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Edexcel IAL Biology 3P.3 Experimental design and method evaluation

Identify the specific weakness, explain how it biases or limits the data and propose a feasible change that directly improves validity, reliability or precision.

Syllabus
First assessment 2019
Course
Biology YBI11
Level
AS

Exam points

  • Extend an investigation with justified variable values, times or biological samples.
  • Choose the more valid data set through sample size and control of variables.
  • Explain how a method choice or control prevents bias, water effects or contamination.

3P.3—Experimental design and method evaluation question 1

[Maximum number: 2]

Flowering plants produce seeds that can be stored in a seed bank. This is done to conserve the biodiversity of plants.

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.

The graph does not show the standard deviations of the means for mitotic index.

Describe how the investigation could be modified to allow standard deviations to be obtained.

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