chapter+9

p. 99 DBQ: effect of temperature by data-logging.

Note: students may need background information on the effect of dissolved carbon dioxide in water, namely, that as the carbon dioxide concentration increases, the pH goes down; as CO2 concentration decreases, pH goes up.
 * 1) pH was monitored to measure the uptake of CO2 by the pondweed.
 * 2) Temperature is the independent variable (note the title: “the effect of temperature”); pH is the dependent variable.
 * pH, the dep. var. should go on the y-axis. The independent variable normally goes on the x-axis. If pH were only measured after one hour, then temperature, the independent variable, would be on the x-axis. However, because we measured pH at several time points, one way to graph this would be to put time on the x-axis, and have 5 separate curves for the 5 different temperatures.
 * 1) The optimum temperature appears to be about 25.0 degrees.
 * 2) Different species of algae have different optimal temperatures, e.g., tropical versus temperate algae.
 * 3) Narrow range of temperatures were tested; expand the range to cooler and warmer temperatures. Light source was presumably constant, but not shown in diagram.

DBQ, Chapter 9, p. 100: photosynthesis rates in red light 6 CO2 +12H2O → glucose + 6O2 +6H2O in which case the answer would be 12 photons to derive 12 electrons from the 12 water molecules?] Each electron has to be excited twice before reducing NADP+: once at photosystem II and once at photosystem I.
 * 1) Wavelengths of 660 and 670 nm produce same amount of oxygen as 650 (0.14 molecules); yield declines slightly at 680, drops precipitously thereafter [note: there appears to be an error in the graph, with two circles at 680 nm instead of just one.]
 * 2) With supplementary light, light is not a limiting factor.
 * 3) Overlapping error bars at 660 and 670 show that the yield is about the same; only becomes different at 680 and thereafter.
 * 4) 1 molecule/(0.125 molecules/photon) = 8 photons.
 * 5) [Not sure what is meant here. Are we to use the equation