R.Q. Questions in English

(B) $Q_{10}$ is defined as the temperature coefficient.
It represents the factor by which the rate of a reaction or a biological process increases when the temperature is raised by $10^{\circ}C$.
Therefore,$Q_{10}$ stands for the temperature quotient.

(C) The Respiratory Quotient $(RQ)$ is defined as the ratio of the volume of $CO_2$ evolved to the volume of $O_2$ consumed during respiration.
When organic acids (such as oxalic acid or malic acid) are used as respiratory substrates,they are already rich in oxygen.
Therefore,the amount of $CO_2$ released during their oxidation is greater than the amount of $O_2$ consumed,resulting in an $RQ$ value greater than $1$ $(RQ > 1)$.

(A) The respiratory quotient $(R.Q.)$ is defined as the ratio of the volume of $CO_2$ evolved to the volume of $O_2$ consumed during respiration.
For glucose $(C_6H_{12}O_6)$, the aerobic respiration equation is:
$C_6H_{12}O_6 + 6O_2 \rightarrow 6CO_2 + 6H_2O + \text{Energy}$
Using the formula:
$R.Q. = \frac{\text{Volume of } CO_2 \text{ evolved}}{\text{Volume of } O_2 \text{ consumed}}$
$R.Q. = \frac{6}{6} = 1$
Therefore, the $R.Q.$ for glucose is $1$.

(A) The Respiratory Quotient $(R.Q.)$ is defined as the ratio of the volume of $CO_2$ evolved to the volume of $O_2$ consumed during respiration.
For carbohydrates,the $R.Q.$ is $1$. For fatty acids,the $R.Q.$ is typically less than $1$ (usually around $0.7$) because they are highly reduced and require more oxygen for oxidation.
However,among the options provided,none of the fatty acids (Oleic,Stearic,Palmitic) have an $R.Q.$ of $1$. Acetic acid is a simple organic acid that can be fully oxidized in the respiratory pathway,and in specific metabolic contexts,it can exhibit an $R.Q.$ of $1$ because its chemical structure $(CH_3COOH)$ allows for an equal ratio of $CO_2$ production to $O_2$ consumption $(CH_3COOH + 2O_2 \rightarrow 2CO_2 + 2H_2O)$.
Therefore,Acetic acid is the correct answer.

(D) The Respiratory Quotient $(R.Q.)$ is defined as the ratio of the volume of $CO_2$ evolved to the volume of $O_2$ consumed during respiration.
For carbohydrates, the $R.Q.$ value is $1.0$ because the number of $CO_2$ molecules released equals the number of $O_2$ molecules consumed in the oxidation of hexose sugars $(C_6H_{12}O_6 + 6O_2 \rightarrow 6CO_2 + 6H_2O + \text{Energy})$.
Green organs like the stems and leaves of wheat, barley, and oat primarily utilize carbohydrates as respiratory substrates.
Therefore, all the mentioned options exhibit a unit value of $R.Q.$

(A) The $R.Q.$ (Respiratory Quotient) is defined as the ratio of the volume of $CO_2$ evolved to the volume of $O_2$ consumed during respiration.
It depends directly on the chemical nature of the respiratory substrate being oxidized.
For example,the $R.Q.$ for carbohydrates is $1$,for fats it is less than $1$,and for proteins it is approximately $0.9$.
Therefore,knowing the value of $R.Q.$ helps in identifying the type of substrate being used in respiration.

(A) The $RQ$ (Respiratory Quotient) is defined as the ratio of the volume of $CO_2$ evolved to the volume of $O_2$ consumed during respiration.
Since different respiratory substrates (such as carbohydrates,fats,and proteins) have different chemical compositions,the amount of $O_2$ required for their oxidation and the amount of $CO_2$ released varies accordingly.
Therefore,the value of $RQ$ depends primarily on the chemical nature of the respiratory substrate being oxidized.

