During the photosynthesis 02 that is released from the plants is generated from what?

water (H2O); during the light-dependent reactions (the first half of photosynthesis), water does the following roles: it replaces used electrons, contributes hydrogen ions into the thylakoid space, and releases an oxygen molecule as a byproduct.

the sugar-phosphate backbone forms the structural framework of nucleic acids, including dna and rna. this backbone is composed of alternating sugar and phosphate groups, and defines directionality of the molecule.