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B1 (Electron Microscope, Enzymes, Cells, The Light Microscope, DNA,…

- - - - Order of magnitude is the sizes of the cells. It is calculated in factors of 10s
  - - - Prokaryotic cells are smaller than eukaryotic cells. around 1 micro-meter across. Their DNA is not enclosed in a nucleus. It is found as a single molecule in a loop. They may have one or more small rings of DNA called plasmids.
      - Bacteria and Archaea
- - - - Using higher magnification does not result in seeing an image in better detail. This depends on the resolving power.
        
        The resolving power is the ability to distinguish between two points. The resolving power of a light microscope is around 0.2 micrometers.
- - - - adenine (A)
      - thymine(T)
      - cytosine (C)
      - guanine(G)
    - - Complementary bases: A-T; C-G
- - - - Live cells mounted by saline solution on a microscope slide
      - Most cells are colourless, so iodine solution or methylene blue is used to stain plant cells. We must stain them to add colour and contrast.
    - - The slide is first viewed in low power, this is because the field of view with high power is small. It would be difficult to locate cells if starting with the high power objective
      - A low power objective enables you to see the layout of cells within the tissue
      - Low power objective is also useful when estimating the numbers of different types of cell on the slide or in a tissue- high power may be needed
      - Low power digital image can be used to show arrangement of cells in a tissue. The regions of the tissue, but not individual cells.. Cells or tissue can be viewed with high power to produce a detailed image of a part of the slide.
    - - A microscope drawing or micrograph is little of indication of size. A scale bar is used. Though any scale bar must be drawn for an appropriate dimension and a sensible size in relation to the image.