C1.2 Cell respiration
Practice exam-style IB Biology questions for Cell respiration, aligned with the syllabus and grouped by topic.
Question 1
What is ATP?
A.
A lipid containing glycerol, fatty acids and three phosphate groups
B.
A nucleotide containing adenine, ribose and three phosphate groups
C.
A carbohydrate containing glucose, fructose and phosphate groups
D.
A protein containing amino acids and a terminal phosphate group
Question 2
What cellular process is directly supplied with energy from ATP hydrolysis?
A.
Osmosis of water through aquaporins down a water potential gradient
B.
Movement of sodium ions against their concentration gradient by a pump protein
C.
Diffusion of oxygen through the phospholipid bilayer into a cell
D.
Movement of carbon dioxide out of a respiring cell by diffusion
Question 3
What occurs during hydrolysis of ATP?
A.
Water is produced when ADP and phosphate join, releasing energy
B.
Hydrogen is removed from ATP and accepted by NAD
C.
Water is used to split ATP into ADP and inorganic phosphate, releasing energy
D.
Oxygen is used to split ATP into AMP and carbon dioxide
Question 4
What is the waste product of anaerobic cell respiration in human muscle cells?
A.
Water
B.
Ethanol
C.
Carbon dioxide
D.
Lactate
Question 5
State the full name of ATP.
[1]
Outline one property of ATP that makes it suitable as an energy currency in cells.
[1]
Question 6
What best distinguishes cell respiration from gas exchange?
A.
Cell respiration moves oxygen into the lungs; gas exchange produces ATP in mitochondria
B.
Cell respiration releases energy from carbon compounds to synthesize ATP; gas exchange moves respiratory gases between a cell or organism and its surroundings
C.
Cell respiration absorbs carbon dioxide; gas exchange oxidizes glucose
D.
Cell respiration occurs only in animals; gas exchange occurs only in plants
Question 7
A respirometer shows that 0.36 cm³ of oxygen is absorbed by germinating seeds in 6.0 min. What is the rate of oxygen uptake?
A.
0.060 cm³ min⁻¹
B.
0.17 cm³ min⁻¹
C.
6.36 cm³ min⁻¹
D.
2.16 cm³ min⁻¹
Question 8
What is the simple word equation for aerobic respiration in humans when glucose is the substrate?
A.
glucose + oxygen → carbon dioxide + water
B.
glucose + carbon dioxide → ethanol + oxygen
C.
glucose → lactate
D.
carbon dioxide + water → glucose + oxygen
Question 9
What happens to NAD during dehydrogenation of a respiratory substrate?
A.
NAD accepts oxygen and is oxidized
B.
NAD loses carbon dioxide and is phosphorylated
C.
NAD accepts hydrogen and is reduced
D.
NAD loses hydrogen and is reduced
Question 10
What is the net yield of glycolysis from one molecule of glucose?
A.
One pyruvate, four ATP and two oxidized NAD
B.
Two acetyl-CoA, two ATP and carbon dioxide
C.
Two lactate, no ATP and two reduced NAD
D.
Two pyruvate, two ATP and two reduced NAD
Question 11
Why is pyruvate converted to lactate in anaerobic respiration in human cells?
A.
To convert two-carbon acetyl groups into carbon dioxide
B.
To produce additional ATP directly from lactate formation
C.
To oxidize reduced NAD and regenerate NAD for glycolysis
D.
To provide oxygen as the terminal electron acceptor
Question 12
State one example of cellular movement that requires ATP.
[1]
Outline how ATP supplies energy for active transport.
[1]
Question 13
Define hydrolysis.
[1]
Distinguish between ATP hydrolysis and ATP synthesis in terms of energy transfer.
[1]
Question 14
Define cell respiration.
[1]
Distinguish cell respiration from gas exchange.
[1]
Question 15
Define oxidation in terms of electrons.
[1]
Explain why removal of hydrogen from a respiratory substrate is oxidation.
[1]
Question 16
A student used a respirometer to investigate oxygen uptake by germinating mung beans at a constant temperature.
Using the graph, calculate the mean rate of oxygen uptake over the time interval shown.
[1]
Describe the trend in oxygen uptake over time.
[1]
Suggest why potassium hydroxide was included in the respirometer.
[1]
Question 17
A fermenting suspension of yeast and glucose lost mass as carbon dioxide escaped.
Using the graph, calculate the rate of mass loss during the initial straight-line section.
[1]
Suggest why mass loss can be used as an indirect measure of respiration rate in this investigation.
[1]
Question 18
In a respirometer, potassium hydroxide is placed in the sealed tube with respiring organisms. What is its role?
A.
Absorb carbon dioxide so the change in gas volume mainly indicates oxygen uptake
B.
Supply oxygen so aerobic respiration can continue at a constant rate
C.
Provide glucose as a respiratory substrate for the organisms
D.
Release heat to keep the organisms at a constant temperature
Question 19
What are the products formed from pyruvate during anaerobic respiration in yeast?
