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What Are Microorganisms
- Many tiny living things surround us.
- They are too small to see.
- A microscope or foldscope reveals them.
- These are called microorganisms.
Example 1 — Microbes in Soil
- Garden soil is full of tiny living things.
- We cannot see them with our eyes.
- So we call them microorganisms.
Example 2 — Microbes in Pond Water
- A drop of pond water holds many moving organisms.
- They become visible only under a microscope.
- So pond water is full of microorganisms.
Important Points
- The branch that studies microbes is called microbiology.
- Most microbes are harmless; only a few cause disease.
- The foldscope, a paper microscope, helps us see them.
Definition — Microorganism
A living thing too small to be seen without a microscope.
💡 Did You Know — The Foldscope
A Paper Microscope
The foldscope is a paper microscope that uses low-cost material with a fine lens. It was invented by Manu Prakash and Jim Cybulski. These cheap, good-quality microscopes are used to look at microbes, insects and tissues.
Where Microorganisms Live
- Microbes are found everywhere.
- They live in air, soil and water.
- They survive hot springs and icy water.
- They live inside us too.
Example 1 — Living in Harsh Places
- Some microbes live in hot springs.
- Others live in salty or marshy water.
- So microbes survive in almost every habitat.
Example 2 — Living as Parasites
- Some microbes live on other living things.
- They live inside humans and animals too.
- So microbes can live as parasites.
Important Points
- Microbes that live on other living things are parasites.
- Helpful gut bacteria live inside our own intestines.
- Their wide range shows how well microbes adapt.
Definition — Parasite
A living thing that lives on or inside another living thing.
Materials needed
Moist soil, a beaker, water, a dropper, a glass slide, a cover slip, pond water and a microscope or foldscope.
Procedure
Collect moist soil in a beaker and add water to it.
Let the soil settle, then take a drop from the top layer onto a slide.
Cover with a cover slip so no air bubble enters and view under a microscope.
Next, take a few drops of pond water, spread on a clean slide and cover it.
View this slide under a microscope too.
Let the soil settle, then take a drop from the top layer onto a slide.
Cover with a cover slip so no air bubble enters and view under a microscope.
Next, take a few drops of pond water, spread on a clean slide and cover it.
View this slide under a microscope too.
Observation
In both slides we see tiny organisms moving around.
Explanation
The moving organisms are too small to see with the eye but show up under a microscope. This proves that both soil and pond water contain microorganisms.
◆ Summary
- Mix soil with water
- Let it settle
- Take top drop
- View under microscope
- Tiny organisms move
Subjective Type Questions - Short Answer Q7 - Page 35 Lakhmir Singh
Question
What are microorganisms? Give any two examples of microorganisms.
Show answer
Microorganisms are living things too small to be seen without a microscope. Examples: bacteria and Amoeba.
Explanation
- Micro means extremely small.
- We need a microscope to see them.
- Bacteria, Amoeba, yeast and algae are microorganisms.
