Which of the following statements about anaerobic respiration is FALSE?
A) It involves the reduction of an organic final electron acceptor.B) The complete Kreb’s cycle is utilized.C) It yields lower amounts of ATP when compared to aerobic respiration.D) It generates ATP.E) It requires cytochromes.
The correct answer and explanation is:
The correct answer is B) The complete Krebs cycle is utilized.
Explanation:
Anaerobic respiration refers to the process by which cells generate energy (ATP) without the use of oxygen. It occurs when oxygen is not available, and an alternative electron acceptor, usually an inorganic molecule like nitrate or sulfate, is used instead. Here’s a breakdown of the statements:
- A) It involves the reduction of an organic final electron acceptor: This statement is true. In anaerobic respiration, the final electron acceptor is typically an organic molecule like pyruvate or a derivative of it, such as acetaldehyde in fermentation processes. This is in contrast to aerobic respiration, where oxygen is the final electron acceptor.
- B) The complete Krebs cycle is utilized: This statement is false. In anaerobic respiration, the full Krebs cycle does not occur as it does in aerobic respiration. While glycolysis and some of the preparatory steps for the Krebs cycle can take place, the full cycle is bypassed because oxygen is absent, preventing the operation of the electron transport chain, which is critical for completing the Krebs cycle. Instead, alternative metabolic pathways are used to regenerate electron carriers like NAD+.
- C) It yields lower amounts of ATP when compared to aerobic respiration: This statement is true. Anaerobic respiration produces far less ATP than aerobic respiration because the electron transport chain, which is responsible for the bulk of ATP generation, cannot function without oxygen. Anaerobic respiration typically generates only 2 ATP molecules per glucose molecule, compared to up to 38 ATP in aerobic respiration.
- D) It generates ATP: This statement is true. Despite the lower yield of ATP, anaerobic respiration still generates ATP. The energy is primarily derived from glycolysis, which breaks down glucose into pyruvate, and some energy is conserved in the form of ATP.
- E) It requires cytochromes: This statement is true. In certain types of anaerobic respiration, like nitrate or sulfate reduction, cytochromes are involved as part of the electron transport system to transfer electrons. However, the exact nature of the electron transport chain varies depending on the organism and the electron acceptor used.
In summary, the key difference between anaerobic and aerobic respiration is the absence of the full Krebs cycle and oxygen as the final electron acceptor in anaerobic respiration.