Question

A respiratory substrate with formula ${C_{51}}{H_{98}}{O_6}$ is completely oxidized during respiration. What would be the ratio of the volume of $C{O_2}$ evolved to the volume of ${O_2}$ consumed in respiration?
A. More than one
B. Zero of infinite
C. Equal to one
D. Less than one

Answer 1

Aerobic respiration is the method by which most living organisms efficiently use food energy. This aerobic respiration consumes oxygen while releasing carbon dioxide. The respiratory quotient is the actual ratio of the volume of carbon dioxide expelled to the volume of oxygen consumed during cellular respiration.

Complete answer:
Option A: The Respiration Quotient is the ratio that occurs during the oxidation of organic molecules at constant temperature and pressure between the volume of carbon dioxide exhaled and the volume of oxygen taken in. Tripalmitin has the chemical formula ${C_{51}}{H_{98}}{O_6}$. $145{O_2}$ molecules are used in the oxidation of Tripalmitin, and $102C{O_2}$ molecules are released. The Respiratory Quotient is $0.7$, which is a satisfactory result.
Hence option A is not correct.
Option B: The Respiration Quotient is the ratio between the volume of carbon dioxide exhaled and the volume of oxygen taken in during the oxidation of organic molecules at constant temperature and pressure. ${C_{51}}{H_{98}}{O_6}$ is the chemical formula for tripalmitin. Tripalmitin is oxidized with $145{O_2}$ molecules, and $102C{O_2}$ molecules are liberated.
Hence this is an incorrect option.
Option C: The RQ is roughly $0.7$ when the respiratory substrate is fat (Tripalmitin). The RQ is $1$ when the respiratory substrate is a carbohydrate. The RQ is greater than $1$ when the respiratory substrate is an organic acid.
So, option C is not correct.
Option D: The Respiration Quotient is the ratio that occurs between the volume of carbon dioxide emitted and the volume of oxygen taken in during the oxidation of organic substances under constant temperature and pressure. Tripalmitin has the chemical formula ${C_{51}}{H_{98}}{O_6}$. $145{O_2}$ molecules are used and $102C{O_2}$ molecules are emitted during the oxidation of Tripalmitin. The Respiratory Quotient is $0.7$, which is below one.
Hence option D is correct.

Hence, Option D. is the correct answer.

Note:
Practical uses of the respiratory quotient can be recognized in extreme cases of chronic obstructive pulmonary disease, in which patients consume a significant amount of energy on respiratory exertion. By increasing the percentage of fats in the diet, the respiratory quotient is lowered, resulting in a reduction in the amount of $C{O_2}$ emitted. This reduces the amount of energy expended on breathing by lowering the $C{O_2}$ elimination respiratory pressure.