AP BIOLOGY

CELL RESPIRATION

AEROBIC RESPIRATION

Question [CLICK ON ANY CHOICE TO KNOW THE RIGHT ANSWER]
The respiratory quotient (RQ) is used to determine the type of respiratory substrate, such as carbohydrate or lipid, which an organism uses at any one time. State how the RQ is calculated.
A
volume x number of moles (of both gases)
B
Carbon dioxide produced multiply by oxygen consumed, volume/ number of moles (of both gases)
C
Carbon dioxide produced divided by oxygen consumed, volume/ number of moles (of both gases)
D
Carbon dioxide consumed divided by oxygen produce, volume/ number of moles (of both gases)
Explanation: 

Detailed explanation-1: -It happens to be measured using Ganong’s respirometer. When the carbohydrates are completely oxidized which are used as a substrate, the respiratory quotient becomes one. Here equal amounts of carbon dioxide and oxygen are evolved and consumed, respectively. The RQ for carbohydrates is approximately 1.

Detailed explanation-2: -How does Respiratory Quotient (R.Q.) indicate which type of substrate, i.e. carbohydrate, fat or protein is getting oxidized? R.Q. = A/B.

Detailed explanation-3: -The RQ formula is RQ = CO2 produced / O2 consumed, where the gases are given in the same units. To calculate the respiratory quotient from a metabolic equation, the number of CO2 molecules is divided by the number of O2 molecules. Generally, the RQ of: carbohydrates is about 1.0.

Detailed explanation-4: -The respiratory quotient value indicates which macronutrients are being metabolized, as different energy pathways are used for fats, carbohydrates, and proteins. If metabolism consists solely of lipids, the respiratory quotient is approximately 0.7, for proteins it is approximately 0.8, and for carbohydrates it is 1.0.

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