Have students inspect the data. They need to analyze the data for changes in the laboratory variable(s) they studied. They can also look for other changes that might correlate to photosynthesis or respiration. Is there a pattern in the data?
“In fact, the charge migration happens faster than the time resolution of our instrument, and probably involves short-lived, high-energy excited states.” The researchers plan to seek a collaborator with faster instrumentation who can measure the exact rate of charge separation to help clarify the mechanism.In a follow-up experiment, the scientists performed the transient absorption measurement under photocatalytic operating conditions, with a reagent used as the ultimate source of electrons to produce hydrogen (a scalable artificial photosynthesis of hydrogen fuel from water would require replacing the reagent with electrons released during water oxidation).
When teaching units on and or the , direct evidence of their occurrence is sometimes difficult to provide in a compelling form the laboratory. This exercise allows students to work directly with organisms and, via RUSS, an entire lake . Increasing concentrations in student built microcosms tested with water chemistry kits and daytime RUSS data provide evidence for photosynthetic activity. Decreasing oxygen concentrations in student built microcosms with fish and nighttime RUSS data provide evidence of respiration. The net balance of photosynthesis and respiration plays a major role in determining the level of oxygen present in lakes, particularly at depth in lakes. Oxygen levels at different depths differ if a lake is thermally stratified. Furthermore, as a byproduct of their larger will generally illustrate changes in oxygen concentration more dramatically than lakes which are less rich in nutrients and biomass.
Students are challenged to demonstrate that photosynthesis and respiration occur in lakes. They begin by attempting to demonstrate that photosynthesis and respiration can be measured in lab microcosms. Students need to choose a water quality measure(s) to analyze in laboratory microcosms. They should begin by researching the effects that respiration can have on water temperature, pH, CO2, and DO, using the "Understanding" portion of the WOW website. They should choose a measure(s) that they feel correlates strongly to photosynthesis and . Students should write a procedural plan for testing their hypothesis.