(B) The $RQ$ (Respiratory Quotient) is defined as the ratio of the volume of $CO_2$ evolved to the volume of $O_2$ consumed during respiration.
Maize seeds are rich in carbohydrates,which have an $RQ$ of approximately $1.0$.
Groundnut seeds are rich in fats (fatty acids),which have an $RQ$ of approximately $0.7$.
Since the mixture contains both carbohydrates and fats,the average $RQ$ of the mixture will be the weighted average of the two values.
Because the $RQ$ of fats is less than $1$,the overall $RQ$ of the mixture will be less than $1$.

(B) The Respiratory Quotient $(RQ)$ is defined as the ratio of the volume of $CO_2$ evolved to the volume of $O_2$ consumed.
In Ganong's respirometer:
$(i)$ The first rise of saline $(V_1)$ represents the volume of $O_2$ consumed = $10 \, ml$.
(ii) The second rise of saline after adding $KOH$ $(V_2)$ represents the volume of $CO_2$ evolved = $30 \, ml$.
Therefore,the total volume of $O_2$ consumed is the sum of the first rise and the volume of $CO_2$ (since $CO_2$ was absorbed by $KOH$ in the second step).
$RQ = \frac{\text{Volume of } CO_2}{\text{Volume of } O_2} = \frac{V_2}{V_1 + V_2} = \frac{30}{10 + 30} = \frac{30}{40} = 0.75$.

(D) At the compensation point,the rate of photosynthesis is equal to the rate of respiration.
Consequently,the net volume of $O_2$ absorbed from the atmosphere is zero,and the net volume of $CO_2$ evolved into the atmosphere is zero.
Since the Respiratory Quotient $(RQ)$ is defined as the ratio of the volume of $CO_2$ evolved to the volume of $O_2$ absorbed,at the compensation point,it becomes:
$RQ = \frac{\text{Vol. of } CO_2 \text{ evolved}}{\text{Vol. of } O_2 \text{ absorbed}} = \frac{0}{0} = 0$.

(A) $R.Q.$ stands for Respiratory Quotient.
It is defined as the ratio of the volume of carbon dioxide evolved to the volume of oxygen consumed during respiration.
Mathematically,$R.Q. = \frac{\text{Volume of } CO_2 \text{ evolved}}{\text{Volume of } O_2 \text{ consumed}}$.

(C) The $R.Q.$ is defined as the ratio of the volume of $CO_2$ evolved to the volume of $O_2$ consumed during respiration $(R.Q. = \frac{Volume \ of \ CO_2 \ evolved}{Volume \ of \ O_2 \ consumed})$.
In certain succulent plants (like $Opuntia$ or $Bryophyllum$),organic acids are formed during the night,and $CO_2$ is consumed rather than evolved. However,if no $CO_2$ is evolved at all,the numerator becomes zero.
Therefore,when the respiratory substrate is not oxidized to release $CO_2$,or in specific conditions where $CO_2$ evolution is zero,the $R.Q.$ value is zero.

(B) The $R.Q.$ (Respiratory Quotient) is defined as the ratio of the volume of $CO_2$ evolved to the volume of $O_2$ consumed during respiration.
It depends directly on the chemical nature of the respiratory substrate being oxidized.
For example,carbohydrates have an $R.Q.$ of $1.0$,while fats have an $R.Q.$ of less than $1.0$ (approx $0.7$).
Therefore,the correct answer is that it depends on the substrate being oxidized.

(B) The Respiratory Quotient $(R.Q.)$ is defined as the ratio of the volume of $CO_2$ evolved to the volume of $O_2$ consumed during respiration.
For fatty substances (fats),the $R.Q.$ is always less than $1$ (typically around $0.7$).
This is because fats are more reduced than carbohydrates and require more oxygen for their complete oxidation relative to the amount of $CO_2$ produced.

(B) The Respiratory Quotient $(RQ)$ is defined as the ratio of the volume of $CO_2$ evolved to the volume of $O_2$ consumed during respiration.
$RQ = \frac{\text{Volume of } CO_2 \text{ evolved}}{\text{Volume of } O_2 \text{ consumed}}$
When organic acids (like malic acid or oxalic acid) are used as respiratory substrates,the volume of $CO_2$ released is greater than the volume of $O_2$ consumed.
For example,in the case of malic acid,the $RQ$ is $1.33$,which is greater than $1$.
Therefore,the respiratory substance is an organic acid.

