Who first suggested that light energy is converted into chemical energy within the plant body?

Isotopes popularly known to have been used in the study of photosynthesis are

Essentiality of $CO_2$ in photosynthesis can be demonstrated using

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

Two plants $A$ and $B$ are supplied with $CO_2$ with $H_2O^{18}$ and $CO_2^{18}$ with $H_2O$ respectively. Which of the following plants releases $O^{18}$ type oxygen in photosynthesis?

If a photosynthetic plant releases $18$ $O_2$ more than usual,what must the plant have received?