Well done on these images. This will be a lengthy post because I believe there's a lot of potential here. I understand you cannot carry out much post-processing for the exam, but do consider this critique if you want to revisit these images post-your exam. All the comments below will take this into account.
Starting from v2... V2 is my favourite, but John's critique above is spot on - I think the missing edge there, excuse the pun, is the edge of the leaf. The composition would have improved if we could follow the leaf from the bottom left, follow the diagonal till the edge of the leaf and then maybe travel back towards the starting point by following the out of focus areas. Without the edge of the leaf, our eyes "end" the movement on the frame, and I don't think this is something you should aspire to.
Also, speaking of the frame, I would probably go for colours that are a bit more contrasting, at the very least in the inner colour. For instance, I prefer the colour choices made for the frame in V1, as the white portion separates the frame from the image, whilst the green complements it. In V2, however, this aspect is missing as both colours used in the frame are very similar to the subject matter. Coupled with the "edge of the leaf" issue above, this might detract from the quality of the final presentation, in my opinion of course. I think if you retake V2 and ensure that the composition includes the leaf's edge (on RHS), and adjust the frame colours to say white (internal) and green (external) or white/black for instance for added contrast, then the end-result would be a much better photo.
As regards V1, it's a well spotted abstract. I would also consider going lower and aiming the camera higher, trying to get those curled edges to look more 3D. Some creative use of lighting might also introduce a bit of shadow elements that help make the image "pop" a bit more. The frontal view doesn't permit this as much. Moreover, this approach would probably eliminate the diagonal in the background - we tend to follow lines but that line isn't helping much being on the RHS, going from top to bottom, and leading away from the subject. I would have tried to avoid such a line in the composition so as to retain attention on the "comb-like" effect that you clearly wanted to achieve with this image. Regardless, it's still a nice abstract.
Finally, as regards v3, I think if you revisit this image and carry out some minor post-processing, I would clone out that black dot in the middle as it is distracting, and I would finish off by rotating the image towards the right by a couple degrees (as necessary) to straighten the middle line. Potentially, I'd go for a square crop and position the vertical on a third, left or right, for a more abstract look. I like the texture on this one, and how the lines move across the leave in a shape similar to waves.
All in all, there's a LOT of potential in these images, and they're all well taken. With a little bit of care though, and in a context where you could do some post-processing, you will end up with an even better set, and I look forward to seeing such a set if you take up these suggestions and revisit this work.
Regardless of the above, well done and good luck on your exam, and hope you didn't mind my critique. Take care!