Question

RQ of proteins, carbohydrates, fats, and organic acids are in the order
A. $ < 1,1, < 1, > 1$
B. $ > 1, < 1,1,1$
C. $1,1,0, - 1$
D. $0, < 1,1, > 1$

Answer 1

Hint: RQ is known as Respiratory Quotient which is used to determine the nature of the substrate which is respired during the process of respiration by a particular tissue.

Complete answer:
The respiratory quotient is the ratio of the volume of the carbon dioxide gas which is released to the volume of oxygen taken in during the process of respiration. It is measured at a specific time, per unit weight, and at a standard temperature and pressure.

The value of RQ varies based on the substrate and their oxidation.
RQ \[ = \dfrac{{C{O_2}{\text{ eliminated}}}}{{{O_2}{\text{ consumed}}}}\]

RQ for carbohydrates-
During aerobic respiration, six molecules of glucose and six molecules of oxygen react to form six molecules of carbon dioxide and six molecules of water.
Therefore, the RQ is $\dfrac{{6C{O_2}}}{{6{O_2}}} = 1$
During anaerobic respiration, one molecule of glucose gives rise to two molecules of ethanol and two molecules of carbon dioxide.
Therefore, the RQ is $\dfrac{{C{O_2}}}{{0{O_2}}} = $ infinity.
Therefore, for carbohydrates, it is equal to $1$

RQ of fats-
The RQ of triolein and tripalmitin is $0.71$ and $0.7$
Therefore, for fats, it is less than $1$

RQ of proteins is $0.9$
Therefore, for proteins, it is less than $1$

RQ is organic acids-
For organic acid like malic acid, RQ is $1.3$
Therefore, for organic acids, it is always more than $1$
So the RQ of proteins, carbohydrates, fats, and organic acids is $ < 1,1 < 1, > 1$

Hence, the correct answer is option (A).

Note: It must be kept in mind that the respiratory coefficients differ in organisms due to differences in metabolism. It ranges between the values of pure carbohydrate to the value of pure fat, that is $1 - 0.7$
Molecules that are more oxidized like glucose get metabolized easily and have a higher RQ.
Less oxidized molecules require more time for metabolism and hence, the RQ is also less.
Insulin is known to increase lipid storage and decreased fat oxidation and is thought to cause a positive increase in respiratory quotient.