The energy molecule is not stored in large quantities in cells because its high-energy phosphate bonds are too unstable.

The energy molecule referred to in the question is Adenosine Triphosphate (ATP). ATP is not stored in large quantities in cells due to the instability of its high-energy phosphate bonds. Here's a step-by-step explanation:

1. ATP is composed of an adenine base, a ribose sugar, and three phosphate groups. The bonds between these phosphate groups are high-energy because they are unstable and easily broken.

2. When these bonds are broken, a large amount of energy is released. This energy is used to power various cellular processes.

3. Because these bonds are so unstable, ATP is not stored in large quantities in cells. Instead, it is constantly being produced and used up.

4. If cells tried to store large amounts of ATP, the high-energy phosphate bonds would break down, releasing energy that the cell couldn't use immediately. This would be a waste of resources.

5. Therefore, cells produce ATP as needed, rather than storing it in large quantities. This ensures that the energy provided by ATP is available when and where it is needed.