ThinkRankMicroorganisms: Friend and Foe
Microorganisms are tiny organisms found in soil, water, air, food, and living bodies. They support fermentation, decomposition, medicines, and nutrient cycles, but some cause disease or spoil food. Useful applications depend on controlling conditions and separating beneficial activity from harmful contamination.
Learning Objectives
- •Explain microbial diversity
- •Explain useful processes
- •Explain control prevents harm
Key Concepts
Microbial diversity
Bacteria, fungi, protozoa, algae, and some viruses differ in structure, habitat, and effects; not all microorganisms are harmful.
Useful processes
Yeast fermentation, decomposition, nitrogen fixation, and antibiotic production show how microbes support food, soil, and medicine.
Control prevents harm
Hygiene, pasteurisation, refrigeration, vaccination, and safe food storage reduce disease and spoilage.
Terminology
Historical Insight
Curd and bread
Lactic acid bacteria help set curd, while yeast produces carbon dioxide that makes dough rise.
Nitrogen cycle
Some bacteria convert atmospheric nitrogen into forms plants can use, supporting soil fertility.
Quick Check
Why are antibiotics not useful against every illness?
How does pasteurisation improve safety?
Give one helpful and one harmful role of microorganisms.
How to use this lesson
Read the overview first, then explain the main idea in your own words before checking the key concepts. Use the quick-check questions without looking at the answer. For examination preparation, verify dates, definitions, and syllabus requirements against your official textbook and school or examination-board guidance.