step 2: krebs cycle
16. where in the cell does the krebs cycle occur (be specific)?

17. krebs cycle can occur with or without oxygen. true false
18. what are the end products of the krebs cycle (per 1 sugar molecule) and how many of each?
#______ atp #______ carbon dioxide #______ nadh #______fadh₂
step 3: electron transport chain

19. where in the cell does the etc occur (be specific)?

20. the etc can occur with or without oxygen. true false

Question

step 2: krebs cycle
16. where in the cell does the krebs cycle occur (be specific)?

17. krebs cycle can occur with or without oxygen.  true false
18. what are the end products of the krebs cycle (per 1 sugar molecule) and how many of each?
 #______ atp #______ carbon dioxide  #______ nadh  #______fadh₂
step 3: electron transport chain

19. where in the cell does the etc occur (be specific)?

20. the etc can occur with or without oxygen. true false

Accepted Answer

### Question 16
# Brief Explanations:
The Krebs cycle (also known as the citric acid cycle) occurs in the matrix of the mitochondria in eukaryotic cells. Mitochondria are the powerhouses of the cell, and the matrix is the innermost compartment of the mitochondrion, where the enzymes for the Krebs cycle are located.
# Answer:
Matrix of the mitochondria (in eukaryotic cells)

### Question 17
# Brief Explanations:
The Krebs cycle is an aerobic process, meaning it requires oxygen to occur. It is part of cellular respiration, and oxygen is needed as the final electron acceptor in the overall process. Without oxygen, the Krebs cycle cannot continue because the electron transport chain (which is linked to the Krebs cycle) would back up, and the necessary cofactors would not be regenerated. So the statement "Krebs cycle can occur with or without oxygen" is false.
# Answer:
FALSE

### Question 18
# Brief Explanations:
For one glucose molecule (which is the sugar molecule typically referred to in cellular respiration), the Krebs cycle runs twice (because glycolysis produces two pyruvate molecules, each entering the Krebs cycle). But when considering per 1 sugar molecule (glucose), the end products per glucose (after two rounds of the Krebs cycle) are: 2 ATP (or 1 ATP per round, so 2 for two rounds), 6 Carbon Dioxide (3 per round), 10 NADH (5 per round), and 2 FADH₂ (1 per round). Wait, but if we consider per 1 pyruvate (which is derived from 1/2 glucose), then per pyruvate (1 sugar molecule equivalent in terms of entering the Krebs cycle), the products would be 1 ATP, 3 Carbon Dioxide, 4 NADH, and 1 FADH₂? Wait, no, let's clarify. The standard is: for one glucose molecule, glycolysis produces 2 pyruvate. Each pyruvate enters the Krebs cycle, so the Krebs cycle occurs twice per glucose. So per glucose (1 sugar molecule), the Krebs cycle produces: 2 ATP (substrate - level phosphorylation, 1 per round), 6 CO₂ (3 per round), 10 NADH (5 per round), and 2 FADH₂ (1 per round). But if the question is per 1 sugar molecule (assuming 1 pyruvate, which is from 1/2 glucose), then per pyruvate (1 sugar - like unit entering the Krebs cycle), the products are 1 ATP, 3 CO₂, 4 NADH, and 1 FADH₂? Wait, no, the correct breakdown per glucose (1 sugar molecule) is:
- ATP: 2 (from substrate - level phosphorylation in the Krebs cycle, 1 per round, 2 rounds)
- Carbon Dioxide: 6 (3 per round, 2 rounds)
- NADH: 10 (5 per round, 2 rounds)
- FADH₂: 2 (1 per round, 2 rounds)

But maybe the question is considering per 1 pyruvate (so per 1/2 glucose). Let's check the standard. The Krebs cycle: for each acetyl - CoA (which is what pyruvate is converted to) that enters the cycle, the products are 1 ATP, 3 CO₂, 4 NADH, and 1 FADH₂. Since one glucose produces two acetyl - CoA, for one glucose (1 sugar molecule), it's 2 ATP, 6 CO₂, 10 NADH, 2 FADH₂. So if the question is per 1 sugar molecule (glucose), the answers are:
# ATP: 2
# Carbon Dioxide: 6
# NADH: 10
# FADH₂: 2

But maybe the question is considering per pyruvate (1 sugar - derived molecule entering the Krebs cycle). In that case, per pyruvate (which is from 1/2 glucose), the products are 1 ATP, 3 CO₂, 4 NADH, 1 FADH₂. However, the more common way is to consider per glucose. Let's confirm the standard values:
- ATP: 2 (total from Krebs cycle per glucose)
- CO₂: 6 (total from Krebs cycle per glucose)
- NADH: 10 (total from Krebs cycle per glucose)
- FADH₂: 2 (total from Krebs cycle per glucose)

