Question

Write the chemical reaction of photosynthesis and events occurred during the process.

Answer 1

In photosynthesis, green plants and certain other organisms like cyanobacteria, purple bacteria and green sulfur bacteria transform light energy into chemical energy. It is the primary source of all the food on Earth.

Complete step-by-step answer:
Photosynthesis reaction takes place in the chloroplasts through photosynthetic pigments like chlorophyll a, chlorophyll b, carotene and xanthophyll. In this reaction, nutrients are synthesized by using carbon dioxide, water and sunlight.
Chemical reaction of photosynthesis is -
$\underset { Carbon\quad dioxide }{ { 6CO }_{ 2 } } +\quad \underset { Water }{ { 6H }_{ 2 } } O\quad \xrightarrow [ Sunlight ]{ Chlorophyll } \quad \underset { Glucose\quad }{ { C }_{ 6 }{ H }_{ 12 }{ O }_{ 6 } } \quad +\quad \underset { Oxygen\quad }{ { 6O }_{ 2 } }$
There are several major events that occurred during the process-
-In the first step, Chlorophyll absorbs the light energy from the sun to split water molecules into hydrogen and oxygen. Water is absorbed by the root hairs from the soil and is carried to the leaves through the xylem vessels and Carbon dioxide enters through the stomata.
-Glucose is produced from carbon dioxide and hydrogen from water molecules in the presence of sunlight. The oxygen is liberated as a byproduct through the leaves.
-Glucose provides energy for growth and development and is used as a source of food.
Photosynthesis occurs in two sequential stage:
Light dependent reaction
Light independent reaction (Dark reaction)
Light dependent reaction: Light reaction occurs in the presence of light in the thylakoid of the chlorophyll. Energy is produced in the form of ATP. The protein-bound pigment molecules form the light-harvesting complexes present inside two photosystems- PS-I and PS-II. Each photosystem has a reaction centre consisting of chlorophyll a molecule, and antennae containing accessory pigments.
The reaction centre for PS-I is P-700 because the absorption peak for chlorophyll a is at 700nm while that for PS-II is P-680 because the absorption peak for chlorophyll a is at 680 nm. These photosystems oxidize different sources of the low-energy electron supply. They deliver their energized electrons to different places and respond to different wavelengths of light.
Light independent reaction (Dark reaction): Dark reaction occurs in the stroma of the chloroplast. The dark reactions are sometimes called the Calvin cycle because of the cyclical nature of the process. In this reaction, energized electrons from the light-dependent reactions provide the energy to form carbohydrates from carbon dioxide molecules. Dark reactions do not use light as a reactant but they require the products of the light-dependent reactions to perform further reactions. This reaction also depends on the energy carrier molecules, ATP and NADPH, to drive the construction of new carbohydrate molecules.

Note:
-The photosystem I (PS I) uses ferredoxin-like iron-sulfur cluster proteins as terminal electron acceptors.
-The reaction center lies at the heart of a photosystem which is an enzyme that uses light to reduce molecules.