51. The Krebs cycle begins after pyruvate is converted into acetyl-CoA. Acetyl-CoA is further broken down in the cycle, and carbon dioxide is released.How is energy stored during the Krebs cycle?
Answer: C
Energy is stored during the Krebs cycle by adding phosphate to ADP, forming ATP.
During the Krebs cycle, energy is captured in the form of ATP by the phosphorylation of ADP, resulting in the formation of ATP from ADP and inorganic phosphate.
A) Phosphate is removed from ATP, forming ADP.
This option describes the process of dephosphorylation, which releases energy rather than storing it. During the Krebs cycle, energy is not stored by removing phosphate but rather by adding it to ADP.
B) Phosphate is removed from ADP, forming ATP.
This statement is incorrect as it misrepresents the phosphorylation process. ATP is synthesized from ADP by adding a phosphate group; therefore, phosphate is not removed from ADP to form ATP.
C) Phosphate is added to ADP, forming ATP.
This is the correct explanation of how energy is stored during the Krebs cycle. The process of substrate-level phosphorylation involves the addition of a phosphate group to ADP, which converts it into ATP, thereby storing energy.
D) Phosphate is added to ATP, forming ADP.
This option is inaccurate because it suggests that adding a phosphate group to ATP would create ADP, which is not how energy storage occurs. Instead, ATP is produced from ADP by adding a phosphate group during the Krebs cycle.
Conclusion
The correct answer is C, as it accurately describes the process of energy storage in the Krebs cycle through the addition of phosphate to ADP to form ATP. All other options either misrepresent the biochemical processes involved or describe reactions that do not contribute to energy storage in this context.