Hill's reaction in photosynthesis demonstrates that:

The first important biological investigation which led to the conclusion that plants make their substance from water and not from soil was carried out by

The hypothesis that all photosynthetic organisms require a source of hydrogen was first proposed by

Theodore $W$. Engelmann illuminated a spectrum on which alga to perform his classic experiment?

'Photosynthesis is the conversion of light energy within a plant' was first stated by

Which scientist used aerobic bacteria,a prism,and green algae in his experiment?