Microorganisms and Fermentation IGCSE Biology: Complete Guide

🦠 Understanding Microorganisms in IGCSE Biology

Microorganisms are tiny living things with many applications. This guide covers bacteria, fungi, and fermentation processes.

🧠 Memory Tips

Microorganisms: “Bacteria Viruses Fungi Protozoa”

• Bacteria: Single-celled prokaryotes
• Viruses: Need host cells
• Fungi: Include yeasts and molds
• Protozoa: Single-celled eukaryotes

Fermentation: “Yeast Sugar Alcohol Carbon-dioxide”

• Yeast: Microorganism
• Sugar: Substrate
• Alcohol: Product
• CO₂: By-product

📚 Key Concepts

Types of Microorganisms

• Bacteria: Prokaryotic, various shapes
• Fungi: Eukaryotic, include yeasts
• Viruses: Non-living, need hosts
• Protozoa: Single-celled animals

Fermentation

• Definition: Anaerobic respiration by microorganisms
• Alcoholic: Yeast produces ethanol
• Lactic acid: Bacteria produce lactate
• Applications: Food, drinks, industrial

Yeast Fermentation

• Equation: C₆H₁₂O₆ → 2C₂H₅OH + 2CO₂
• Conditions: Warm temperature, no oxygen
• Uses: Bread, beer, wine
• By-products: CO₂ makes bread rise

Bacterial Fermentation

• Lactic acid: Preserves food
• Examples: Yogurt, cheese, sauerkraut
• Anaerobic conditions: No oxygen needed
• Preservation: Acid prevents decay

🎯 Exam Focus

Common Questions:

1. Describe fermentation process (5 marks)
2. Compare different microorganisms (4 marks)
3. Explain fermentation applications (4 marks)
4. Analyze fermentation conditions (3 marks)

Key Applications:

• Food production and preservation
• Antibiotic production
• Waste treatment
• Biotechnology

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