In the Beginning was Information

glucose is produced from 6 mol CO 2 and an input of 2,872.1 kJ of energy.each and every energy conversion, the actual quantity of light energyrequired is greater. Red light quanta possess less energy (about 2 eV/lightquantum) than blue light quanta (approx. 3 eV/quantum), but both typesproduce approximately the same amount of photochemical work. It hasbeen determined experimentally that 8 to 10 light quanta are required forevery molecule of CO 2 . The energy content of 1 mol of red light quanta(= 6.022 x 10 23 quanta 27 ) is given by 171.7 kJ. Therefore 9 mol of red lightquanta (the average of 8 and 10) is found by multiplying 171.7 kJ x 9. Theresult is 1,545.3 kJ. The efficiency Ë can be calculated as the ratiobetween the theoretical amount of energy required to assimilate 1 molCO 2 (478.7 kJ) and the actual energy content of the incident red light(1545.3 kJ):Ë red = 478.7/1,545.3 x 100 % = 31 %The energy content of blue light quanta is 272.1 kJ/mol, so it followsthat Ë blue = 20 %.Volume of photosynthesis: The productivity of plants is not only qualitativelybut also quantitatively highly impressive. A single beech tree whichis 115 years old has 200,000 leaves which contain 180 grams of chlorophylland have a total area of 1,200 m 2 , and can synthesise 12 kg of carbohydrateson a sunny day, consuming 9,400 litres of CO 2 from a total volumeof 36,000 m 3 of air [S4]. Through the simultaneous production of9,400 litres of oxygen, 45,000 litres of air are ‘regenerated’! On a worldwidescale 2 x 10 11 tons of biomass is produced annually by means ofphotosynthesis [F6]. The heat value of this mass is about 10 14 Watt-years(= 3.15 x 10 21 Ws). The entire human population annually consumes about0.4 TWa = 1.26 x 10 19 Ws (1 TWa = 1 Terawatt-year = 3.1536 x 10 19 Ws),and all the animals require 0.6 TWa. Together these add up to only onepercent of the total annual biomass production.Respiration: The result of breathing, namely the release of energy, is theopposite of photosynthesis. These two processes are in ecological equilibrium,so that the composition of the atmosphere stays constant, unless it is27 The enrgy equivalence of light quanta: According to the law of Stark and Einstein(the law of the equivalence of quanta), one photon with energy h x v can excite onlyone molecule (h is Planck’s constant and Ó is the frequency of the light waves). Sinceone mol of any substance consists of 6.022 x 10 23 molecules, it means that the amountof energy required for this excitation or conversion process, is given by E = 6.022 x10 23 x h x Ó. This quantity of energy is called the photochemical equivalent (= 1 Einstein= 1 mol of quanta). The energy equivalence of light quanta (photons) is not constant,but depends on the wave length Ï = c/Ó so that it is usually given in molar units.The number of photons in 1 mol of light is identical to the Avogadro number N A .232