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BIOLOGY, M1 2017 HSC 10 MC

A scaled outline of a cell is shown.
 

What is the diameter of the cell?

  1. \( 7\mu \text{m}\)
  2. \( 10\mu \text{m}\)
  3. \( 12\mu \text{m}\)
  4. \( 15\mu \text{m}\)
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\(B\)

Show Worked Solution
  • The diameter of the cell is 2 times the length of the 5μm scale reference.

\(\Rightarrow B\)

BIOLOGY, M1 2008 HSC 18

Using a light microscope, a student looked at a prepared slide of human blood, and drew a scaled diagram.

The diagram shown is a representation of the student's scaled diagram.
 

  1. Assess the accuracy of the diagram.  (3 marks)

  2. Why is it safer to use prepared slides instead of fresh blood?  (1 mark)

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a.    The diagram has the following inaccuracies:

  • The scale is wrong as red and white blood cells are much smaller. A more accurate scale would use micrometres as apposed to millimetres.
  • Relative size of red and white blood cells is wrong, as WBC’s are on average 1.5 – 2 times bigger than RBC’s. 

b.   A slide with fresh blood could contain pathogenic bacteria, leading to disease.

Show Worked Solution

a.    The diagram has the following inaccuracies:

  • The scale is wrong as red and white blood cells are much smaller. A more accurate scale would use micrometres as apposed to millimetres.
  • Relative size of red and white blood cells is wrong, as WBC’s are on average 1.5 – 2 times bigger than RBC’s. 

b.   A slide with fresh blood could contain pathogenic bacteria, leading to disease.