosynth.

Question 14

Coupled Reactions

Answer 14

Energy coupling: energy released from endogenic is used for exergonic
- combined have a g=(-) –> spontaneous

• Endergonic rxns must be coupled with exergonic rxns that
  release more free energy than the endergonic rxn requires
• products of one
  reaction are used immediately as reactants for the next reaction
  in the pathway

Question 15

Catabolic Pathway & Anabolic Pathway

Answer 15

Catabolic Pathway
* complex molecules broken down, releasing energy
* (e.g. cellular respiration) ΔG -ve

Anabolic Pathway
* simple molecules combined, consuming energy
* (e.g. photosynthesis) ΔG +ve