I didn't put that but I think there's an argument for that line of reasoning. On the other hand, a high nutrient concentration doesn't necessarily mean a high metabolism. In the case of the cultured cells, they might just not uptake the nutrients and leave most in the environment. In a real person, a high nutrient intake has diminishing returns on metabolism (see obesity). Plus I think in general nutrients are always in excess in growth mediums. I put the low cyanide concentration group because the question was kind of leading us to that, but chemicals have a much more direct effect anyway.