Biology 9700 · AS & A Level · Replication and division of nuclei and cells

Replication and division of nuclei and cells — practice question

Mitotic index is a way of measuring the proportion of cells in a section of tissue that are undergoing mitosis. It is found by using the formula shown: mitotic index = (number of cells undergoing mitosis \div total number of cells) \times 100. A scientist worked out the mitotic index for regions of onion root at different distances from the root tip. The results are shown. Which statement is correct?

  • ANo cell division occurs further than 1.4 mm from the tip of the root.
  • BThe rate of cell division decreases as the distance from the root tip decreases.
  • CMost of the cells undergoing cell division are closer to the tip of the root.
  • DFor a sample of 200 cells 0.2 mm from the tip of the root, 6 would be undergoing mitosis.

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