The CO2 produced in one round of the citric acid cycle does not originate in the acetyl carbons that entered that round. If the acetyl-CoA is labeled with 14C at its carbonyl carbon, how many rounds of the citric acid cycle are required before 14CO2 is released

It will require second round of the cycle to release

Explanation:

Reason behind the requirement of second round of the cycle to release -:

The C4 carbon of succinyl CoA is acetyl from acetyl CoA. Succinyl CoA is converted to succinate, which is then converted to fumarate, fumarate, malate, and eventually oxaloacetate. 14C will be found in oxaloacetate at either C1 or C4. During the second round of the loop, each of these carbons will be converted to carbon dioxide.