Pearson Edexcel IAL Biology 3.16 Mitotic index calculations
Practise calculating mitotic index from counted cells, percentages, microscope images and cell-cycle data tables.
- Syllabus
- First assessment 2019
- Course
- Biology YBI11
- Level
- AS
Exam points
- apply mitotic index as cells in mitosis divided by total cells, with percentage conversion when needed
- calculate missing cell numbers from mitotic index, totals, graph readings or stage percentages
- determine proportions of cells in nuclear division from tables, photographs or cancer cell data
3.16—Mitotic index calculations question 1
Flowering plants produce seeds that can be stored in a seed bank. This is done to conserve the biodiversity of plants.
Question (a)
(a)
The longer seeds are stored in seed banks, the less likely they are to germinate. This is due to ageing.
Ageing of seeds can affect the growth of roots when the seeds germinate.
Determining the mitotic index of roots is one way to study growth of roots.
[ 7 ]
Question (i)
(i)
Describe how the mitotic index of roots can be determined.
[ 4 ]
Question (ii)
(ii)
Seeds can be treated to artificially age them.
In an investigation, untreated and treated samples of seeds were germinated and the roots allowed to grow.
Roots of different lengths from the untreated seeds, seeds treated for 4 days and seeds treated for 14 days were selected.
The mitotic index of these roots was determined.
The graph shows the results of this investigation.
There were 14 cells undergoing mitosis in 8 mm roots from seeds treated for 4 days. Calculate the total number of cells that were counted when the mitotic index was determined.
(3)
Total cells counted
[ 3 ]
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