Final answer:
An increase in cellular acetyl-CoA is likely to up-regulate enzyme activity.
Step-by-step explanation:
When there is an increase in cellular acetyl-CoA, it is likely to up-regulate enzyme activity. Acetyl-CoA is a key molecule involved in various metabolic pathways, including the Krebs cycle and fatty acid synthesis. It serves as a substrate for many enzymes, such as acetyl-CoA carboxylase, which is involved in fatty acid synthesis. When there is an increase in cellular acetyl-CoA, it can stimulate the activity of these enzymes, leading to an up-regulation of enzyme activity.