The procedure used in this experiment could not be used to determine anaerobic respiration either. In anaerobic respiration, there is no electron transport chain and no Kreb's cycle by which the transport of raw electrons can be interrupted by DPIP. The DPIP could not take the place of ubiquinone and "steal" electrons away from NADH2. Pyruvate is converted to lactate and ethanol via NADH, not NADH2 so there would be no way to block the transport of electrons. Sodium azide might not be the correct chemical to block the transport of electrons to NADH. In this case, DPIP would not be able to measure the level of enzyme activity in the Kreb's cycle if there was no Kreb's cycle and no NADH2 to block using the sodium azide. The absorbance levels of the DPIP would not change considerably using the spectrophotometer, and perhaps they would even remain the same. This procedure then, would not be a good way to measure anaerobic respiration.
The process of cellular respiration is an important one and can be measured using simple techniques utilizing the source of all cellular respiration in organisms: the mitochondria. This is one of the single most important processes that occur within and organisms' cells.
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