Respiration In Plants Notes For NEET
Plants unlike animals have no special systems for breathing or gaseous exchange. Stomata and lenticels allow gaseous exchange by diffusion. Almost all living cells in a plant have their surfaces exposed to air. The breaking of C-C bonds of complex organic molecules by oxidation cells leading to the release of a lot of energy is called cellular respiration. Glucose is the favoured substrate for respiration. Fats and proteins can also be broken down to yield energy. The initial stage of cellular respiration takes place in the cytoplasm. Each glucose molecule is broken through a series of enzyme catalysed reactions into two molecules of pyruvic acid. This process is called glycolysis. The fate of the pyruvate depends on the availability of oxygen and the organism. Under anaerobic conditions either lactic acid fermentation or alcohol fermentation occurs.
Fermentation takes place under anerobic conditions in many prokaryotes, unicellular eukaryotes and in germinating seeds. In eukaryotic organisms aerobic
respiration occurs in the presence of oxygen. Pyruvic acid is transported into the mitochondria where it is converted into acetyl CoA with the release of CO2. Acetyl CoA then enters the tricarboxylic acid pathway or Krebs’ cycle operating in the matrix of the mitochondria. NADH + H+ and FADH2 are generated in the Krebs’ cycle.
14.4 Kerbs’ Cycle
14.5 Electron Transport Chain
14.6 Respiractory Balance Sheet
14.7 Amphibolic Pathway
14.8 Respiratory Quotient