CAIE A Level Biology 9700 · The mitotic cell cycle
In the lining of the human small intestine, stem cells in the crypts divide by mitosis to produce new epithelial cells that migrate up the villi, replacing cells shed into the lumen. Occasionally, mutations occur in genes that control the cell cycle, leading to uncontrolled cell division and the formation of a tumour.
Outline the mitotic cell cycle, including the role of telomeres, and explain how loss of control over cell division can lead to tumour formation.
5 marks, so the mark scheme is looking for about 5 separate creditworthy points. Making the same point twice in different words earns it once.
Outline means: Give the main points briefly. Less detail than describe, but every key step has to be there. One short line per step, in order. The marks are for coverage, not depth.
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