Topic 2: Thermodynamics

Question 1

Example of an isolated system

Answer 1

The universe

Question 2

Closed system?

Answer 2

Allows energy but not matter to pass through

Question 3

Open system?

Answer 3

Allows energy and matter to pass through

Question 4

Relative Ep of molecules with non-polar covalent bonds

Answer 4

Higher Ep in general

Question 5

Examples of non-polar covalent bonds?

Answer 5

C-C, C-H, C8H18 (gasoline)

Question 6

An important source of cellular energy

Answer 6

Electrochemical Gradient

Question 7

First law of thermodynamics?

Answer 7

energy cannot be created or destroyed

Question 8

Enthalpy (3 points)

Answer 8

The sum of all potential and kinetic energy present in a system
Can be positive or negative, depending on reaction
Changes when work occurs

Question 9

Entropy (3 points)

Answer 9

How dispelled energy is in the universe
Can be positive or negative, depending on reaction
Must always increase

Question 10

When ΔS>0…

Answer 10

energy has become more dispered

Question 11

When ΔS<0…

Answer 11

Energy has become less dispered

Question 12

Second law of thermodynamics

Answer 12

the total entropy of the universe must always increase

Question 13

What determines the spontaneity of a reaction?

Answer 13

Entropy! ΔS must be larger than 0

Question 14

Two types of entropy?
Why are they important?

Answer 14

Entropy of system, and entropy of surroundings
Even if the entropy of the system decreases, as long as the entropy of the surroundings increases to a greater degree, reaction is spontaneous. ΔS>0

Question 15

Describe Free Energy (G)

Answer 15

Molecules have free energy, meaning the ‘extra’ energy in a system that is free to do work

Question 16

When ΔG>0….

Answer 16

energy is not available for work to occur

Question 17

When ΔG<0…

Answer 17

energy is available for work to occur

Question 18

Exergonic means…

Answer 18

a reaction will happen (spontaneous)

Question 19

For the reaction to be exergonic and spontaneous…

Answer 19

ΔS>0 and ΔG<0

Question 20

What units does ΔG use?

Answer 20

kJ/mol

Question 21

What units does ΔS use?

Answer 21

J/mol

Question 22

When will ΔG=0?

Answer 22

When chemical equilibrium is reached

Question 23

The sum of all reactions in a cell:

Answer 23

metabolism

Question 24

The breaking down of complex molecules:

Answer 24

Catabolism

Question 25

The building up of complex molecules:

Answer 25

Anabolism

Question 26

Metabolic reactions are linked to/by…

Answer 26

biochemical pathways

Question 27

What makes a connected reaction?

Answer 27

When the product of the first reaction is the substrate for the second reaction

Question 28

What is a coupled reaction?

Answer 28

Two reactions that occur alongside each other, one of them usually as a byproduct

Question 29

Endothermic reactions..

Answer 29

Absorb heat/energy from the surroundings

Question 30

How is energy conserved in an endothermic reaction?

Answer 30

Heat from the surroundings is stored as kinetic and potential energy in the products

Question 31

For a reaction to occur inside a cell… (3 points)

Answer 31

It must be spontaneous, it just be exergonic, and the products must have less free energy than the reactants

Question 32

What type of energy do ATP molecules in a cell have?

Answer 32

Both kinetic and potential

Question 33

A cell polymerises 194 amino acids into a polypeptide. What type of metabolic reaction is this?

Answer 33

An anabolic pathway

Question 34

An example of a coupled reaction

Answer 34

glycolysis