Physics and Astronomy

Mixed Company
Objective Identify cells and organisms.
Participants Teams of up to six.

Each team will be provided with a mixed culture of cells or organisms. The team will be required to prepare wet mount or hanging drop slides, identify as many cells or organisms as possible and be prepared to answer questions on their observations. A quantitative question will be included.


1. Team members may communicate with each other while the event is in progress and may share preparative and identification activities.
2. Books, prepared charts or other aids, except those provided, may not be used during the event.
3. Calculators and slide rules may not be used.

Judging Identification portion: 60 marks
Marks will be based on the number of correct identifications.
Quantitative portion: 40 marks
Correct answers, derived by the correct procedures, will score full marks. Part marks may be awarded.
Instructions to the Teacher

1. The students should learn proper and efficient microscope practice and the use of dichotomous keys. A team should be encouraged to divide responsibilities between slide preparation, microscopy, identification, etc.
2. We will plan on having 2 microscopes available for each team. All ' slides and other preparative materials will be provided.
3. Good sources of organisms are aquaria, pond water, etc. We will put together mixtures of protozoa and algae but may throw in a "ringer" or two. Keys will be provided, based on something like the "How to know" series: THE PROTOZOA, T.L. Jahn and THE FRESHWATER ALGAE, G.M. Prescott, Wm. C. Brown, Dubuque, Iowa. Our key will be a condensed form and probably will not include pictures or drawings.
4. Verification of identification may require drawings, answers to specific questions or visual verification by judges. This remains to be worked out.
5. Quantitative questions will most likely involve dimensions (lengths, cell volume, population densities, etc.) based on knowledge of field diameters and magnifications.

Source London District Science Olympics. This event was designed by Tom Haffie

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