Phenotypically and genotypically there are only two different ratios. If you think of a Punett square...
<span>You could say that a pea plant with the trait for the dominant color green (G) could also carry the recessive trait for yellow (g). So let's say you mate a dominant green, (Gg) with another dominant green, (Gg). You would get 1 (GG), 2 (Gg) and 2 (gg). </span>
<span>Phenotypically (as in physical traitwise), the ratio is 3:1 because you have 3 green colored peas and one yellow. </span>
<span>Genotypically (as in traitwise), the ratio is 1:2:1, because you have 1 (GG), 2 (Gg) and 1 (gg). </span>
<span>So although it's random, for any specific trait there are only 4 different outcomes.</span>
I believe the answer for your question is a mitochondria.
The fresh water is in a very big minority when compared to the total amount of water reserves on the planet.
The freshwater accounts for only 2%, while the rest of the 98% are saline water.
But the available freshwater for usage is even less, as from those 2% around 87% is frozen in the ice caps and the glaciers. Around 12% is groundwater, and not all of it is suitable for usage, and only 1% is the freshwater that is the most available from the rivers and the lakes.
This makes the freshwater a prime thing for preservation, as it is what enables the life on the planet, so much more measures have to be undertaken for it to be clean and in healthy condition.
