IB Biology SL

Revision Notes

1.2.9 Skills: Cell Origin & Ultrastructure

Interpreting Electron Micrographs

  • When interpreting electron micrographs to deduce the function of the cell it is important to:
    1. Identify whether it is a prokaryotic or eukaryotic cell – is a nucleus present
    2. Identify which eukaryotic cell it is (plant or animal) by looking for a cell wall or vacuole
    3. Identify the organelles present in the cells and consider their function

Electron micrograph of cell 1, downloadable IB Biology revision notes

Electron micrograph of cell 1

  • The cell had a nucleus – it is a eukaryotic cell
  • This cell did not have a cell wall or central vacuole – it is an animal cell
  • The cell has a large u-shape nucleus – it can manipulate itself through small pores
  • There are a large number of lysosomes in the cell – it can digest substances found within the cell
  • There are a large number of mitochondria – it has sufficient energy for the many metabolic reactions
  • The deduction, therefore, is that this cell needs a lot of energy to break down substances that enter the cell and that it can move where it wants. This cell is a macrophage

Electron micrograph of cell 2, downloadable IB Biology revision notes

Electron micrograph of cell 2

  • The cell had a nucleus – it is a eukaryotic cell
  • This cell did not have a cell wall or central vacuole – it is an animal cell
  • There are a large number of mitochondria – it requires significant energy for many metabolic reactions
  • The cell has microvilli packed closely together (brush border) – it needs to increase the surface area and prevent any substance from crossing into the cell
  • The deduction, therefore, is that this cell needs a lot of energy to control what enters or exits this cell and that the cell requires a lot of the substance to be absorbed. This cell is a ciliated epithelium of the small intestine

Author: Catherine

Cate has over 20 years’ experience teaching Biology to IGCSE, IB and A-level students in seven different countries across Asia, Europe, North America and the Middle East. This has given her a fine appreciation of different cultures, places and teaching methods. Cate has a keen interest in producing Biology revision resources that will help students engage with the subject.
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