Question 3
Why is Tt twice as common in the F2 as TT?
The right answer is the one marked above.
Because there are two different ways to make Tt and only one to make TT. T can come from the ovum with t from the pollen, or the other way round. TT has only one route.
Dominance decides what the plant looks like. It has no effect at all on how often each pair of factors is formed.