OCR A Level Biology:复习笔记2.1.3 Drawing Cells

Drawing Cells

  • To record the observations seen under the microscope (or from photomicrographs taken) a labelled biological drawing is often made
  • Biological drawings are line pictures which show specific features that have been observed when the specimen was viewed
  • There are a number of rules/conventions that are followed when making a biological drawing

Guidelines for microscope drawings

  • The conventions are:
    • The drawing must have a title
    • The magnification under which the observations shown by the drawing are made must be recorded
    • A sharp HB pencil should be used (and a good eraser!)
    • Drawings should be on plain white paper
    • Lines should be clear, single lines (no thick shading)
    • No shading
    • The drawing should take up as much of the space on the page as possible
    • Well-defined structures should be drawn
    • The drawing should be made with proper proportions
    • Label lines should not cross or have arrowheads and should connect directly to the part of the drawing being labelled
    • Label lines should be kept to one side of the drawing (in parallel to the top of the page) and drawn with a ruler

     

  • Drawings of cells are typically made when visualizing cells at a higher magnification power, whereas plan drawings are typically made of tissues viewed under lower magnifications (individual cells are never drawn in a plan diagram)

An example of a tissue plan drawn from a low-power image of a transverse section of a root. There is no cell detail present.

 

An example of a cellular drawing taken from a high-power image of phloem tissue.

 

Exam Tip

When producing a biological drawing, it is vital that you only ever draw what you see and not what you think you see.To accurately reflect the size and proportions of structures you see under the microscope, you should get used to using the eyepiece graticule.You should be able to describe and interpret photomicrographs, electron micrographs and drawings of typical animal cells.

 

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