AEROBIC AND ANAEROBIC
Where does aerobic respiration mainly take place in the cell?
A. Cytoplasm of the cell
B. Nucleus of the cell
C. Mitochondria of the cell
D. Ribosome of the cell
C
Where does glycolysis occur in the cell?
A. Cytoplasm of the cell
B. Mitochondrial matrix
C. Inner cell membrane
D. Nuclear envelope membrane
A
Glycolysis happens in the cytoplasm and breaks glucose into two molecules of pyruvate.
What molecule enters glycolysis at the beginning of the process?
A. Glucose
B. Pyruvate
C. Carbon dioxide
D. Water
A
The process begins with one molecule of glucose, a six-carbon sugar.
Which molecule combines with Acetyl-CoA at the start of the Krebs Cycle?
A. Oxaloacetate
B. Glucose
C. Pyruvate
D. NADH
What is the exact location of the Electron Transport Chain?
A. Inner membrane of the mitochondria
B. Outer membrane of the mitochondria
C. Outer membrane of the chloroplast
D. Nucleus of the eukaryotic cell
A
The ETC occurs along the inner mitochondrial membrane where protein complexes are located.
What is the main difference between aerobic and anaerobic respiration?
A. Glucose is used only in anaerobic respiration
B. Oxygen is used in aerobic but not in anaerobic
C. ATP is formed only in anaerobic respiration
D. Enzymes are required only in aerobic respiration
B
Aerobic respiration needs oxygen, while anaerobic respiration occurs without it.
What are the final products of the electron transport chain?
A. Water molecules and ATP energy
B. Carbon dioxide and ethanol gas
C. Oxygen molecules and glucose sugar
D. Pyruvate acids and lactic acid
A
The electron transport chain produces ATP and forms water when oxygen accepts the electrons at the end.
Why does glycolysis not need oxygen to occur?
A. It occurs only inside the cell’s nucleus
B. It produces oxygen as a by-product
C. It takes place in the cytoplasm
D. It needs only carbon dioxide to continue
C
Glycolysis is an anaerobic process that happens in the cytoplasm, so it does not rely on oxygen.
What is the purpose of NADH and FADH₂ produced in the Krebs Cycle?
a) To carry electrons to the electron transport chain
b) To release carbon dioxide from the cell
c) To store ATP in the cytoplasm
d) To convert oxygen into glucose
A
NADH and FADH₂ are electron carriers that transport high-energy electrons to the electron transport chain for ATP production.
Why does the Electron Transport Chain produce the most ATP?
A. It changes glucose into smaller molecules
B. It stores oxygen for later use in glycolysis
C. It uses stored electrons to make energy efficiently
D. It directly converts CO₂ into ATP energy
C
The ETC converts high-energy electrons into ATP efficiently through chemiosmosis, producing about 34 ATP.
Why do plants and animals depend on aerobic respiration for survival?
A. It decreases oxygen and increases nitrogen
B. It converts lactic acid back into carbon
C. It provides sufficient ATP for life processes
D. It removes all carbon dioxide from the body
C
Aerobic respiration efficiently produces large amounts of ATP, which organisms need to perform vital functions.
How many ATP molecules are produced from one glucose during cellular respiration?
A. About 36 to 38 ATP
B. About 10 to 12 ATP
C. About 20 to 22 ATP
D. About 6 to 8 ATP
A
One glucose molecule yields approximately 36–38 ATP through glycolysis, the Krebs cycle, and the electron transport chain.
What are the end products formed after glycolysis?
A. One glucose, one ATP, one NADH
B. Two glucose, two ATP, two FADH₂
C. Two pyruvate, two ATP, two NADH
D. Two pyruvate, four ATP, two FADH₂
C
Glycolysis produces 2 pyruvate molecules, 2 net ATP, and 2 NADH from one glucose molecule.
What gas is released during the formation of Acetyl-CoA?
A. Carbon dioxide gas
B. Oxygen gas
C. Hydrogen gas
D. Nitrogen gas
A
During Acetyl-CoA formation, pyruvate loses a carbon atom, which is released as carbon dioxide.
Why does ATP production stop when oxygen is unavailable?
A. The ETC cannot pass electrons without oxygen
B. The mitochondria produce too much carbon dioxide
C. The Krebs Cycle continues but forms no water
D. The cytoplasm releases extra ATP through glycolysis
A
Oxygen serves as the final electron acceptor; without it, the chain halts and ATP formation drops drastically.
What is the main purpose of cellular respiration?
A. To absorb sunlight for making glucose
B. To release oxygen from carbon dioxide
C. To store fats inside the mitochondria
D. To produce energy in the form of ATP
D
Cellular respiration’s main goal is to produce ATP by breaking down glucose molecules.
Why is oxygen needed in cellular respiration?
A. It directly converts glucose into pyruvate molecules
B. It breaks down lactic acid formed during exercise
C. It provides carbon for the Krebs cycle reaction
D. It serves as the final electron acceptor in the ETC
D
Oxygen accepts electrons at the end of the electron transport chain, allowing ATP production to continue.
What is the role of NAD⁺ during glycolysis?
A. It provides carbon for glucose production
B. It captures electrons to form NADH for later energy use
C. It acts as an enzyme to split ATP molecules
D. It transfers oxygen to the mitochondria
B
NAD⁺ accepts electrons during glycolysis and becomes NADH, which carries energy to the next stages.
What is the role of the Krebs cycle in cellular respiration?
A. It generates electron carriers NADH and FADH₂
B. It converts oxygen into usable energy
C. It stores glucose for later ATP production
D. It breaks water molecules into hydrogen gas
A
The Krebs cycle produces NADH and FADH₂ that carry high-energy electrons to the electron transport chain.
What is the final electron acceptor in the Electron Transport Chain?
A. Glucose sugar
B. Carbon dioxide
C. Pyruvate acid
D. Oxygen
D
Oxygen accepts the electrons at the end of the chain, forming water as the final product.
What would happen if oxygen were suddenly unavailable in a human body?
A. Cells would increase the electron transport rate
B. Mitochondria would release more ATP energy
C. Cells would shift to anaerobic respiration
D. The Krebs cycle would continue producing water
C
Without oxygen, cells switch to anaerobic respiration to make limited ATP, but this leads to lactic acid buildup.
What is the role of the Krebs cycle in cellular respiration?
A. It generates electron carriers NADH and FADH₂
B. It converts oxygen into usable energy
C. It stores glucose for later ATP production
D. It breaks water molecules into hydrogen gas
A
The Krebs cycle produces NADH and FADH₂ that carry high-energy electrons to the electron transport chain.
Why is glycolysis considered the first step in cellular respiration?
A. It provides pyruvate and energy carriers needed for later stages
B. It releases carbon dioxide used in the Krebs Cycle
C. It directly forms large amounts of ATP from sunlight
D. It converts oxygen into glucose for mitochondria
A
Glycolysis begins the process of energy extraction by creating pyruvate and NADH for later use in respiration.
What is the main function of Acetyl-CoA in cellular respiration?
a) It transports electrons to the thylakoid membrane
b) It stores oxygen used during glycolysis
c) It acts as a waste product for the mitochondria
d) It carries carbon into the Krebs Cycle for energy production
D
Acetyl-CoA delivers a two-carbon group to the Krebs Cycle to start the process of energy release.
What molecules bring high-energy electrons to the ETC?
a. Oxygen and carbon dioxide molecules
b. ATP and ADP molecules
c. Glucose and pyruvate molecules
d. NADH and FADH₂ molecules
D
NADH and FADH₂ carry high-energy electrons from the Krebs Cycle to the ETC.