2. Regarding Phases 2 or 3 of the experiment, if more or fewer drops of Reagent D (sodium hydroxide) were needed to get the same blue color as in Phase 1, what does this tell us about the quality of the water when yeast was consuming nutrients in the water? Did something similar to eutrophication occur?

Phase two need 5 drops and phase 3 need 2 drops

The water quality is deteriorated as there is depletion in Oxygen O₂.

Yes, the activity of the yeast has precluded the usage of the water

Explanation:

Here, we note that the addition of more or fewer drops of Reagent D sodium hydroxide (NaOH) is required to get the same blue color as in Phase 1 where no yeast is added indicates the level of O₂ in the water as the amount of O₂ concentration in the solution is directly proportional to the amount of Reagent D required to reach blue, meaning the O₂ is depleted.

When less sodium hydroxide is required to turn blue we have depleted sodium hydroxide in the solution that is the yeast added in Phases 2 or 3 of the experiment, consume O₂

Eutrophication is the enrichment of a body of water with nutrients that results in a change in the ecosystem such as: algae production, oxygen depletion and other results that diminishes the water usage.