Respiration

The volumes come from a teaching model of typical results, not from real yeast. Real yeast differs in how active it is, so real volumes differ; the pattern, fastest at about 35 to 40 °C and very little at 60 °C, is typical.

Some of the gas collected while a tube settles is air pushed out as the tube warms, so only the 5 timed minutes are counted. Yeast may use up a little oxygen left in the tube first; after that it respires without oxygen. Yeast also takes a few minutes to get going, and some of its first carbon dioxide dissolves in the solution, so the readings after settling are lower than the timed rates alone would give.

Time runs much faster than real time: each 10 minutes to settle and each 5-minute run pass in a few seconds. Between steps the model waits while you read.

With reduced motion each step is drawn complete at once.