Summary of photosynthesis Concise Biology - icse

Biology-X
Photosynthesis

 Photosynthesis is a physiological process by which plant cells containing chlorophyll
produce food in the form of carbohydrates by using carbon dioxide, water and light
energy. Oxygen is released as a byproduct.



 Chlorophyll is the green pigment found in green plants.
 Chlorophyll is present in the thylakoids.
 Stomata are minute openings present in the epidermal layers of leaves. They are
responsible for the exchange of gases during photosynthesis.
 There are two theories for opening and closing of stomata: 1. Sugar Concentration
Theory: During the day time, as guard cells photosynthesise and produce sugar, the cells
become turgid. This causes the stomata to open. 2. K+ Ion Concentration Theory: The
stomatal opening and closing depends on the generation of a potassium ion gradient.
Increase in K+ ion concentration inside the guard cells causes stomata to open.
 Two main phases are involved in the mechanism of photosynthesis:




 Adaptation in Leaf for Photosynthesis:




 Factors Affecting Photosynthesis:
External Factors:Light Intensity,CO2, Temperature, Water content.
Internal Factor: Chlorophyll, Protoplasm, Structure of leaf.