A.
Acetyl-CoA and oxygen
B.
Lactate and water
C.
Ethanol and carbon dioxide
D.
Citrate and reduced NAD
Question 20
What occurs in the link reaction in aerobic respiration?
A.
Oxygen accepts electrons and protons to form metabolic water
B.
Pyruvate is decarboxylated and oxidized to form an acetyl group carried by coenzyme A
C.
Glucose is phosphorylated and split into two three-carbon sugars
D.
Citrate is converted back to oxaloacetate with release of ATP
Question 21
In the Krebs cycle, what is formed when an acetyl group combines with oxaloacetate?
A.
Ethanal, a two-carbon compound
B.
Pyruvate, a three-carbon compound
C.
Lactate, a three-carbon compound
D.
Citrate, a six-carbon compound
Question 22
How does ATP synthase produce ATP in mitochondria?
A.
It splits glucose into pyruvate and transfers phosphate to NAD
B.
It couples proton diffusion from the intermembrane space to the matrix with phosphorylation of ADP
C.
It pumps electrons from the matrix to oxygen and hydrolyses ATP
D.
It transports lactate into mitochondria to regenerate oxygen
Question 23
What explains the greater energy yield per gram from lipids compared with carbohydrates?
A.
Lipids can be converted directly into lactate without using enzymes
B.
Lipids contain less oxygen and more oxidizable carbon and hydrogen
C.
Lipids enter glycolysis earlier than glucose molecules
D.
Lipids contain more peptide bonds than carbohydrates
Question 24
Compare aerobic and anaerobic respiration in human cells.
Give the word equation for anaerobic respiration using glucose.
[1]
Give two differences between aerobic and anaerobic respiration in humans other than the equation.
[1]
State where anaerobic respiration occurs in human cells.
[1]
Question 25
A student measures oxygen uptake by woodlice in a respirometer. The gas volume falls from 1.20 cm³ to 0.84 cm³ in 12 min.
Calculate the volume of oxygen taken up.
[1]
Calculate the rate of oxygen uptake in cm³ min⁻¹.
[1]
State one variable that should be controlled.
[1]
Question 26
A respirometer has two matched tubes: one containing germinating seeds and one containing glass beads of the same volume.
State the purpose of the tube containing glass beads.
[1]
Explain why temperature should be kept constant during the investigation.
[1]
Question 27
Outline glycolysis.
State the cellular location of glycolysis.
[1]
Outline the sequence of processes in glycolysis leading from glucose to pyruvate.
[1]
Question 28
In human anaerobic respiration, pyruvate is converted to lactate.
State the molecule that donates hydrogen to pyruvate.
[1]
Explain how this conversion allows ATP production to continue.
[1]
Question 29
Compare anaerobic respiration in humans and yeast.
State one feature common to both pathways.
[1]
State the final products in yeast.
[1]
Explain one use of yeast anaerobic respiration in baking or brewing.
[1]
Question 30
The link reaction connects glycolysis with the Krebs cycle.
State where the link reaction occurs in eukaryotic cells.
[1]
Outline the changes to pyruvate during the link reaction.
[1]
Question 31
A class compared respiration rates of germinating seeds at different temperatures using oxygen uptake.
Identify the temperature at which oxygen uptake rate was greatest.
[1]
Describe the effect of temperature on respiration rate over the range tested.
[1]
Suggest one reason why the trend should not be extrapolated far beyond the range tested.
[1]
Question 32
Human muscle cells were incubated with glucose under aerobic and anaerobic conditions. ATP production and waste products were measured.
| Condition | O₂ availability | ATP yield / relative units | Lactate / mmol L⁻¹ | CO₂ produced / mmol L⁻¹ | Main cell site |
|---|---|---|---|---|---|
| Aerobic | Present | 96 | 0.2 | 14.8 | Cytoplasm and mitochondria |
| Anaerobic | Absent | 6 | 7.9 | 0.3 | Cytoplasm |
Compare the ATP yield under aerobic and anaerobic conditions.
[1]
Identify the waste product detected only under anaerobic conditions.
[1]
Explain why mitochondria are required for the aerobic condition but not the anaerobic condition.
[1]
State one limitation of using isolated cells to represent whole-muscle performance.
[1]
Question 33
A tracer experiment followed carbon compounds during glycolysis in isolated cytoplasm.
| Compound measured | Amount (molecule per glucose) |
|---|---|
| Glucose used | 1 |
| ATP used in early steps | 2 |
| ATP produced later | 4 |
| Reduced NAD formed | 2 |
| 3-carbon end product formed | 2 |
Identify the three-carbon product that accumulates at the end of glycolysis.
[1]
Use the data to determine the net ATP gain per glucose molecule.
[1]
Explain why ATP is both used and produced during glycolysis.
[1]
Question 34
During a sprint, human muscle cells may respire anaerobically.
State why anaerobic respiration may occur during a sprint.
