Final answer:
The mitochondria would be the organelle most likely affected first if there was no glucose present to convert energy for cellular needs.
Step-by-step explanation:
If there is no glucose present to convert energy for cellular needs, the organelle that would most likely be affected first is the mitochondria. Mitochondria are responsible for the production of ATP, which is the cell's main energy-carrying molecule. Without glucose, the mitochondria would not be able to carry out cellular respiration and generate ATP.