Question

Consider the diagram below which represents photosynthetic reactions. Choose the option that correctly matches the names to the labels (i), (ii), (iii). Also, the option must match for the involvement of chlorophyll in - (a) Light reaction or (b) Calvin-Benson Cycle.

• A. (i) Water, (ii) Oxygen, (iii) Carbon dioxide; chlorophyll is used in a-Light reactions
• B. (i) Carbon dioxide, (ii) Oxygen, (iii) Water; chlorophyll is used in a-Light reactions
• C. (i) Oxygen, (ii) Water, (iii) Carbon dioxide; chlorophyll is used in b-Calvin Benson cycle
• D. (i) Water, (ii) Carbon dioxide, (iii) Oxygen; chlorophyll is used in b-Calvin Benson cycle

Answer 1

The correct option is A

(i) Water, (ii) Oxygen, (iii) Carbon dioxide; chlorophyll is used in a-Light reactions

The first part of the diagram depicts the light reaction in which water is used along with NADP and ADP and gets converted into oxygen, NADPH, and ATP. NADPH and ATP are both compounds that store energy. Therefore, (i) is water and (ii) is oxygen. Chlorophyll is involved in the light reaction to harness sunlight for the splitting of water molecule into it's constituent components oxygen and hydrogen.
The next part of the diagram depicts the Calvin-Benson cycle which is a part of the dark reaction. Here, carbon dioxide gets fixed i.e. converted into more complex molecule i.e. glucose. Therefore (iii) is carbon dioxide.