did Mendel explain this result?
We don't know
exactly how Mendel figured it out, but he probably tried several
ideas until he found the one that made sense. You can do it too.
Suppose that each plant has TWO trait controllers (Mendel did not
know about genes, or we would say two genes). He realized that something
in the plant controlled for pea color and that there must be two
controllers in the peas of each plant. In any plant, if either one
of the two genes is for green, the peas will be green, because green
is a dominant trait in peas. So how could you get a 3 to 1 ratio
of green peas to yellow peas? You assume that both parents have
one gene for green and another for yellow. The combination possibilities
predict a 3:1 ratio. Setting up a little table like the one
below shows how easy it is to see all the possible combinations.
Remember, anytime one of the two genes is for green,
the peas will be green because green is dominant over yellow. The
only way peas can be yellow is if BOTH genes control for yellow.