Question

Which of the following is the evidence to show that oxygen released in photosynthesis comes from water?

• A. Isotopic oxygen $\left(O^{18}\right)$ supplied as $H_{2}O$ appears in the $O_2$ released in photosynthesis.
• B. Activated chloroplast in water releases $O_2$ if supplied potassium ferrocyanide or some other reducing agent in the absence of $C{O}_2$.
• C. Photosynthetic bacteria use $H_{2}S$ and $C{O}_2$ to make carbohydrates, $H_{2}S$ and sulphur.
• D. All of the above.

Answer 1

The correct option is D All of the above.

• Ruben and Kamen in 1941 using Chlolerra a green alga proved it by using isotopes of oxygen ${}^{18}O$ in water and gave the result that oxygen is released by green plants is obtained by photolysis ow water.
• Robin Hill showed that isolated chloroplast present with an electron acceptor and potassium ferricyanide release oxygen without the absorption of water. Hence proved carbon dioxide does not provide it.
• In 1930, C.B. Van Niel proved that sulphur bacteria use H${}_2$S and release sulphur

So the correct option is 'All of the above.'