Year 7 Science – Microorganisms

🦠 What are Microorganisms?

Microorganisms (also called microbes) are living things that are too small to see without a microscope.

They are found everywhere – in the air, water, soil, and even inside our bodies.

Some microorganisms are helpful, while others are harmful.

🔬 Types of Microorganisms

Bacteria

Bacteria are single-celled microorganisms. Some bacteria are helpful, such as those that help digest food or make yogurt. Other bacteria are harmful and can cause diseases like food poisoning.

Viruses

Viruses are very small and are always harmful. They cannot reproduce on their own and need a host (like a human or animal) to survive.

Fungi

Fungi include yeast, mold, and mushrooms. Yeast is used to make bread, while some fungi can cause infections.

Algae

Algae are plant-like microorganisms that usually live in water. Some algae produce oxygen and are food for aquatic animals.

🍞 Uses of Microorganisms

• Making food (bread, yogurt, cheese, alcohol)
• Producing medicines such as antibiotics
• Cleaning up oil spills (bioremediation)
• Helping digestion inside the human body

⚠️ Harms of Microorganisms

• Cause diseases in humans, animals, and plants
• Spoil food
• Cause infections and food poisoning

✅ Helpful vs ❌ Harmful Microbes

Helpful Microbes

• Make food
• Produce medicine
• Help clean the environment

Harmful Microbes

• Cause diseases
• Spoil food
• Make people and animals sick

📝 Key Words

• Microorganism – a living thing too small to see without a microscope
• Bacteria – single-celled microorganisms
• Virus – a harmful microorganism that needs a host
• Fungi – microorganisms like yeast and mold
• Algae – plant-like microorganisms found in water
• Host – a living thing that a virus lives in
• Antibiotics – medicine used to kill bacteria
• Bioremediation – using microorganisms to clean pollution