Question

The oxygen evolved during photosynthesis comes from water molecules. Which one of the following pairs of elements is involved in this reaction?

• A. Magnesium and Chlorine
• B. Manganese and Chlorine
• C. Manganese and Potassium
• D. Magnesium and Molybdenum

Answer 1

The correct option is B

Manganese and Chlorine

The oxygen evolved during photosynthesis comes from splitting of the water molecules. ​​​​​​The splitting of water is carried out by the oxygen evolving complex. The complex is formed by manganese together with chlorine, calcium and bicarbonate ions.
​This phenomenon of breaking up of water into hydrogen and oxygen in the illuminated chloroplasts is called as photolysis or photocatalytic splitting of water.