Here's why:

* Yeast is a living organism: Yeast cells are made of complex organic molecules. They need sugars and oxygen to survive and produce carbon dioxide and alcohol (in the process of fermentation).

* Peroxide is a strong oxidizer: Hydrogen peroxide (H₂O₂) is a powerful oxidizer. It readily breaks down into water and oxygen, releasing free radicals that can be harmful to living cells.

What happens when yeast and peroxide are mixed?

The peroxide will likely kill the yeast cells. The strong oxidizing nature of peroxide disrupts the cell membranes and damages internal components, leading to cell death.

It's important to note: This reaction isn't a typical chemical reaction like you might see in a test tube. It's a biological process where the peroxide acts as a toxic agent on the yeast cells.

If you are looking for a specific chemical reaction, you may be thinking about:

* Yeast and sugar: This is a classic fermentation reaction where yeast converts sugar into alcohol and carbon dioxide.

* Peroxide and other substances: Peroxide reacts with various compounds, like catalase (an enzyme found in many organisms) to break down into water and oxygen.

Let me know if you have any other questions about yeast or peroxide.