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PHOTOSYNTHESIS IN HIGHER PLANTS - Coggle Diagram
PHOTOSYNTHESIS IN HIGHER PLANTS
Photosynthesis
Physico-chemical process
Green plants use light energy to synthesis organic compounds.
Experiments related to photosynthesis
1. Variegated leaf experiment
Proves the necessity of chlorophyll for photosynthesis
2. Half-leaf experiment
Proves the necessity of CO2 for photosynthesis
3. Experiments of John Priestly (Bell jar experiment)
Led to the discovery of oxygen
4. Experiments of Jan Ingenhousz
Proves the necessity of sunlight for plants in order to purify the air
5. Experiments of Julius von Sachs
Proves that glucose is produced during the growth of plants and stored as starch
Proves that chlorophyll is present in chloroplasts
Proves that glucose is made in the green coloured areas of the leaves
6. Experiments of T.W Engelmann
Discovered the action spectrum of photosynthesis
It resembles the absorption spectra of chlorophyll a and b
7. Experiments of Cornelius van Niel
Inferred that oxygen evolved by photosynthetic plants is from water, not from CO2.
Chloroplasts
Site of photosynthesis
Present in the walls of mesophyll cells of leaves
Helps in receiving optimum quantity of incident light
Consists of a membranous system which has grana, stroma, lamellae, and fluid stroma
Pigments involved in photosynthesis
Chlorophyll a: Bright blue/green
Chlorophyll b: Yellow green
Xanthophyll: Yellow
Carotenoids: Yellow to yellow-orange
Accessory pigments: Chlorophyll b, xanthophyll, carotenoids
Protect chlorophyll a from photo-oxidation and absorb different wavelengths to transfer energy to chlorophyll a
Photosystems
PSI
Reaction centre absorbs lights till 700nm, and called P700
PSII
Reaction centre absorbs light till 680nm, and called P680
Each PS has a chlorophyll a & accessory pigments bound by proteins
One molecule of chlorophyll a forms a light harvesting complex (LHC)
Single chlorophyll a acts as the reaction centre