So filling in the blanks:
# ATP: 2
# Carbon Dioxide: 6
# NADH: 10
# FADH₂: 2
# Brief Explanations:
For one glucose molecule (the sugar molecule), the Krebs cycle runs twice (because glycolysis produces two pyruvate molecules, each converted to acetyl - CoA and entering the Krebs cycle). In each round of the Krebs cycle (per acetyl - CoA), the products are 1 ATP, 3 CO₂, 4 NADH, and 1 FADH₂. So for two rounds (per glucose):
- ATP: 2 (1 per round × 2 rounds)
- Carbon Dioxide: 6 (3 per round × 2 rounds)
- NADH: 10 (5 per round? Wait, no, 4 per round? Wait, no, let's re - calculate. Each acetyl - CoA in the Krebs cycle:
    - 3 NAD⁺ are reduced to NADH (so 3 NADH per round)
    - 1 FAD is reduced to FADH₂ (1 FADH₂ per round)
    - 1 ATP is produced (substrate - level phosphorylation)
    - 2 CO₂ are released? Wait, no, I think I made a mistake earlier. Let's use the correct stoichiometry:
The Krebs cycle (citric acid cycle) for one acetyl - CoA:
- 3 NADH are produced (from isocitrate to α - ketoglutarate, α - ketoglutarate to succinyl - CoA, and malate to oxaloacetate? Wait, no, the steps are:
1. Citrate to isocitrate: no NADH.
2. Isocitrate to α - ketoglutarate: produces 1 NADH.
3. α - ketoglutarate to succinyl - CoA: produces 1 NADH.
4. Succinyl - CoA to succinate: produces 1 ATP (or GTP).
5. Succinate to fumarate: produces 1 FADH₂.
6. Fumarate to malate: no NADH.
7. Malate to oxaloacetate: produces 1 NADH.

Wait, so that's 3 NADH, 1 FADH₂, 1 ATP, and 2 CO₂ (released at steps 2 and 3). Oh! I see, I had the CO₂ wrong earlier. So per acetyl - CoA, the Krebs cycle produces 3 NADH, 1 FADH₂, 1 ATP, and 2 CO₂. Then, for two acetyl - CoA (per glucose), it's 6 NADH, 2 FADH₂, 2 ATP, and 4 CO₂? No, this is getting confusing. Let's refer to the standard textbook values:
The net yield of the Krebs cycle per glucose molecule (which is broken down into two acetyl - CoA molecules) is:
- 2 ATP (or 2 GTP)
- 6 NADH
- 2 FADH₂
- 4 CO₂

Ah, there we go. I had the CO₂ number wrong earlier. So the correct values per glucose (1 sugar molecule) are:
- ATP: 2
- Carbon Dioxide: 4
- NADH: 6
- FADH₂: 2

Wait, now I'm really confused. Let's check a reliable source. According to the standard cellular respiration pathway:
- Glycolysis: 1 glucose → 2 pyruvate, 2 ATP, 2 NADH.
- Pyruvate oxidation: 2 pyruvate → 2 acetyl - CoA, 2 NADH, 2 CO₂.
- Krebs cycle: 2 acetyl - CoA → 2 ATP, 6 NADH, 2 FADH₂, 4 CO₂.

Ah! So the Krebs cycle (for 2 acetyl - CoA, i.e., per glucose) produces 2 ATP, 4 CO₂, 6 NADH, and 2 FADH₂. So if the question is per 1 sugar molecule (glucose), then:
# ATP: 2
# Carbon Dioxide: 4
# NADH: 6
# FADH₂: 2

I think my earlier mistake was in the number of CO₂ molecules. The pyruvate oxidation (before the Krebs cycle) produces 2 CO₂ per glucose, and the Krebs cycle produces 4 CO₂ per glucose. So in total, per glucose, 6 CO₂ are produced (2 from pyruvate oxidation, 4 from Krebs cycle). But the question is about the end products of the Krebs cycle, so only the CO₂ produced in the Krebs cycle, which is 4 per glucose (2 per acetyl - CoA).

So to summarize, for the Krebs cycle (per 1 glucose molecule, which is the sugar molecule):
- ATP: 2
- Carbon Dioxide: 4
- NADH: 6
- FADH₂: 2

So the blanks should be filled as:
# ATP: 2
# Carbon Dioxide: 4
# NADH: 6
# FADH₂: 2
# Answer:
# ATP: 2
# Carbon Dioxide: 4
# NADH: 6
# FADH₂: 2

### Question 19
# Brief Explanations:
The Electron Transport Chain (ETC) occurs in the inner mitochondrial membrane in eukaryotic cells. The inner mitochondrial membrane contains the protein complexes (Complex I, II, III, IV) and ATP synthase that are involved in the ETC. In prokaryotic cells, the ETC occurs in the plasma membrane. But for eukaryotic cells, the specific location is the inner mitochondrial membrane.
# Answer:
Inner mitochondrial membrane (in eukaryotic cells); Plasma membrane (in prokaryotic cells)

### Question 20
# Brief Explanations:
The Electron Transport Chain (ETC) is an aerobic process. Oxygen is the final electron acceptor in the ETC. Without oxygen, the electrons cannot be passed down the chain, and the process will stop. So the statement "The ETC can occur with or without oxygen" is false.
# Answer:
FALSE

Sovi.AI - AI Math Tutor

QUESTION IMAGE

Question

Explanation:

Question 16

ATP: 2

Carbon Dioxide: 6

NADH: 10

FADH₂: 2

ATP: 2

Carbon Dioxide: 6

NADH: 10

FADH₂: 2

Answer:

Question 17