Photos with Different Extremes

The first picture is one where I made the background lighter by having the ISO at 125, the aperture was at f/9.  This made the picture lighter even though it was starting to get dark out.  The second picture is of the same flowers but with an ISO of 500 and still an aperture of f/9 to make the picture look really dark.  Looking at these two side by side you can really tell the difference.  The third and fourth pictures are messing with the Aperture.  For the third picture, I made the aperture f/3.8 and the ISO 125 so it was really low, making the center flower in the plant clear and the background blurry.  For the same plant I used an aperture of f/10 and the ISO 125, making the whole plant much more clear instead of just one thing clear.