Cellular Respiration and Photosynthesis
Big Ideas Cellular Respiration and Photosynthesis
Several experiments were conducted to understand better the physiological mechanisms underlying growth inhibition of the dinoflagellate Gonyaulax polyedra Stein due to small-scale turbulence shear. To measure photosynthetic C-14 uptake, a ''phytoplankton wheel'' device for rotating cultures in closed bottles was used. Turbulence was quantified biologically in the bottles by comparing growth inhibition with that in cultures with constant shear between a fixed cylinder and an outer concentric rotating cylinder (a stable Couette flow). At saturating irradiances, particulate photosynthesis (P-sat) or photosynthesis per unit chlorophyll (P-sat(B)) were not inhibited completely at the highest turbulence level (26.6 rad(.)s(-1)), and photosynthesis was less sensitive than growth. Photosynthesis per cell (P-sat(C)) was increased by turbulence. In three experiments on the effects of turbulence on photosynthesis versus irradiance curves, the slope of the curve, alpha, for particulate photosynthesis at limiting irradiances did not change. Photosynthesis per unit chlorophyll per unit irradiance (alpha(B)) decreased at high (but not intermediate) turbulence levels. Photosynthesis per cell per unit irradiance, alpha(C), increased with turbulence, suggesting an increase in photosynthetic efficiency in turbulent cultures. In two of the three experiments, respiration rates increased with turbulence, and in one experiment excretion of photosynthetically fixed C-14 was not affected by motion. Ratios of accessory pigments to chlorophyll alpha did not change with turbulence, but pigments per cell and per dry weight increased with turbulence These findings suggest little or no disruption of the photosynthetic apparatus. When turbulence was applied for 1 week, beta-carotene increased while peridinin and diadinoxanthin decreased, suggesting inhibition of synthesis of these latter pigments by prolonged turbulence. Since cell numbers did not increase or decreased during turbulent 72-h incubations, cell division was inhibited and also the cells were very much enlarged. Increases in alpha(C) per cell suggest that, in the sea, photosynthetic metabolism can persist efficiently without cell division during turbulent episodes. After turbulence ceases or reaches low levels again, cells can then divide and blooms may form. Thus, blooms can come or go fairly, rapidly in the ocean depending on the degree of wave- and wind-induced turbulence.
Aurum Science: Photosynthesis in Plant Cells
This process is also affected by the temperature surrounding the plant (the species of plant we experimented with, pond weed, photosynthesised best at around 20 degrees centigrade.) Light, temperature & CO2 are known as limiting factors, and each is as important as the next in photosynthes...
Artificial photosynthesis gets big boost from new …
The positive effect of photobiostimulation on animal cells is analogous to photosynthesis in plant cells, whereby a chain of chemical reactions are set in motion.