Biology Practice Test: Cellular Respiration
- Cellular Respiration
- 10 questions
- 13 minutes
This test follows glucose through glycolysis, the Krebs cycle and the electron transport chain. Tip: track where each stage happens and what it hands to the next stage; most of the ATP is made at the very end.
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Question 1
Which equation summarizes aerobic cellular respiration?
Correct answer: D
Aerobic respiration uses glucose and oxygen and releases carbon dioxide, water and energy. The second equation is photosynthesis, and the third is alcoholic fermentation.
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Question 2
Glycolysis splits one molecule of glucose into two molecules of which compound?
Correct answer: C
Glycolysis ends with two molecules of pyruvate. Acetyl-CoA is made from pyruvate later, inside the mitochondrion, and lactic acid forms only during fermentation.
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Question 3
What is the main job of NADH and FADH2 in cellular respiration?
Correct answer: D
NADH and FADH2 are electron carriers. They pick up electrons in glycolysis and the Krebs cycle and deliver them to the electron transport chain, where most ATP is made.
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Question 4
Where in the cell is the electron transport chain of aerobic respiration located?
Correct answer: B
The proteins of the electron transport chain and ATP synthase sit in the inner membrane, which is folded into cristae. The matrix is where the Krebs cycle runs.
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Question 5
Inside a mitochondrion, ATP synthase makes ATP. What directly drives ATP synthase?
Correct answer: A
The electron transport chain pumps hydrogen ions out of the matrix. Their flow back in through ATP synthase turns the enzyme, which joins ADP and phosphate into ATP.
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Question 6
Much of the carbon dioxide you breathe out is produced during which stage(s) of cellular respiration?
Correct answer: A
Carbon atoms from glucose leave as CO2 when pyruvate is converted to acetyl-CoA and during the Krebs cycle. The electron transport chain uses oxygen and makes water, not CO2.
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Question 7
A student measures oxygen use in three sealed tubes: one with germinating pea seeds, one with dry pea seeds and one with glass beads of the same volume. Which result is expected?
Correct answer: A
Germinating seeds are growing and respire quickly, so they use the most oxygen. Dry seeds are dormant with very low respiration, and glass beads are not alive; they only control for changes not caused by living cells.
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Question 8
Cyanide is a poison that blocks the last protein of the electron transport chain, so electrons can no longer be passed to oxygen. What is the effect on the cell?
Correct answer: C
If electrons cannot reach oxygen, the whole chain backs up and the hydrogen ion gradient is no longer built. Without it, ATP synthase makes almost no ATP, leaving only the small yield from glycolysis.
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Question 9
When a muscle cell uses ATP to contract, what happens to the ATP molecule?
Correct answer: B
Energy is released when the bond to the last phosphate group is broken, turning ATP into ADP and a free phosphate. Cellular respiration later adds the phosphate back.
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Question 10
Which statement about cellular respiration in plants is correct?
Correct answer: B
Plant cells have mitochondria and need ATP all the time, so they respire day and night. During the day photosynthesis is usually faster, which hides the respiration in gas measurements.
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