Question

Oxygen liberated during photosynthesis comes from
(a) Water

(b) Chlorophyll
(c) Carbon dioxide
(d) Glucose

Answer 1

This substance is made up of hydrogen and oxygen in the ratio of 2:1. It exists in three states i.e. solid, liquid, and gases in the environment. It is very much essential for the existence of life on earth.

Complete answer:
The oxygen gas liberated during the process of photosynthesis comes from water. Photosynthesis is a process by which green plants prepare their own food by using carbon dioxide and water in the presence of sunlight. It occurs inside the chloroplast.
The reaction that occurs during photosynthesis is as follows:
$6{ C }{ O }_{ 2 }+{ 6{ H }_{ 2 } }{ O\longrightarrow }{ C }_{ 6 }{ H }_{ 12 }{ O }_{ 6 }+{ 6 }{ O }_{ 2 }$
During the process of photosynthesis, six molecules of carbon dioxide and six molecules of water react to form one molecule of glucose and six molecules of oxygen gas.

Additional Information:
- During the light reaction, the photolysis occurs in which splitting of water ${ H }_{ 2 }{ O }$ molecules takes place into a hydrogen ion ${ H }^{ + }$ and hydroxide ions $O{ H }^{ - }$, and these hydroxide ions $O{ H }^{ - }$ react to release Oxygen gas ${ O }_{ 2 }$.
- The green pigment chlorophyll present in the green plant is responsible for trapping the sunlight to provide energy for the photosynthetic process.
- Then the chlorophyll combines carbon dioxide $C{ O }_{ 2 }$ and water ${ H }_{ 2 }{ O }$ to form Glucose ${ { C }_{ 6 } }{ H }_{ 12 }{ O }_{ 6 }$.
- The carbon dioxide $C{ O }_{ 2 }$ we exhale is absorbed by the green plants through the tiny holes under leaves and also through flowers and branches.
- The end products of photosynthesis are glucose ${ { C }_{ 6 } }{ H }_{ 12 }{ O }_{ 6 }$ and Oxygen ${ O }_{ 2 }$ gas.
- This glucose ${ { C }_{ 6 } }{ H }_{ 12 }{ O }_{ 6 }$ is used up by the plant for energy and also stored as food.
- The oxygen ${ O }_{ 2 }$ is released by the process of respiration and also ATP is synthesized from glucose ${ { C }_{ 6 } }{ H }_{ 12 }{ O }_{ 6 }$ which is the energy for plants.
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So, the correct answer is, '(a) Water'.

Note:
- Life on earth is not possible without oxygen ${ O }_{ 2 }$ and water ${ H }_{ 2 }{ O }$ so photosynthesis is very much essential for the existence of life.
- The green pigment chlorophyll present in the green plant is responsible for trapping the sunlight to provide energy for the photosynthetic process.
- The oxygen ${ O }_{ 2 }$ is released by the process of respiration and also ATP is synthesized from glucose ${ { C }_{ 6 } }{ H }_{ 12 }{ O }_{ 6 }$ which is the energy for plants.
- To increase the amount of oxygen ${ O }_{ 2 }$ in the environment we should have to increase the number of plants so more plants have more oxygen available on earth.