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The Invisible Living World: Beyond Our Naked Eye

Four kinds, not one word

In daily talk, a "germ" is a microbe that makes us ill. That one word covers very different living things.

A nucleus is the part that controls a cell.

Four kinds of microbe. Each has its own clue.
Step 1 of 5
  1. Four kinds of microbe. Each has its own clue.
  2. Bacteria: one cell. No proper nucleus.
  3. Fungi: one cell, or many threads.
  4. Protozoa: one cell. Many move about.
  5. Virus: not a cell. It needs a host.

The rule

A cell is the basic building unit of life. To multiply is to make more of the same kind of thing. A host is the living thing a virus multiplies inside.

Bacteria and protozoa are single cells. A fungus is one cell (yeast) or many threads (mould). A virus is not a cell. It multiplies only inside a host.

Where you meet each kind
KindWhere you meet it
BacteriaCurd, soil, your gut
FungiRising dough, mould on bread
ProtozoaPond water (Amoeba, Paramecium)
VirusesInside a host cell

A bacterium has a nucleoid and no well-defined nucleus. A nucleoid does the job of a nucleus but has no covering.

Drag each clue to its kind.

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This track

  1. 0 Start here
  2. 1 A world below the eye
  3. 2 Four kinds, not one word
  4. 3 Microbes are everywhere
  5. 4 The ones doing work we want
  6. 5 When food spoils
  7. 6 Helps or harms?
  8. 7 Keeping microbes from growing
  9. 8 The big picture
  10. 9 Track quiz

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