Read and understand each item and choose the letter of the best answer. Write your answer on a separate sheet of paper. 1. Which is the final electron acceptor in aerobic respiration? A. Pyruvate B. carbon dioxide 2. In the presence of oxygen, all cells synthesize ATP via the process of glycolysis. Many cells also can metabolize pyruvate if oxygen is not present, via the process of A. Fermentation C. aerobic respiration D. electron transport B. Oxidative phosphorylation 3. A cell culture was supplied with radioactively labeled Oâ‚‚. The cells were monitored. In a few minutes the radioactive oxygen atoms were present in which of the following compounds: Carbon dioxide Water 4. Majority of the COâ‚‚ is released during A. Glycolysis B. Electron transport chain 5. Suppose that a new species of organism has been discovered. Scientists have observed its cells under a microscope and determined that they lack mitochondria. What type of cellular respiration would you predict that the new species uses? Aerobic C. Both aerobic and anaerobic Anaerobic D. Cannot be determined
The Correct Answer and Explanation is :
Let’s analyze each question and determine the correct answer with explanations:
1. Which is the final electron acceptor in aerobic respiration?
Options: A. Pyruvate B. Carbon dioxide C. Oxygen D. Water
Correct Answer: C. Oxygen
Explanation: aerobic respiration, oxygen serves as the final electron acceptor in the electron transport chain. trons are transferred through a series of protein complexes, ultimately reducing oxygen to form water. Throcess is essential for the efficient production of ATP. (pmncbi.nlm.nih.gov)
2. In the presence of oxygen, all cells synthesize ATP via the process of glycolysis. Many cells also can metabolize pyruvate if oxygen is not present, via the process of:
Options: A. Fermentation B. Oxidative phosphorylation C. Aerobic respiration D. Elecon transport
Correct Answer: A. Fermentation
Explanation: When oxygen is scarce or absent, cells metabolize pyruvate through fermentatio regenerate NAD⁺, allowing glycolysis to continue producing ATP. In lactic acid fermentation, pyruvate is reduced to lactate, while in alcolic fermentation, is converted to ethanol and carbon dioxide. (bio.libretexts.org)
3. A cell culture was supplied wi radioactively labeled O₂. The cells were monitored. In a few minutes, the radioactive oxygen atoms were present in which of thllowing compounds:
Options: A. Carbon dioxide B. Water
Correct Answer: B. Water
Explanaon: In aerobic reiration, oxygen acts as the final electron acceptor in the electron transport chain and is reduced to form water. Therefore, radioactively labeled oxygen would be found in water molecules produced during this proce. (pmc.ncbi.nlm.nih.gov)
4. Majoritythe CO₂ is released during:
Options: A. Glycolysis B. Electron transport chain C. Citrcid cycle D. Oxidative phosphorylation
Correct Answer: C. Citric acid cycle
Explanation: The citric acid cyc (Krebs cycle) is thpmary stage of cellular respiration where carbon dioxide is produced. During this cycle, acetyl-CoA is oxidized, resug in the release of CO₂ as a waste product. Glycolysis produces no CO₂, and the electron transport chain and oxidative phosphorylation do not directly release CO₂. (ekipedia.org)
Understanding these processis crucial for comprehending how cells generate energy and manage metabolic byproducts. Aerobic respiration efficiently produces ATP by utilizing oxygen, while fermentation allows ATP production to continue in anaerobic conditions, albeit less efficiently. The citric acid cycle’s role in releasing CO₂ highlights its importance in cellular respiration and energy metabolism.