<em>It was important that Mendel did not limit his study to just the F1 generation because parental traits that were not observed in the F1 reappeared in the F2.</em>
For example, in across involving a true-breeding yellow seedcoat pea plant and a true-breeding green seedcoat pea plant, all the F1 offspring would be yellow provided that the yellow seedcoat is dominant over the green seedcoat. The green seedcoat trait will only reappear in F2 offspring.
<u>If the breeding experiment is limited to just the F1 generation, of course, the parental green seedcoat trait will not surface at all. </u>
Respiratory system, because the lungs and diaphragm would get the oxygen from the air, and transfer them to the circulatory system (that's a pretty basic explanation, there's much more to it)
