Yeasts are used in the production of

Options

A. (a) idli
B. (b) beer
C. (c) bread
D. (d) all of these

Answer

### Step-by-Step Solution:

1. **Identify the Organism**: The question asks about yeasts, specifically the scientific name of a commonly used yeast, which is *Saccharomyces cerevisiae*.

2. **Understand Yeast Function**: Yeasts are single-celled fungi that can perform anaerobic fermentation. This means they can convert sugars into energy without the presence of oxygen.

3. **Fermentation Process**: In the fermentation process, yeast takes glucose (a type of sugar) and converts it into pyruvate. This pyruvate is then further converted into two main products: ethanol (alcohol) and carbon dioxide.

4. **Products of Fermentation**: The two products of anaerobic fermentation are:
- **Ethanol**: This is the alcohol produced during fermentation.
- **Carbon Dioxide**: This gas is responsible for the bubbles in products like bread and beer.

5. **Applications of Yeast**: Yeast is widely used in various food and beverage industries:
- **Baking**: Yeast is used in making bread and idli, where the carbon dioxide produced helps the dough rise, creating a light and airy texture.
- **Brewing**: Yeast is also used in the production of alcoholic beverages like beer and wine.
- **Fermentation**: The sour taste in fermented products is due to the presence of ethanol and the by-products of fermentation.

6. **Conclusion**: Given the various applications of yeast in food production, the correct answer to the question is that yeasts are used in the production of idli, beer, and bread. Therefore, the answer is "all of these."

### Final Answer:
Yeasts are used in the production of idli, beer, and bread. The correct option is D: all of these.

---