Who provided evidence for the production of glucose when plants grow?

If a photosynthesising plant releases oxygen containing more than the normal amount of $^{18}O$,it is concluded that the plant has been supplied with:

Moll's half leaf experiment was done to show ...................... was required for photosynthesis.

What does the experiment of two leaves explain in the context of photosynthesis?

One scientist cultured Cladophora in a suspension of Azotobacter and illuminated the culture by splitting light through a prism. He observed that bacteria accumulated mainly in the region of

Essentiality of $CO_2$ in photosynthesis can be demonstrated using