Final answer:
Stress-induced hyperventilation in metabolic rate experiments with roaches can cause an increase in the respiratory quotient (RQ) by artificially elevating the volume of CO2 produced, potentially misrepresenting the preferred metabolic substrate as more carbohydrate oxidation.
Step-by-step explanation:
If a student's metabolic rate experiment with roaches finds that they are stressed, hyperventilating, and exhaling more CO2 than at rest, the effect on the respiratory quotient (RQ) would be an increase. The RQ is defined as the ratio of the volume of carbon dioxide (CO2) produced to the volume of oxygen consumed. An increased rate of hyperventilation, where there is an increased ventilation rate leading to abnormally low blood carbon dioxide levels and high blood pH, would artificially increase the RQ value. This is because the CO2 production is being measured higher than it would be under normal resting conditions. Normally, the RQ varies depending on the substrate being metabolized, with fat and protein having an average RQ of about 0.7 and 0.8 respectively, and carbohydrates close to 1. Thus, stress-induced hyperventilation could lead to a misrepresentation of the preferred metabolic substrate, making it appear that more carbohydrate oxidation is occurring than actually is.