* Chemical Composition Changes: The complex carbohydrates, sugars, and fibers in a banana are broken down into simpler molecules like glucose by enzymes in your digestive system. This alters the chemical composition of the banana.

* Irreversible: You can't simply "un-digest" a banana and get the original fruit back. The chemical reactions that occur during digestion are irreversible.

* New Substances Formed: The digestion process creates entirely new substances (like glucose) that weren't present in the original banana.

Reversible changes involve a change in the physical state or appearance of a substance, but not its chemical composition. Examples include:

* Freezing water: Ice (solid) is still H2O, just in a different state than liquid water.

* Melting chocolate: The chocolate changes from solid to liquid, but the chemical makeup remains the same.

Since the banana's chemical makeup changes during digestion, it's considered a chemical change.