The bread becomes soft and porous when the yeast cells are mixed in the lump of dough of wheat flour, because

Options

A. Yease is soft and flour also become soft
B. Yeast produces acetic acid and alcohot which gives softness to the bread
C. Evolution of `CO_(2)` makes the bread spongy
D. Yeast produces benzoic acid.

Answer

To answer the question, "The bread becomes soft and porous when the yeast cells are mixed in the lump of dough of wheat flour, because," we need to understand the role of yeast in the bread-making process.

### Step-by-Step Solution:

1. **Understanding Yeast**: Yeast, specifically the species Saccharomyces cerevisiae, is a type of fungus that is commonly used in baking. It is a unicellular organism that ferments sugars.

2. **Mixing Yeast with Dough**: When yeast is added to the dough made from wheat flour, it begins to metabolize the sugars present in the flour.

3. **Fermentation Process**: The fermentation process is the key reaction that occurs. During fermentation, yeast converts sugars (like glucose) into ethanol (alcohol) and carbon dioxide gas through a process called anaerobic respiration.

4. **Production of Carbon Dioxide**: The carbon dioxide gas produced during fermentation gets trapped in the dough. As the gas expands, it creates bubbles, which causes the dough to rise and become soft and porous.

5. **Final Result**: The release of carbon dioxide is what makes the bread spongy and gives it a light texture. The alcohol produced evaporates during baking, leaving behind the soft and airy structure of the bread.

6. **Conclusion**: Therefore, the correct reason why bread becomes soft and porous is due to the evolution of carbon dioxide during the fermentation process.

### Final Answer:
The bread becomes soft and porous when the yeast cells are mixed in the lump of dough of wheat flour because the evolution of carbon dioxide makes the bread spongy.

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