Cellular Respiration Quiz
Questions: 16 · 10 minutes
1. A mammalian red blood cell lacks mitochondria. Under typical conditions, what can it obtain directly from one glucose molecule through glycolysis followed by lactate formation?
Carbon dioxide, water, and about 30 ATP
Acetyl-CoA, six carbon dioxide, and two ATP
Lactate and a net gain of two ATP
Ethanol, carbon dioxide, and four net ATP
2. An uncoupling molecule transports protons across the inner mitochondrial membrane without passing them through ATP synthase. Which outcome is most likely?
Electron transport may continue while ATP output from oxidative phosphorylation falls
Both electron transport and oxygen consumption must stop immediately
ATP production rises because the proton gradient becomes steeper
Glycolysis stops because uncoupling directly removes glucose
3. During intense exercise, a muscle cell's oxygen supply cannot meet demand. How does lactate fermentation help ATP production continue briefly?
It oxidizes NADH to regenerate the NAD+ required by glycolysis
It creates a mitochondrial proton gradient without oxygen
It allows lactate to serve as the final electron acceptor in the mitochondrial chain
It produces acetyl-CoA that immediately enters the citric acid cycle
4. In a eukaryotic cell, where does glycolysis occur?
In the mitochondrial matrix
In the intermembrane space
Along the inner mitochondrial membrane
In the cytosol
5. A plant leaf is kept in darkness but still has access to oxygen and stored sugars. Which statement best describes its cellular respiration?
Mitochondria can continue oxidizing stored sugars to produce ATP
Respiration occurs only in chloroplasts when photosynthesis is inactive
Respiration stops because plant cells can make ATP only in light
The leaf must switch entirely to alcoholic fermentation
6. What is the main energy-related function of cellular respiration?
To release all of glucose's energy at once as heat
To store sunlight directly in glucose without using electron carriers
To convert ATP into glucose for long-term energy storage
To transfer energy from fuel molecules into ATP through a series of controlled reactions
7. What is the net output of glycolysis from one glucose molecule?
Two acetyl-CoA, two ATP, and two FADH2
One pyruvate, four net ATP, and two NADH
Two pyruvate, two net ATP, and two NADH
Two pyruvate, no net ATP, and two NAD+
8. How does substrate-level phosphorylation differ from oxidative phosphorylation?
It requires oxygen to attach free phosphate directly to ADP
It uses an enzyme to transfer a phosphate group from a substrate directly to ADP
It depends on ATP synthase and a proton gradient
It occurs only during the electron transport chain
9. After glycolysis, both pyruvate molecules from one glucose are fully converted during pyruvate oxidation. How many acetyl-CoA molecules are produced?
Two
Three
Four
One
10. A functioning electron transport chain has built up protons in the mitochondrial intermembrane space. Through ATP synthase, how do most of these protons move?
From the matrix to the cytosol against their gradient
From the intermembrane space to the matrix down their electrochemical gradient
From the matrix to the intermembrane space down their gradient
From the cytosol to the intermembrane space by direct ATP hydrolysis
11. A substance makes the inner mitochondrial membrane freely permeable to protons. What is the most direct effect on ATP synthesis by ATP synthase?
ATP synthesis increases because protons reach the matrix more quickly
ATP synthesis decreases because the proton gradient dissipates
ATP synthesis stays constant because ATP synthase uses only NADH
ATP synthesis switches entirely to the citric acid cycle
12. What happens to oxygen at the end of the aerobic electron transport chain?
It donates electrons and becomes carbon dioxide
It is converted into acetyl-CoA
It pumps protons into the intermembrane space
It accepts electrons and protons, forming water
13. Scientists track carbon atoms from glucose during aerobic respiration. During which stages are those carbons released as carbon dioxide?
Glycolysis and chemiosmosis
Glycolysis and the electron transport chain
Pyruvate oxidation and the citric acid cycle
Fermentation and ATP synthase activity
14. A cell temporarily runs out of NAD+. Which glycolytic event is directly unable to proceed?
Transfer of a phosphate from ATP to glucose
Splitting one six-carbon sugar into two three-carbon molecules
Oxidation of glyceraldehyde-3-phosphate, which normally reduces NAD+ to NADH
Conversion of ATP into ADP by ATP synthase
15. A toxin blocks complex IV of the mitochondrial electron transport chain. What is the most likely immediate consequence?
Oxygen accepts electrons at complex I instead
The citric acid cycle begins producing oxygen
ATP synthase starts pumping protons out of the matrix
Electron flow backs up, leaving many upstream carriers in a reduced state
16. When oxygen is unavailable, what is the main benefit of fermentation to a cell performing glycolysis?
It produces more ATP than aerobic respiration
It regenerates NAD+ so glycolysis can continue
It sends electrons to oxygen through an alternate pathway
It converts pyruvate directly into acetyl-CoA