Courses
Courses for Kids
Free study material
Offline Centres
More
Store

# Which one of the following equation suggest that ${ O }_{ 2 }$ released during photosynthesis comes from watera) $6C{ O }_{ 2 }^{ 18 }+12{ H }_{ 2 }O\longrightarrow 6{ O }_{ 2 }^{ 18 }+{ C }_{ 6 }{ H }_{ 12 }{ O }_{ 6 }+6{ H }_{ 2 }{ O }^{ 18 }$b) $6C{ O }_{ 2 }+12{ H }_{ 2 }{ O }^{ 18 }\longrightarrow 6{ O }_{ 2 }+{ C }_{ 6 }{ H }_{ 12 }{ O }_{ 6 }+6{ H }_{ 2 }{ O }^{ 18 }$c) $6C{ O }_{ 2 }^{ 18 }+12{ H }_{ 2 }{ O }\longrightarrow 6{ O }_{ 2 }^{ 18 }+{ C }_{ 6 }{ H }_{ 12 }{ O }_{ 6 }+6{ H }_{ 2 }{ O }$d) $6C{ O }_{ 2 }+12{ H }_{ 2 }{ O }^{ 18 }\longrightarrow 6{ O }_{ 2 }^{ 18 }+{ C }_{ 6 }{ H }_{ 12 }{ O }_{ 6 }+6{ H }_{ 2 }{ O }$

Last updated date: 20th Jun 2024
Total views: 404.1k
Views today: 6.04k
Verified
404.1k+ views
Hint: Photosynthesis is an anabolic process by which chloroplast of green plants and other phototroph’s synthesize carbohydrate (glucose) and evolve molecular oxygen as a by- product, using $C{ O }_{ 2 }$, ${ H }_{ 2 }{ O }$, and sunlight.

Complete Step by Step Answer:
- Photosynthesis is chemically a redox reaction in which water is oxidized and carbon dioxide is reduced.
- Till 1930 it was believed that photosynthesis is just the reverse of respiration
$6C{ O }_{ 2 }+6{ H }_{ 2 }{ O }\xrightarrow [ Light ]{ Chlorophyll } { C }_{ 6 }{ H }_{ 12 }{ O }_{ 6 }+6{ O }_{ 2 }$
- An experiment conducted by Ruben and Kamen in 1940 proved that oxygen evolved during photosynthesis comes from water, not from $C{ O }_{ 2 }$ for the experiment they used heavy radioisotopes of oxygen in the water and $C{ O }_{ 2 }$.
- In experiment 1 when photosynthesis occurs in the presence of ${ H }_{ 2 }{ O }$ and $C{ O }_{ 2 }^{ 18 }$ the heavy isotopes were found in the evolved ${ O }_{ 2 }$
$C{ O }_{ 2 }+2{ H }_{ 2 }{ O }^{ 18 }\xrightarrow [ Light ]{ Chlorophyll } { C }_{ 6 }{ H }_{ 12 }{ O }_{ 6 }+{ H }_{ 2 }{ O }+{ O }_{ 2 }^{ 18 }$
- In experiment 2, when photosynthesis occurs in the presence of normal ${ H }_{ 2 }{ O }$ and $C{ O }_{ 2 }^{ 18 }$, the isotopic oxygen is not evolved
$C{ O }_{ 2 }^{ 18 }+2{ H }_{ 2 }{ O }\xrightarrow[ Light ]{ Chlorophyll } { C }_{ 6 }{ H }_{ 12 }{ O }_{ 6 }^{ 18 }+{ H }_{ 2 }{ O }^{ 18 }+{ O }_{ 2 }$
- The experiment for the first time proved that the oxygen evolved during photosynthesis comes from water.
- Then the conventional equation was modified as a molecule of ${ H }_{ 2 }{ O }$ is not sufficient for the evolution of 6 molecules of $C{ O }_{ 2 }$, now the correct balanced equation of photosynthesis is
$6C{ O }_{ 2 }+12{ H }_{ 2 }{ O }^{ 18 }\longrightarrow 6{ O }_{ 2 }^{ 18 }+{ C }_{ 6 }{ H }_{ 12 }{ O }_{ 6 }+6{ H }_{ 2 }{ O }$.
So,the correct answer is (d), ”$6C{ O }_{ 2 }+12{ H }_{ 2 }{ O }^{ 18 }\longrightarrow 6{ O }_{ 2 }^{ 18 }+{ C }_{ 6 }{ H }_{ 12 }{ O }_{ 6 }+6{ H }_{ 2 }{ O }$”.

- Chlorophyll absorbs solar energy. It is this energy that is used to split water molecules into hydrogen and oxygen then oxygen is released from the leaves into the atmosphere. Hydrogen and $C{ O }_{ 2 }$ are used to form glucose or food for plants.
(2) $C{ O }_{ 2 }$ Levels: Increasing the level of $C{ O }_{ 2 }$ stimulates photosynthesis.