Life Too Small to See! 🔎
**Microorganisms**, or microbes, are tiny living things that can only be seen using a microscope. They are everywhere—in the air, in the soil, in water, and even inside your body! The four main types we study are **Bacteria**, **Fungi**, **Protozoa**, and **Viruses** (though viruses aren't technically "living").
Most microbes are harmless, and many are actually **beneficial**! They help us digest food, clean up pollution, and make yogurt and cheese.
The Four Main Microbes 🔬
They all look and act differently:
1. Bacteria 🟢 (Single-celled)
Simple, one-celled organisms. They can be good (like those in your gut) or bad (causing illnesses like strep throat). They reproduce very quickly!
2. Fungi 🍄 (Yeast, Molds)
Organisms like yeast (used to bake bread) and mold (found on old food). Some cause minor infections like athlete's foot.
3. Viruses 🔴 (Non-living)
The smallest of all. Viruses are NOT cells—they are genetic material wrapped in a protein coat. They must invade a host cell to reproduce. They cause the flu and colds.
Video: The Germ Theory of Disease 🎬
Watch how scientists discovered that tiny microbes cause sickness.
Practice Problems (What is it?)
Read the description and click the correct microorganism.
⚡ Good or Bad Microbe?
Click on the examples that show a **Beneficial (Good)** use for microorganisms!
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