State the beneficial effects ( or usefulness ) of micro - organisms in our lives.

Explanation

**Step-by-Step Solution:**

1. **Introduction to Micro-organisms**: Micro-organisms are tiny living organisms that can only be seen under a microscope. They include bacteria, fungi, viruses, and protozoa.

2. **Fermentation**: One of the significant beneficial effects of micro-organisms is their role in fermentation. Yeast, a type of fungus, is used in the production of bread and beer. During fermentation, yeast converts sugars into alcohol and carbon dioxide, which helps in leavening bread and brewing beer.

3. **Vaccination**: Certain bacteria are crucial in the development of vaccines. For example, the antibiotic streptomycin, which is produced by bacteria, is used to treat tuberculosis. This shows how micro-organisms can help in disease prevention and treatment.

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