IB Biology Practical Investigations/Cells/Population growth of yeast cells
Background information for teachers 
(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).
AIM: To produce a population growth curve of yeast cells in liquid nutrient medium.
MATERIALS AND EQUIPMENT:
- Activated yeast culture
- Microscope and haemocytometer
- 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
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