Which of these parts of the human body are made of cells?

Imagine that a new disease appears which destroys anything made of cells. Which of the following will be destroyed by this disease? 

• humans        
• air
• fire                                 
• bacteria
• meat
• trees
• clouds
• plastic 
• crops 
• rivers 
• dead bodies

How did you decide what would be destroyed by the disease?

For the above given question, did you guess or did you use evidence to get your answer? Which is the best approach?

How can you tell if your evidence is reliable or not?

Using electron microscopes to research cells

The below photograph was taken using an electron microscope and shows a small part of a plant cell.

Electron microscopes are used to produce magnified images of cell components. The magnification of an image is how much larger it is than the actual structures. Work out the magnification of this photo by following these steps:

a) Use a ruler to measure the diameter of the nucleus in the photo. Do this in millimeters, not centimeters. 

b) Convert the diameter in millimeters to micrometers.

c) Divide the diameter of the nucleus in the photo by its actual diameter, $3.3 \mathrm{\mu m}$. Be sure that both diameters are in micrometers. The value that you have calculated is the magnification of the photo.