Before Watson and Crick presented their work, the scientific community understood that proteins and genes are interrelated and that genes may be located on chromosomes but were not able to point out genes as having locations. The role of DNA was also thought to be extremely insignificant, and it was viewed simply as a binding molecule within the cell.
I think the veins absorb the photons because they're located at the top part of a leaf while the stomata that serves as the leaf's lungs are found at the under side.
