Exam 4 Study Guide

Question 1

What does the First Law of Thermodynamics state?

Answer 1

Energy cannot be created or destroyed—only transformed

Question 2

What does the Second Law of Thermodynamics state?

Answer 2

Spontaneous processes increase the total entropy of the universe

Question 3

How does life obey the Second Law of Thermodynamics?

Answer 3

Cells increase disorder elsewhere (e.g., releasing heat) while maintaining internal order

Question 4

What is entropy?

Answer 4

A measure of disorder; higher entropy = more spontaneous

Question 5

What is an endergonic reaction?

Answer 5

A reaction with a positive ΔG that requires energy input (non-spontaneous)

Question 6

What is an exergonic reaction?

Answer 6

A reaction with a negative ΔG that releases energy (spontaneous)

Question 7

How do cells drive unfavorable reactions?

Answer 7

By coupling them to favorable reactions like ATP hydrolysis

Question 8

What trend makes a reaction more thermodynamically favorable?

Answer 8

Increased entropy, lower energy products, or electron flow toward electronegative atoms

Question 9

Why is ATP important?

Answer 9

It stores and transfers energy for chemical, mechanical, and transport work

Question 10

What makes ATP hydrolysis exergonic?

Answer 10

It releases a phosphate, increases entropy, and produces stable products

Question 11

What are examples of ATP-dependent biological work?

Answer 11

Active transport, muscle contraction, polymer synthesis

Question 12

What is diffusion?

Answer 12

Movement of particles from high → low concentration (spontaneous)

Question 13

What is a concentration gradient?

Answer 13

A difference in concentration that stores potential energy

Question 14

What is passive transport?

Answer 14

Movement down a concentration gradient without energy

Question 15

What is active transport?

Answer 15

Movement up a gradient requiring ATP or stored energy

Question 16

Which direction is energetically “down” a gradient?

Answer 16

From high → low concentration (favorable)

Question 17

What does thermodynamics tell you about a reaction?

Answer 17

Whether it can occur (ΔG)

Question 18

What does kinetics tell you about a reaction?

Answer 18

How fast it occurs

Question 19

Do enzymes change ΔG?

Answer 19

No—they only lower activation energy

Question 20

What does it mean to catalyze a reaction?

Answer 20

To lower its activation energy and increase its rate

Question 21

How do enzymes work?

Answer 21

They stabilize the transition state, lowering EA

Question 22

What is feedback inhibition in metabolism?

Answer 22

A pathway’s end product inhibits an early enzyme to regulate flow

Question 23

What does the Law of Conservation of Matter mean for metabolism?

Answer 23

Atoms must be accounted for; molecules break and rearrange but don’t disappear

Question 24

What does “trace metabolites” mean?

Answer 24

Follow carbon atoms through glycolysis, CAC, etc

Question 25

What is “interconnectedness” in metabolism?

Answer 25

Pathways share intermediates and regulate each other

Question 26

What is metabolic “compartmentalization”?

Answer 26

Reactions occur in specific cell regions (cytosol vs mitochondria)

Question 27

What is metabolic regulation/flexibility?

Answer 27

Adjusting pathway activity based on energy needs and environment

Question 28

What is catabolism?

Answer 28

Energy-releasing breakdown of molecules (favorable)

Question 29

What is anabolism?

Answer 29

Building molecules using energy (unfavorable)

Question 30

What is oxidation?

Answer 30

Loss of electrons

Question 31

What is reduction?

Answer 31

Gain of electrons

Question 32

How does electronegativity relate to redox favorability?

Answer 32

Electrons flow spontaneously toward more electronegative atoms

Question 33

Why is redox coupling important in glycolysis?

Answer 33

It drives ATP-producing steps by linking them to favorable electron transfer

Question 34

Where does glycolysis occur?

Answer 34

In the cytosol

Question 35

Why is glycolysis considered ancient?

Answer 35

It evolved before oxygen was abundant; used by all organisms

Question 36

What are the two main phases of glycolysis?

Answer 36

Energy investment and energy payoff

Question 37

What is the role of NAD⁺ in glycolysis?

Answer 37

It accepts electrons, forming NADH

Question 38

Why is pyruvate a “decision point”?

Answer 38

It can go to fermentation, respiration, or biosynthesis

Question 39

How is glycolysis regulated?

Answer 39

PFK is inhibited by ATP (feedback)

Question 40

Where does the citric acid cycle take place?

Answer 40

Mitochondrial matrix

Question 41

What enters the CAC?

Answer 41

Acetyl-CoA

Question 42

Why is it called a cycle?

Answer 42

It regenerates oxaloacetate each round

Question 43

What does the CAC produce?

Answer 43

NADH, FADH₂, CO₂, and some ATP/GTP

Question 44

Why is the CAC central to metabolism?

Answer 44

Many molecules feed into and out of it (interconnectedness)

Question 45

Where is the ETC located?

Answer 45

Inner mitochondrial membrane

Question 46

What is the main function of the ETC?

Answer 46

Transfer electrons from NADH/FADH₂ to oxygen while pumping protons

Question 47

Why is oxygen the final electron acceptor?

Answer 47

It is highly electronegative and forms water when reduced

Question 48

What creates the proton gradient?

Answer 48

Proton pumping by ETC complexes I, III, and IV

Question 49

How does ATP synthase work?

Answer 49

Protons flow through it, causing rotation that synthesizes ATP

Question 49

What is chemiosmosis?

Answer 49

Using a proton gradient to drive ATP synthesis

Question 50

What is oxidative phosphorylation?

Answer 50

ATP production powered by the ETC + ATP synthase

Question 51

What is the overall energy flow from food to ATP?

Answer 51

Chemical bonds → electrons → ETC → proton gradient → ATP

Question 52

How do glycolysis, CAC, and ETC connect?

Answer 52

Glycolysis & CAC generate electron carriers → ETC uses them → ATP synthase makes ATP