94 



PROBLEMS IN PHOTOSYNTHESIS 



It follows from the first three values that 



h' = 7.0 + 1.0 + 3.5 = 11.5 mm 

 li = 4.0 + 0.5 + 1.5 = 6.0 mm 



and hence 



xo, = +29.6 jul -vro, = -30.0 /xl 

 From the last three values it follows that 



7 = -1.0 



h' = 10.0 + 3.5 - 1.5 = 12.0 mm 

 h = 5.5 + 1.0 - 0.5 = 6.0 mm 



and hence 



Xo, = +33.4 m1 .vco, = -36.0^1 7 = -1.08 

 Thus, the average value for the O2 capacity is 31 .5 /xl so that 



O2 capacity _ 31.5 



chlorophyll content 29.2 



= 1.08 



In Example a the cells used contained 6.4% chlorophyll (200 //I cells = 50 

 mg dry weight) ; in Example b, where the ratio of O2 capacity and chlorophyll 

 content was 1, Chlorella contained only 2.34% chlorophyll. It has been 

 established that the ratio 1 is valid for a chlorophyll content up to 5%t of 



Ml 

 O2 



23.4 



min- 



Eig. 37. Stoichiometric oxygen production (oxygen capacity) from Chlorella. Constant 

 light intensity. End value: 23.4 ^ul = 1.045 iJ.mo\e O2. Chlorophyll content: 22.8 lA = 

 1.1018 Atmole (Warburg et a I., Naturw.). 



the cell dry weight. Figure 37 depicts the stoichiometric O2 production in 

 the form of a graph. Oo production is initially rapid but becomes slower 

 and slower and reaches its end value after 5 min. In this experiment the 

 end value is 23.4 lA Oo. Thus, under the influence of light, 23.4 jA = 1.045 

 /xmole O2 have been produced by 100 jA cells. The chlorophyll content of 

 the cells used is 1.018 /xmole. 



When the chlorophyll content of the cells is decreased to V2 or Vt — by in- 

 creasing the light intensity during cultivation — O2 capacities decrease in the 

 same proportion. Warburg (58) concludes that the O2 must originate from 



