Oxaloacetate uniformly labeled with 14c (i.e., with equal amounts of 14c in each of its carbon atoms) is condensed with unlabeled acetyl-coa. after a single pass through the citric acid cycle back to oxaloacetate, what fraction of the original radioactivity will be found in the oxaloacetate?

answer is 1/2. explain how and why that is correct.

Your answer is correct as ½ fraction of 14C signal would be recovered.

The original oxaloacetate scaffold has 4 labeled carbon atom of which 2 labeled carbon atom are deposited as the other 2 labeled carbon atom are lost during the Krebs cycle resulting in ½ fraction of 14C signal to be recovered.

In the Krebs cycle, the oxaloacetate-contributed carbons gives the 2 carbon atoms involved in the releasing of two molecules of CO2

Messages to and from the brain travel along the nerves, which are strings of long, thin cells called neurons (see Figure 6.2). Chemical- electrical signals travel down the neurons much as flame travels along a firecracker fuse. ... Dendrites receive impulses, or messages, from other neurons and send them to the cell body.