MECHANISM OF PHOTOSYNTHESIS

MECHANISM OF PHOTOSYNTHESIS

The process of photosynthesis is summed up in the word and chemical equation below:
carbon dioxide + Water  Glucose + Oxygen
(Raw materials)         sun light and   (Products)
                               Chlorophyll.
                              Sun light
6CO₂ (g)+ 6H₂0 (l) C₆H₁₂O₆ + 6O₂
                            Chlorophyll

Photosynthesis occurs in two phases; namely light- dependent stage (light reaction/ stage) and light independent stage (dark reaction/stage.)
Light – dependent stage
Radiant energy is absorbed by chlorophyll. The chlorophyll is activated and it converts light energy into chemical energy in the form of ATP. [Adenosine Triphosphate]
Water is split into hydrogen ions and hydroxyl ions.
      Light
H₂O   [ H ]⁺ + [OH]¯
     Chlorophyll
Oxygen gas is formed from reactions, involving hydroxyl ions.
The products of the light dependent stage are ATP, H⁺ ions and oxygen.
Light independent stage
The hydrogen ions and chemical energy that were produced during the light dependent phase are used to reduce carbon dioxide to form glucose.

MACRO AND MICRO NUTRIENTS

Table : Macro and micronutrients and their uses.

Macro nutrients	Uses	Deficiency
Nitrogen	Amino acid and protein synthesis	- Chlorosis with purple colourings
Phosphorus	Protein formation	- Reddish purple leaves and stunted growth.
Sulphur	Formation of certain amino acids	- Stunted growth - yellow patches on leaves
Calcium	Formation of cell wall (middle lamella)	- Poor development of leaves at shoot apex
Potassium	Concerned with synthesis of carbohydrates and protein metabolism in young leaves.	- Chlorosis, and yellowing of leaves at the margins, tips. - Retarded growth.
Magnesium	Chlorophyll formation. Facilitates enzyme activity.	- Chlorosis of older leaves. - Stunted growth.
Iron	Required for the formation of chlorophyll but not part of the molecule.	- Chlorosis with pale leaves
Micro nutrients Cobalt Copper Zinc Manganese Boron	They are necessary for the manufacture of enzymes.	- Stunted growth of leaves.