set 10:

Question 1

[10.1] What is the key difference between aerobic respiration and fermentation?

Answer 1

Aerobic respiration uses an external electron acceptor (O2) and fully oxidizes substrates to CO2, producing much more ATP than fermentation.

Question 2

[10.1] What is an external vs internal electron acceptor? Give examples.

Answer 2

External: O2 in aerobic respiration. Internal: organic molecules like pyruvate in fermentation.

Question 3

[10.1] List the 5 stages of cellular respiration.

Answer 3

1) Glycolysis 2) Pyruvate oxidation 3) TCA cycle 4) Electron transport 5) Oxidative phosphorylation.

Question 4

[10.1] Why does aerobic respiration yield up to ~38 ATP per glucose?

Answer 4

Because electrons are transferred to O2 through the ETC, allowing extensive ATP generation via oxidative phosphorylation.

Question 5

[10.2] What allows the outer mitochondrial membrane to be permeable?

Answer 5

Porins that allow solutes up to ~5000 g/mol to pass.

Question 6

[10.2] Why is the intermembrane space continuous with the cytosol?

Answer 6

Because large porins in the outer membrane allow free diffusion of small molecules.

Question 7

[10.2] Why does the inner mitochondrial membrane have many cristae?

Answer 7

To increase surface area for electron transport and ATP synthesis.

Question 8

[10.2] Where do pyruvate oxidation and the TCA cycle occur?

Answer 8

In the mitochondrial matrix.

Question 9

[10.2] What is the FoF1 complex?

Answer 9

ATP synthase responsible for ATP production using the proton gradient.

Question 10

[10.3] How does pyruvate enter the mitochondrial matrix?

Answer 10

Via a symporter that transports pyruvate with H+.

Question 11

[10.3] What is pyruvate dehydrogenase (PDH)?

Answer 11

An enzyme complex that converts pyruvate into acetyl-CoA.

Question 12

[10.3] What products are generated during pyruvate oxidation per glucose?

Answer 12

2 acetyl-CoA, 2 NADH, and 2 CO2.

Question 13

[10.4] What enters and exits the TCA cycle per turn?

Answer 13

Enters: acetyl-CoA (2C). Exits: 2 CO2.

Question 14

[10.4] Which TCA steps produce NADH?

Answer 14

Isocitrate dehydrogenase, α-ketoglutarate dehydrogenase, malate dehydrogenase.

Question 15

[10.4] Which step produces FADH2?

Answer 15

Succinate dehydrogenase.

Question 16

[10.4] Which step produces GTP?

Answer 16

Succinyl-CoA synthetase via substrate-level phosphorylation.

Question 17

[10.4] How many NADH, FADH2, and GTP are produced per TCA turn?

Answer 17

3 NADH, 1 FADH2, 1 GTP.

Question 18

[10.5] What inhibits pyruvate dehydrogenase (PDH)?

Answer 18

High ATP, acetyl-CoA, and NADH.

Question 19

[10.5] What activates pyruvate dehydrogenase (PDH)?

Answer 19

High AMP, ADP, and NAD+.

Question 20

[10.5] Which TCA enzymes are inhibited by NADH?

Answer 20

Isocitrate dehydrogenase, α-ketoglutarate dehydrogenase, malate dehydrogenase.

Question 21

[10.6] What is the terminal electron acceptor in the ETC?

Answer 21

Oxygen (O2), forming water.

Question 22

[10.6] Why does NADH yield more ATP than FADH2?

Answer 22

Because NADH donates electrons to Complex I, pumping more protons.

Question 23

[10.7] Which electron carriers transfer both electrons and protons?

Answer 23

Flavoproteins and Coenzyme Q.

Question 24

[10.7] Which carriers transfer electrons only?

Answer 24

Iron-sulfur proteins and cytochromes.

Question 25

[10.7] What is unique about Coenzyme Q?

Answer 25

It is a non-protein, freely mobile carrier within the inner membrane.

Question 26

[10.8] What does a positive reduction potential indicate?

Answer 26

A strong tendency to gain electrons (strong oxidizing agent).

Question 27

[10.8] What determines if a redox reaction is spontaneous?

Answer 27

ΔE°′ > 0, which corresponds to ΔG°′ < 0.

Question 28

[10.8] What is the relationship between ΔG°′ and ΔE°′?

Answer 28

ΔG°′ = −nFΔE°′.

Question 29

[10.9] What is the electron path when NADH is the donor?

Answer 29

NADH → Complex I → CoQ → Complex III → Cyt C → Complex IV → O2.

Question 30

[10.10] What is the electron path when succinate is the donor?

Answer 30

Succinate → Complex II → CoQ → Complex III → Cyt C → Complex IV → O2.

Question 31

[10.10] How many protons are pumped per NADH?

Answer 31

10 H+.

Question 32

[10.10] How many protons are pumped per FADH2?

Answer 32

6 H+.

Question 33

[10.11] What is chemiosmosis?

Answer 33

The flow of protons down their electrochemical gradient through ATP synthase.

Question 34

[10.11] How many protons are required to synthesize 1 ATP?

Answer 34

~3 H+.

Question 35

[10.11] How many ATP are produced per NADH and FADH2?

Answer 35

NADH ≈ 3 ATP, FADH2 ≈ 2 ATP (BIO 201 convention).