A physico -chemical process by which they use light energy to drive the synthesis of organic compounds

primary source of food on earth responsible for release of oxygen into the atmosphere

Chlorophyll, light and CO2 are the requirement Experiment with leaf that was partially covered Experiment with KOH containing bottle

Bell jar experiment by Priestly (1770 Modified experiment with bell jar by Jan Ingenhouse

1854- Julius von Sachs- evidence for production of glucose T W Engelmann first action spectrum of photosynthesis Middle of 19 th century – the key features of plant photosynthesis CO2+ H2O [CH2O] + O2 Milestone contribution- Cornelius van Niel ( )- photosynthesis a Light dependent reactions and evoloved the formula 2H2A+ CO2 2A+ CH2O+ H2O

Rate of absorption wavelength

Rate of Photosynthesis wavelength

Photochemical phase – absorption, water splitting, oxygen release And formation of ATP AND NADPH2

Primary acceptor Pigment molecules Reaction centre Photon

2H 2 O4H + + O 2 + 4e - 2H 2 O 4H + + O 2 + 4e -

Light Chlorophyll P 700 Electron Transport System Electron Transport System e - acceptor

PHOTOSYSTEM II CYTOCHROMES b&f PHOTOSYSTEM I ATP synthase Thylakoid membrane Lumen Stroma

Ribulose 1,5 Biphosphate 3-phosphoglycerate Triose phosphate

Plasmodesmata PLASMA MEMBRANE CELL WALL HCO3-PEP FIXATIONREGENERATION C4 ACIDC3 ACID TRANSPORT DECARBOXYLATION C4 ACID C3 ACID ATMOSPHERIC CO2 CO2 C3 CYCLE

Photorespiration can occur when carbon dioxide levels are low, for example, when the stomata are closed to prevent water loss during drought. In most plants, photorespiration increases as temperature increases. Photorespiration produces no ATP and leads to a net loss of carbon and nitrogen (as ammonia), slowing plant growth. Potential photosynthetic output may be reduced by photorespiration by up to 25% in C3 plants. [2] [2]

If a chemical process is affected by more than one factor, then its rate will be determined by the factor which is nearest to its minimal value: it is the factor which directly affects the process if its quantity is changed.