Cellular Respiration Worksheet with questions on the phases, ATP production, and key processes of cellular respiration.
A worksheet titled "Cellular Respiration Worksheet" with 15 questions about the phases, locations, and processes of cellular respiration, including glycolysis, the Krebs cycle, and the electron transport chain.
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Step-by-step solution for: Solved Cellular Respiration Worksheet 1. What are the 3 | Chegg.com
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Show Answer Key & Explanations
Step-by-step solution for: Solved Cellular Respiration Worksheet 1. What are the 3 | Chegg.com
Let’s go through each question one by one, step by step. I’ll explain the answers clearly so you understand why they’re correct.
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1. What are the 3 phases of the cellular respiration process?
Cellular respiration has three main stages:
- First, glycolysis — breaks down glucose in the cytoplasm.
- Second, the Krebs cycle (Citric Acid Cycle) — happens in the mitochondria and finishes breaking down fuel molecules.
- Third, the electron transport chain — also in the mitochondria, makes most of the ATP using oxygen.
✔ Final Answer for #1:
Glycolysis, Krebs cycle (or Citric Acid Cycle), and Electron Transport Chain
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2. Where in the cell does glycolysis occur?
Glycolysis doesn’t need any special organelles — it happens right in the fluid part of the cell called the cytoplasm.
✔ Final Answer for #2:
Cytoplasm
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3. Where does the Krebs cycle occur?
The Krebs cycle takes place inside the mitochondria, specifically in the inner space called the matrix.
✔ Final Answer for #3:
Mitochondrial matrix (or just “mitochondria”)
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4. Where does the electron transport part occur?
This happens on the inner membrane of the mitochondria — where all the protein complexes are lined up to pass electrons and make ATP.
✔ Final Answer for #4:
Inner mitochondrial membrane
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5. How many ATP (net) are made in glycolysis?
In glycolysis, you use 2 ATP to start, but you make 4 ATP total → so net gain is 2 ATP.
✔ Final Answer for #5:
2 ATP
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6. How many ATP are made in the Krebs cycle?
For each glucose molecule, the Krebs cycle runs twice (once per pyruvate). Each turn makes 1 ATP → so total = 2 ATP per glucose.
✔ Final Answer for #6:
2 ATP
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7. How many ATP are made in the electron transport part?
This is where most ATP is made! From NADH and FADH₂ produced earlier, we get about 32–34 ATP total from this stage. But since textbooks often round or simplify, a common answer is 32 ATP (sometimes 34).
We’ll go with the standard textbook number: 32 ATP
✔ Final Answer for #7:
32 ATP
*(Note: Some sources say 34 — both are acceptable depending on how you count proton leaks, etc. But 32 is commonly taught.)*
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8. In which phase is carbon dioxide made?
CO₂ is released when carbon atoms are removed during the breakdown of pyruvate and in the Krebs cycle. So mostly in the Krebs cycle (and also during the link reaction before it).
✔ Final Answer for #8:
Krebs cycle (and pyruvate oxidation)
But if only one answer is expected: Krebs cycle
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9. In which phase is water made?
Water is formed at the very end of the electron transport chain when oxygen accepts electrons and combines with hydrogen ions.
✔ Final Answer for #9:
Electron Transport Chain
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10. In which phase is oxygen a substrate?
Oxygen is used as the final electron acceptor in the electron transport chain. Without it, the whole chain stops.
✔ Final Answer for #10:
Electron Transport Chain
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11. In which phase is glucose a substrate?
Glucose is broken down in the first step — glycolysis. That’s its only direct role.
✔ Final Answer for #11:
Glycolysis
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12. On average, how many ATP can be made from each NADH during ETC?
Each NADH gives enough energy to make about 3 ATP (in older models; newer research says ~2.5, but schools still teach 3).
✔ Final Answer for #12:
3 ATP
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13. On average, how many ATP can be made from each FADH₂ during ETC?
FADH₂ enters later in the chain, so it produces less energy → about 2 ATP per FADH₂.
✔ Final Answer for #13:
2 ATP
---
14. What would happen if an enzyme were missing or defective?
Enzymes speed up every step. If one is missing, that step can’t happen → the whole process slows down or stops completely. Like a traffic jam in a factory line.
✔ Final Answer for #14:
The process would slow down or stop because enzymes are needed to catalyze each step.
---
15. What happens to high-energy electrons (and H⁺) held by NADH if there’s no O₂?
Without oxygen, the electron transport chain can’t run. So NADH can’t drop off its electrons. The cell switches to fermentation (like lactic acid or alcohol fermentation) to recycle NADH back to NAD⁺ so glycolysis can keep going.
✔ Final Answer for #15:
They are used in fermentation to regenerate NAD⁺ so glycolysis can continue without oxygen.
