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Consider these objects, images for which are given below:

  1. Mitochondria
  2. Arabis voch pollen
  3. Ring stage of Plasmodium falciparum
  4. Tuberculosis bacterium
  5. Human red blood cell
  6. Human nerve cell
  7. The eye of a needle
  8. Cat hair
  9. Snowflake crystal

How many do you recognise? Can you put them in order of length? Cross-sectional area? Volume? Once in order, how many of the smaller objects would fit into the larger objects?
Discussion point: What measurement difficulties does this task raise?
You can see the images, some of which contain scale information, below


Mitochondria, mammalian lung - TEM (2)

Arabis voch pollen

Arabis voch1-1

Ring stage of Plasmodium falciparum

Plasmodium falciparum in Red Blood Cells

Tuberculosis bacterium

Mycobacterium tuberculosis 8438 lores

Human red blood cell

SEM blood cells

Human nerve cell

Myelinated neuron 

The eye of a needle

Eye of a Needle

Cat hair

ESEM BSE cat hair No1194 10kV 1000x 680Pa

Snowflake Crystal

Snow crystals

The URLS of these beautiful images are as follows:


  • Mitochondria -,_mammalian_lung_-_TEM_%282%29.jpg
  • Arabis voch Pollen -  
  • Plasmodium falciparum -
  • Bacterium (tuberculosis) -    
  • Human red blood  -
  • Nerve cell -
  • Eye of a needle -
  • Cat hair -
  • Snow crystals - png: