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Photosynthesis

It is the process by which producers of the ecosystem fix atmospheric Carbon dioxide (CO2) from otherwise unavailable, inorganic, gaseous state of carbon(C) to usable organic form (carbohydrates).
 
Many organisms can carry out photosynthesis, including both prokaryotic and eukaryotic Organisms for, eg. Cyanobacteria, Green Sulfur bacteria, Green non-sulfur bacteria etc. and
Algae, Plants respectively.
 
If we want to describe photosynthesis in layman's language, then it can be described as a word made up of 2 subwords that is photo + synthesis.
Where Photo= sunlight and Synthesis= to prepare something.
 
Thus photosynthesis is simply a process of preparation of the organic form of carbon (Carbohydrates) in the presence of sunlight or using energy from the sunlight and atmospheric CO2 as raw material.
 
Thus producers like plants and photosynthetic bacteria, bring the unusable form of C from the atmosphere to living system in a usable organic form.

 
Photosynthesis can be of two types:

•     Anoxygenic photosynthesis
•     Oxygenic photosynthesis

Anoxygenic photosynthesis:
As the name indicates Anoxy + genic where: Anoxy= without Oxygen; genic= generation
thus the type of photosynthesis where Oxygen is not generated and not evolved in the environment during the process of photosynthesis is called as Anoxygenic photosynthesis.
 
This type of photosynthesis is ancient and is the first type of photosynthesis used to occur when the earth's environment was reductive in nature, and respiration type was anaerobic.
Eg. Purple sulfur bacteria, green sulfur bacteria etc.
 
Oxygenic photosynthesis:
As the name indicates Oxy + genic where: Oxy= Oxygen; genic= generation
thus the type of photosynthesis where Oxygen is generated and evolved in the environment during the process of photosynthesis is called as Oxygenic photosynthesis.
 
This type of photosynthesis evolved when some of the producers like cyanobacteria got the ability to use water as an electron donor for the light reaction of photosynthesis to occur. Thus with the photolysis of water (H2O), Oxygen was generated and added to the environment.
This made earth's environment to become Oxidative from reductive in nature and making room for aerobic respiration to evolve further. Eg. Cyanobacteria, Algae, Plants.
 
In my next post, I will be covering the mechanism of photosynthesis.
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Happy Learning
Shivani

 Practice only from those books which almost cover the entire syllabus of the exam. Students can also prefer NCERT books for preparations. Also solve the previous year question papers and compare your answers with the given solved papers. It will help you to understand your mistakes and difficult areas and after that you can work on it.