Photosynthesis in Higher Plants – Notes

Photosynthesis
Photosynthesis is a physiochemical process in which light is used to prepare food.
Cornelius Van Niel found that photosynthesis is a light-dependent reaction in which a hydrogen atom reduces carbon dioxide to form carbohydrates.
He also inferred that water is the hydrogen donor which is oxidised O₂.
Chloroplast is found in the mesophyll cells of leaves.
The four pigments involved in photosynthesis are chlorophyll a, chlorophyll b, carotenoids and xanthophylls.

Light Reaction
Light reaction are the first stage of photosynthesis. It is the photochemical phase of photosynthesis.
Light reaction takes place in the thylakoid membranes inside the chloroplast. It includes photosynthetic pigments that are arranged into light-harvesting complexes within photosystem I and photosystem II.
Light reaction consists of the following four stages-light absorption, water splitting, release of oxygen and formation of high energy intermediates ATP and NADPH.
Water splitting contributes electrons that replace the electrons in PS II and protons that help in ATP synthesis.