Photosynthesis in Higher Plants Test - 6

Chloroplast contains stroma and grana. Stroma are involved in light independent reaction enzymes for synthesis of glucose molecules using proudcut of light reaction.

Photosynthesis occurs in two steps- light reaction and dark reaction. During light reaction ATP and NADPH molecules are formed and in dark reaction carbon dioxide is fixed.

Melvin Calvin awarded noble prize in 1960 for tracing the path of carbon during photosynthesis. The cycle of event is named after him as Calvin cycle.

Photorespiration in C₃ plants start with Phosphoglycolate as primary acceptor in presence of RUBP enzyme to form a two carbon compound and a three carbon compound.

The fact that C₃ plants respond to higher CO₂ concentration byshowing increased rates of photosynthesis leading to higher productivity .They are allowed to grow in carbon dioxide enriched atmosphere that leads to higher yields.

The CO₂ released in the bundle sheath cells enters the C₃ or the Calvin pathway, a pathway common to all plants. The bundle sheath cells are rich in an enzyme Ribulose bisphosphate carboxylase-oxygenase (RuBisCO), but lack PEPcase.

Breaking down of water molecules in presence of sunlight during photosynthesis is called photolysis of water. During photolysis of water reduction of NADP+ into NADPH takes place.

Ruben, Hassid and Kamen proved that Oxygen evolved during photosynthesis comes from water and not from carbon dioxide. For this, they used water with heavy isotope of oxygen, ¹⁸O.

First intermediate product produced in C₃ cycle of photosynthesis in presence of RUBP enzyme is 2-carboxy 3-keto 1,5-biphosphoribotol which change into two molecules of PGA.

Quantum yield is the number of Oxygen molecules released per photon or quantum of light. During light reaction of photosynthesis oxygen molecules are release during photolysis.