IB Biology Practical Investigations/Cells/Population growth of yeast cells

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Background information for teachers[edit]

(This practical is placed here more as a bookmark than as a real example of work. I am still testing out this wiki idea. Steve).


This simple practical is good in the early stages of the DP Bio course as an introduction to the IA methods and write-up procedure. Students are given a culture of yeast cells in sugar and water, a microscope and a haemocytometer. The method is given to them, so it is not suitable for Planning (a) or Planning (b).


Instructions[edit]

AIM: To produce a population growth curve of yeast cells in liquid nutrient medium.


MATERIALS AND EQUIPMENT:

  • Activated yeast culture
  • Microscope and haemocytometer
  • Incubator
  • Dropping pipettes, distilled water, 1 x 100ml beaker.


METHOD IN BRIEF:

  • Instruct students in use of the haemocytometer and calculations required.
  • Cell counts are made on a daily basis for 1 week, and recorded on a population growth curve.

Teachers' Reflections[edit]

Having tried this practical a number of times, I have found it useful for diagnosing new DP students' lab skills, approaches to the write-up procedure and graph-drawing skills. Naturally, as a first 'assessed' practical, it wouldn't normally be considered for moderation, though in some cases it has been completed to a high standard. Steve