$6 C O_{2} + 12 H_{2} O L i g h t \to C_{6} H_{12} O_{6} + 6 H_{2} O + 6 O_{2}$ .
where $C_{6} H_{12} O_{6}$ represents glucose. The $O_{2}$ released is from water; this was proved using radio isotope techniques. Note that this is not a single reaction but description of a multistep process called photosynthesis. Can you explain why twelve molecules of water as substrate are used in the equation given?

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Solution

Products of light reaction required in dark reactions to form one molecule of glucose are 12 molecules of NADPH and 18 molecules of ATP.
For forming 2 molecules of NADPH from NADP+, 2 molecules of water are required so that demand of 4 electrons and protons can be satisfied.
Two molecules of water split to form 1 molecule of oxygen and the respective number of electrons and hydrogen ions are also formed.
So, for producing 12 molecules of NADPH, a total of 12 molecules of water are required.

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Similar questions

6 C O_{2} + 12 H_{2} O L i g h t - -- \to C_{6} H_{12} O_{6} + 6 H_{2} O + 6 O_{2}

where

C_{6} H_{12} O_{6}

represents glucose. The

O_{2}

released is form water ; this was proved using radio isotope techniques. Note that this is not a single reaction but description of a multistep process called photosynthesis. Can you explain why twelve molecules of water as substrate are used in the equation given above ?

Q. Can you explain why twelve molecules of water as substrate are used in the equation given?

6 C O_{2} + 12 H_{2} O L i g h t \to C_{6} H_{12} O_{6} + 6 H_{2} O + 6 O_{2}

Question 27
Which of the following equations is the summary of photosynthesis?

(a) $6 C O_{2} + 12 H_{2} O \to C_{6} H_{12} O_{6} + 6 O_{2} + 6 H_{2} O$
(b) $6 C O_{2} + H_{2} O + S u n l i g h t \to C_{6} H_{12} O_{6} + O_{2} + 6 H_{2} O$
(c) $6 C O_{2} + 12 H_{2} O + C h l o r o p h y l l + S u n l i g h t \to C_{6} H_{12} O_{6} + 6 O_{2} + 6 H_{2} O$
(d) $6 C O_{2} + 12 H_{2} O + C h l o r o p h y l l + S u n l i g h t \to C_{6} H_{12} O_{6} + 6 C O_{2} + 6 H_{2} O$

Q. In photosynthesis, 6 molecules of carbon dioxide combine with an equal number of water molecules through a complex series of reactions to give a molecule of glucose having a molecular formula

C_{6} H_{12} O_{6}

. How many grams of water would be required to produce 18 g of glucose? Compute the volume of water so consumed assuming the density of water to be

1 g c m^{- 3}

.
Rreaction that takes place during photosynthesis is:

6 C O_{2} + 6 H_{2} O

⟶

C_{6} H_{12} O_{6} + 6 O_{2}

Photosynthesis of a carbohydrate in plants is given by chemical equation:

6 C O_{2} + 6 H_{2} O ⟶ C_{6} H_{12} O_{6} + 6 O_{2}

If you have net result as:

6 C O_{2} + 6 H_{2} O ⟶ C_{6} H_{12} O_{6} + 6 O_{2}

Check whether this reaction is correct or not.

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