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1) Can you make any observations about how the system behaves?
I set all the constants to somewhat random numbers and played around with the growth rate, and the initial cells and nutrients. If the growth rate was set high, the nutrients would be used up more quickly. Once all of the nutrients were used up, the cells started to die. If the growth rate was set high, the population would grow quickly, use all the nutrients up, and then die quickly. If the growth rate was set slower, the nutrients were used up more slowly, allowing the population to live for a longer time (although at smaller numbers) and then they died slower.

2) Can you make any observations about how the system behaves?
The logistic curve simulates a carrying capacity on the population. The limiting factor for the growth of the cells depended on either the carrying capacity or the nutrients available. I started by setting the carrying capacity low; in this case, the cells reached their carrying capacity well before the nutrients were used up. The cells stayed at this level until the nutrients ran out, and then they decreased in numbers. When the carrying capacity was set high, the cells grew until the nutrients ran out. This was well before the carrying capacity was reached.

3) For example, look at the nutrient dependent growth rate in the Malthus model.  Or, think about the waste products the yeast might produce.  Are any of them toxic to the yeast?  Where might that lead?
Most waste products are toxic to organisms. If the waste was toxic to the yeast which I think it would be, it would lower the overall growth rate by causing more cell death. This would lead to a slower growth rate because the growth rate is equal to the births minus the deaths of the cells. Once the cells die because of the toxic waste, I think there would be less toxic waste so the yeast cells would once again start growing again. This might not be true, however, because this is assuming the toxic waste is somehow removed.


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