[1]
Explain one advantage of anaerobic respiration during a sprint.
[1]
State why extra oxygen is required after the sprint.
[1]
Question 35
Name the four-carbon compound regenerated in the Krebs cycle.
[1]
Outline events in one turn of the Krebs cycle after acetyl-CoA enters.
[1]
Question 36
Explain how electron flow along the electron transport chain generates a proton gradient in mitochondria.
State the membrane in which the electron transport chain is located.
[1]
Explain how the gradient is generated.
[1]
Question 37
State the role of oxygen in aerobic respiration.
[1]
Explain why the absence of oxygen lowers ATP production.
[1]
Question 38
A student investigated the effect of glucose concentration on respiration rate in yeast by collecting gas in a syringe.
Identify the dependent variable in the investigation.
[1]
Describe the relationship between glucose concentration and respiration rate shown in the graph.
[1]
Suggest one controlled variable needed for a valid investigation.
[1]
Evaluate whether the data support the conclusion that glucose concentration is the only factor limiting respiration rate.
[1]
Question 39
Human muscle-cell extracts were incubated without oxygen. The concentrations of pyruvate, lactate, reduced NAD and NAD were monitored.
Identify the product that increases as pyruvate decreases.
[1]
Describe the change in reduced NAD shown in the graph.
[1]
Explain how the conversion of pyruvate to lactate affects NAD availability.
[1]
Suggest what would happen to ATP production if pyruvate could not be converted to lactate.
[1]
Question 40
Isolated mitochondria were supplied with pyruvate and oxygen. Products of the link reaction were measured.
| Substance | 0 min / µmol dm⁻³ | 10 min / µmol dm⁻³ |
|---|---|---|
| Pyruvate | 800 | 210 |
| Carbon dioxide | 35 | 625 |
| Reduced NAD | 20 | 610 |
| Acetyl-CoA | 15 | 600 |
Identify the gas produced during the link reaction.
[1]
Deduce from the data whether pyruvate was oxidized.
[1]
Explain the role of coenzyme A in the link reaction.
[1]
Question 41
State the word equations for aerobic and anaerobic respiration in humans using glucose as the substrate.
[1]
Compare aerobic and anaerobic respiration in humans.
[1]
Question 42
Describe the structure of ATP.
[1]
Discuss why ATP is suitable as the molecule that distributes energy within cells.
[1]
Question 43
Outline two life processes in cells that require ATP.
[1]
Explain energy transfers during interconversions between ATP and ADP.
[1]
Question 44
Mitochondria were supplied with reduced NAD. Proton concentration was measured in the matrix and intermembrane space before and after adding an electron transport inhibitor.
| Time / min | Condition | Matrix [H+] / nM | Intermembrane [H+] / nM |
|---|---|---|---|
| 0 | Before inhibitor | 22 | 78 |
| 1 | Before inhibitor | 21 | 80 |
| 2 | Before inhibitor | 22 | 79 |
| 3 | Inhibitor added | 22 | 79 |
| 4 | After inhibitor | 30 | 70 |
| 5 | After inhibitor | 37 | 62 |
| 6 | After inhibitor | 43 | 55 |
| 8 | After inhibitor | 48 | 51 |
Identify the compartment with the higher proton concentration before the inhibitor was added.
[1]
Describe the effect of the inhibitor on the proton gradient.
[1]
Explain how electron transport normally generates the proton gradient.
[1]
Predict the effect of the inhibitor on ATP synthesis.
[1]
Question 45
A researcher compared oxygen consumption and ATP production when equal masses of carbohydrate or lipid were supplied to isolated mitochondria under aerobic conditions.
| Substrate | ATP produced / mmol g^-1 | O2 consumed / mmol g^-1 |
|---|---|---|
| Carbohydrate | 167 | 33 |
| Lipid | 414 | 90 |
Identify which substrate gave the greater ATP yield per gram.
[1]
Describe the difference in oxygen consumption between the substrates.
[1]
Explain the biochemical reason for the higher energy yield of one substrate.
[1]
Evaluate whether these data show that lipid can be used for anaerobic respiration.
[1]
Question 46
A student uses a respirometer to measure oxygen uptake by germinating seeds.
Outline how the rate of respiration can be calculated from respirometer readings.
[1]
Evaluate design features that improve validity and reliability in this investigation.
[1]
Question 47
Outline the role of NAD in cell respiration.
[1]
Explain the main events of glycolysis and how its products are used under anaerobic conditions in human cells.
[1]
Question 48
Outline anaerobic respiration in yeast.
[1]
Compare anaerobic respiration in yeast and humans, including its practical significance.
[1]
Question 49
Outline how reduced NAD links earlier stages of respiration to the electron transport chain.
[1]
Explain oxidative phosphorylation in mitochondria, including the role of oxygen.
[1]
Question 50
Outline how acetyl groups enter and are oxidized in aerobic respiration.
[1]
Discuss differences between carbohydrates and lipids as respiratory substrates.
[1]
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