An electrochemical demonstration of the energy cycle and maximum quantum yield in photosynthesis

Hydrostatic Pressure Effects on Photosynthesis

“…where p i s the heat of activation, k, and k, the reaction velocities a t two different temperatures, T , and T,. If the law is obeyed, the logarithm of the velocity varies with the reciprocal of the absolute temperature as a straight line relation of the sloge of , u (DAMASCHKE et al, 1953). I n this relationship, reaction velocity should increase continuously as temperature rises and never reach a maximum.…”

“…Polarographic detection of photosynthetically evolved oxygen has supplied much valuable information about photosynthetic processes (BLINKS and SKOW, 1938, BRACKETT et al, 1953, DAMASCHKE et al, (1953). Measurements of them were made under pressure by HAINSWORTH et al (1924) as early as 1924.…”

Use of a Glass Electrode for Measuring Rapid Changes in Photosynthetic Rates

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Recent measurements of photosynthesis in intermittent illumination with a period of 1 or 2 minutes revealed a hitherto unobserved phenomenon. These studies, carried out with algal suspensions in conventional manometer vessels, showed an extremely rapid initial apparent rate of photosynthesis in the light and a correspondingly rapid initial rate of respiration in the dark (Burk, 1953; Burk and Warburg, 1951). Some criticism of these experiments has been expressed on the grounds that the period of intermittency is not long enough for the establishment of a steady state transport of carbon dioxide and oxygen across the liquid-gas interface (Brown and Frenkel, 1953).

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Photosynthesis in Chlorella during Intermittent Illumination of Long Periodicity

“…These experiments are subject to criticism because it appears improbable that during periods as short as one minute the manometer can respond sufficiently rapidly so that the observed pressure changes represent the metabolic rates without the complication of physical lag. Subsequently Damaschke, T6dt, Burk and Warburg (2) determined the consumption and production of oxygen using an electrochemical method. Few results have yet been published; these show that after a period of illumination from 5 to 30 seconds the oxygen consumption immediately following the cessation of illumination was greater than in the preceding or subsequent steady state.…”

“…In the experiments of Brackett et al the cells were in the presence of air with 5 % carbon dioxide. With the hemoglobin method and with the convection polarographic method used by Damaschke, Todt, Burk and Warburg (2) the oxygen concentration ranges between 0.3 and 4.0 %. At these lower concentrations of oxygen photo-oxidative reactions are minimal.…”