Muscle Energy Loop

In the picture

1. 1Muscle fibre: the working cell structure that contracts and spends energy
2. 2Glucose unit: a fuel piece carried into the cell
3. 3Split ATP molecule: releases immediate energy
4. 4Rebuilt ATP molecule: stores energy again for later use
5. 5ATP reserve: a tiny store that lasts seconds

Examples

• Running for a bus: leg muscles burn ATP within seconds and rebuild it as you breathe faster.
• Lifting a backpack: arm muscles use ATP immediately, then refill it from glucose in your cells.

Quiz: Muscle Energy Loop (Age 15)

1. 1

   According to the card, what is ATP used as in cells?

   • A long-term energy store
   • The cell’s immediate energy currency
   • A fuel piece carried into the cell
2. 2

   Why do cells constantly rebuild ATP from glucose?

   • Because glucose is the cell’s immediate energy currency
   • Because stored ATP lasts only moments
   • Because ATP must be converted to glucose before use
3. 3

   What happens when an ATP molecule is split?

   • It stores energy again for later use
   • It carries glucose into the cell
   • It releases immediate energy

The answers, each with its explanation, are in the app. This lesson has left the free week, so its quiz is part of the subscription.