---
## ✔ FINAL ANSWERS (Numbered):
1. Glycolysis, Krebs cycle (Citric Acid Cycle), Electron Transport Chain
2. Cytoplasm
3. Mitochondrial matrix (or mitochondria)
4. Inner mitochondrial membrane
5. 2 ATP
6. 2 ATP
7. 32 ATP
8. Krebs cycle
9. Electron Transport Chain
10. Electron Transport Chain
11. Glycolysis
12. 3 ATP
13. 2 ATP
14. The process would slow down or stop because enzymes are needed to catalyze each step.
15. They are used in fermentation to regenerate NAD⁺ so glycolysis can continue without oxygen.
---
1. What are the 3 phases of the cellular respiration process?
Cellular respiration has three main stages:
- First, glycolysis — breaks down glucose in the cytoplasm.
- Second, the Krebs cycle (Citric Acid Cycle) — happens in the mitochondria and finishes breaking down fuel molecules.
- Third, the electron transport chain — also in the mitochondria, makes most of the ATP using oxygen.
✔ Final Answer for #1:
Glycolysis, Krebs cycle (or Citric Acid Cycle), and Electron Transport Chain
---
2. Where in the cell does glycolysis occur?
Glycolysis doesn’t need any special organelles — it happens right in the fluid part of the cell called the cytoplasm.
✔ Final Answer for #2:
Cytoplasm
---
3. Where does the Krebs cycle occur?
The Krebs cycle takes place inside the mitochondria, specifically in the inner space called the matrix.
✔ Final Answer for #3:
Mitochondrial matrix (or just “mitochondria”)
---
4. Where does the electron transport part occur?
This happens on the inner membrane of the mitochondria — where all the protein complexes are lined up to pass electrons and make ATP.
✔ Final Answer for #4:
Inner mitochondrial membrane
---
5. How many ATP (net) are made in glycolysis?
In glycolysis, you use 2 ATP to start, but you make 4 ATP total → so net gain is 2 ATP.
✔ Final Answer for #5:
2 ATP
---
6. How many ATP are made in the Krebs cycle?
For each glucose molecule, the Krebs cycle runs twice (once per pyruvate). Each turn makes 1 ATP → so total = 2 ATP per glucose.
✔ Final Answer for #6:
2 ATP
---
7. How many ATP are made in the electron transport part?
This is where most ATP is made! From NADH and FADH₂ produced earlier, we get about 32–34 ATP total from this stage. But since textbooks often round or simplify, a common answer is 32 ATP (sometimes 34).
We’ll go with the standard textbook number: 32 ATP
✔ Final Answer for #7:
32 ATP
*(Note: Some sources say 34 — both are acceptable depending on how you count proton leaks, etc. But 32 is commonly taught.)*
---
8. In which phase is carbon dioxide made?
CO₂ is released when carbon atoms are removed during the breakdown of pyruvate and in the Krebs cycle. So mostly in the Krebs cycle (and also during the link reaction before it).
✔ Final Answer for #8:
Krebs cycle (and pyruvate oxidation)
But if only one answer is expected: Krebs cycle
---
9. In which phase is water made?
Water is formed at the very end of the electron transport chain when oxygen accepts electrons and combines with hydrogen ions.
✔ Final Answer for #9:
Electron Transport Chain
---
10. In which phase is oxygen a substrate?
Oxygen is used as the final electron acceptor in the electron transport chain. Without it, the whole chain stops.
✔ Final Answer for #10:
Electron Transport Chain
---
11. In which phase is glucose a substrate?
Glucose is broken down in the first step — glycolysis. That’s its only direct role.
✔ Final Answer for #11:
Glycolysis
---
12. On average, how many ATP can be made from each NADH during ETC?
Each NADH gives enough energy to make about 3 ATP (in older models; newer research says ~2.5, but schools still teach 3).
✔ Final Answer for #12:
3 ATP
---
13. On average, how many ATP can be made from each FADH₂ during ETC?
FADH₂ enters later in the chain, so it produces less energy → about 2 ATP per FADH₂.
✔ Final Answer for #13:
2 ATP
---
14. What would happen if an enzyme were missing or defective?
Enzymes speed up every step. If one is missing, that step can’t happen → the whole process slows down or stops completely. Like a traffic jam in a factory line.
✔ Final Answer for #14:
The process would slow down or stop because enzymes are needed to catalyze each step.
---
15. What happens to high-energy electrons (and H⁺) held by NADH if there’s no O₂?
Without oxygen, the electron transport chain can’t run. So NADH can’t drop off its electrons. The cell switches to fermentation (like lactic acid or alcohol fermentation) to recycle NADH back to NAD⁺ so glycolysis can keep going.
✔ Final Answer for #15:
They are used in fermentation to regenerate NAD⁺ so glycolysis can continue without oxygen.
---
## ✔ FINAL ANSWERS (Numbered):
1. Glycolysis, Krebs cycle (Citric Acid Cycle), Electron Transport Chain
2. Cytoplasm
3. Mitochondrial matrix (or mitochondria)
4. Inner mitochondrial membrane
5. 2 ATP
6. 2 ATP
7. 32 ATP
8. Krebs cycle
9. Electron Transport Chain
10. Electron Transport Chain
11. Glycolysis
12. 3 ATP
13. 2 ATP
14. The process would slow down or stop because enzymes are needed to catalyze each step.
15. They are used in fermentation to regenerate NAD⁺ so glycolysis can continue without oxygen.
Parent Tip: Review the logic above to help your child master the concept of respiration worksheet.
