How do yeast make bread light and spongy?

Explanation

**Step-by-Step Solution:**

1. **Understanding Yeast**: Yeast is a type of fungus, specifically the species known as Saccharomyces cerevisiae, which is commonly referred to as baker's yeast.

2. **Ingredients in Bread Making**: When making bread, we typically use flour, which contains sugars. These sugars are essential for the fermentation process.

3. **Mixing Yeast and Sugar**: When yeast is mixed with sugar (from the flour), it begins to ferment. This fermentation process occurs in the absence of oxygen, which is known as anaerobic respiration.

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