- Which of the following processes occurs in the mitochondria?
a) Glycolysis
b) Fermentation
c) Krebs cycle
d) Photosynthesis
Answer: c) Krebs cycle
Explanation: The Krebs cycle takes place in the mitochondria, where it plays a key role in aerobic respiration.
- What does the term “aerobic” mean?
a) In the presence of oxygen
b) In the absence of oxygen
c) Requires carbon dioxide
d) Requires sunlight
Answer: a) In the presence of oxygen
Explanation: “Aerobic” refers to processes that require oxygen, such as aerobic respiration.
- What is the ultimate purpose of cellular respiration in plants?
a) To produce glucose
b) To produce oxygen
c) To generate energy in the form of ATP
d) To produce water
Answer: c) To generate energy in the form of ATP
Explanation: The main purpose of cellular respiration is to generate ATP, which is used for various cellular activities.
- Which of the following is a product of the electron transport chain in cellular respiration?
a) Carbon dioxide
b) Oxygen
c) ATP
d) Pyruvate
Answer: c) ATP
Explanation: The electron transport chain generates ATP by transferring electrons and creating a proton gradient, which drives ATP synthesis.
- How many molecules of NADH are produced during one round of the Krebs cycle?
a) 1
b) 2
c) 3
d) 4
Answer: c) 3
Explanation: For each cycle of the Krebs cycle, three NADH molecules are produced per acetyl-CoA molecule.
- Which of the following is true about fermentation?
a) It requires oxygen
b) It produces a large amount of ATP
c) It occurs in the absence of oxygen
d) It occurs only in animal cells
Answer: c) It occurs in the absence of oxygen
Explanation: Fermentation is an anaerobic process that occurs when oxygen is not available, producing ATP through substrate-level phosphorylation.
- During which phase of cellular respiration is glucose split into two molecules of pyruvate?
a) Krebs cycle
b) Electron transport chain
c) Glycolysis
d) Calvin cycle
Answer: c) Glycolysis
Explanation: In glycolysis, glucose is broken down into two molecules of pyruvate, producing a small amount of ATP in the process.
- Which of the following are the end products of alcoholic fermentation?
a) Ethanol and carbon dioxide
b) Lactic acid and oxygen
c) Glucose and ATP
d) Oxygen and glucose
Answer: a) Ethanol and carbon dioxide
Explanation: Alcoholic fermentation produces ethanol and carbon dioxide as byproducts, typically in yeast cells and some plant cells.
- What is the significance of NAD+ in cellular respiration?
a) It donates electrons during the electron transport chain
b) It is involved in producing glucose
c) It is an electron carrier that helps oxidize glucose
d) It produces oxygen
Answer: c) It is an electron carrier that helps oxidize glucose
Explanation: NAD+ accepts electrons during glycolysis and the Krebs cycle, becoming NADH, which is used in the electron transport chain.
- Which of the following is the main purpose of the citric acid cycle (Krebs cycle)?
a) To produce glucose
b) To produce oxygen
c) To generate electron carriers (NADH and FADH2)
d) To break down glucose
Answer: c) To generate electron carriers (NADH and FADH₂)
Explanation: The Krebs cycle generates NADH and FADH₂, which are used in the electron transport chain to produce ATP.
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