AHL Content Statements

• D2.1.12

  Cell proliferation for growth, cell replacement and tissue repair

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  Include proliferation for growth within plant meristems and early-stage animal embryos as examples. Include skin as an example of cell proliferation during routine cell replacement and during wound healing. Students are not required to know details of the structure of skin.
  

• D2.1.13

  Phases of the cell cycle

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  Students should understand that cell proliferation is achieved using the cell cycle. Students should understand the sequence of events including G1, S and G2 as the stages of interphase, followed by mitosis and then cytokinesis.
  

• D2.1.14

  Cell growth during interphase

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  Students should appreciate that interphase is a metabolically active period and that growth involves biosynthesis of cell components including proteins and DNA. Numbers of mitochondria and chloroplasts are increased by growth and division of these organelles.
  

• D2.1.15

  Control of the cell cycle using cyclins

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  Limit to the concentration of different cyclins increasing and decreasing during the cell cycle and a threshold level of a specific cyclin required to pass each checkpoint in the cycle. Students are not required to know details of the roles of specific cyclins.

• D2.1.16

  Consequences of mutations in genes that control the cell cycle

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  Include mutations in proto-oncogenes that convert them to oncogenes and mutations in tumour suppressor genes, resulting in uncontrolled cell division.

• D2.1.17

  Differences between tumours in rates of cell division and growth and in the capacity for metastasis and invasion of neighbouring tissue

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  Include the terms “benign”, “malignant”, “primary tumour” and “secondary tumour”, and distinguish between tumours that do and do not cause cancer.
  AOS: Students should observe populations of cells to determine the mitotic index.