(D) In some succulent plants,such as $Opuntia$,carbohydrates are incompletely oxidized to organic acids during the night (dark) without the release of $CO_2$.
The chemical reaction is: $2C_6H_{12}O_6 + 3O_2 \rightarrow 3C_4H_6O_5 + 3H_2O$.
Since $CO_2$ is not evolved during this process,the Respiratory Quotient $(R.Q.)$ is calculated as:
$R.Q. = \frac{\text{Volume of } CO_2 \text{ evolved}}{\text{Volume of } O_2 \text{ consumed}} = \frac{0}{3} = 0$.

(C) The respiratory quotient $(RQ)$ is defined as the ratio of the volume of $CO_2$ evolved to the volume of $O_2$ consumed during respiration.
In succulent plants (like $Opuntia$ or $Bryophyllum$),organic acids are formed due to the incomplete oxidation of carbohydrates during the night (Crassulacean Acid Metabolism or $CAM$ pathway).
Because the oxidation of carbohydrates is incomplete,the amount of $CO_2$ released is significantly lower than the amount of $O_2$ consumed,resulting in an $RQ$ value of less than $1$.

(B) $R.Q.$ stands for Respiratory Quotient.
It is defined as the ratio of the volume of $CO_2$ evolved to the volume of $O_2$ consumed during respiration.
The formula is: $R.Q. = \frac{\text{Volume of } CO_2 \text{ evolved}}{\text{Volume of } O_2 \text{ consumed}}$.
Therefore,the correct representation is $\frac{CO_2}{O_2}$.

(C) The $R.Q.$ (Respiratory Quotient) is defined as the ratio of the volume of $CO_2$ evolved to the volume of $O_2$ consumed during respiration.
In germinating castor seeds,the primary respiratory substrate is fat (lipids).
Since fats are highly reduced compounds,they require more oxygen for complete oxidation compared to carbohydrates.
For fats,the $R.Q.$ is typically around $0.7$,which is less than one.

(C) The chemical equation for the aerobic respiration of maleic acid $(C_4H_4O_4)$ is:
$C_4H_4O_4 + 3O_2 \rightarrow 4CO_2 + 2H_2O$
The Respiratory Quotient $(R.Q.)$ is defined as the ratio of the volume of $CO_2$ evolved to the volume of $O_2$ consumed.
$R.Q. = \frac{\text{Volume of } CO_2 \text{ evolved}}{\text{Volume of } O_2 \text{ consumed}}$
$R.Q. = \frac{4}{3} = 1.33$
Therefore,the correct option is $C$.

(D) The Respiratory Quotient $(RQ)$ is defined as the ratio of the volume of $CO_2$ evolved to the volume of $O_2$ consumed during respiration.
For carbohydrates (like Glucose),the $RQ$ is $1.0$.
For fats,the $RQ$ is approximately $0.7$.
For organic acids,the $RQ$ is greater than $1.0$ (e.g.,for malic acid,it is $1.33$).
Therefore,the correct order is: $RQ$ of Fats $(0.7)$ < $RQ$ of Glucose $(1.0)$ < $RQ$ of Organic acid $(>1.0)$.
Thus,the correct relationship is $RQ$ of Fats < $RQ$ of Glucose < $RQ$ of Organic acid.

(D) The Respiratory Quotient $(R.Q.)$ is defined as the ratio of the volume of $CO_2$ evolved to the volume of $O_2$ consumed during respiration.
For carbohydrates like glucose and fructose,the $R.Q.$ is $1$.
For fats,the $R.Q.$ is less than $1$ (approximately $0.7$).
For organic acids,the $R.Q.$ is greater than $1$ because they are oxygen-rich compounds and require less atmospheric oxygen for their oxidation.

(A) The $R.Q.$ (Respiratory Quotient) is defined as the ratio of the volume of $CO_2$ evolved to the volume of $O_2$ consumed during respiration.
Sprouting potato tubers primarily utilize carbohydrates (starch) as their respiratory substrate.
For carbohydrates, the chemical equation for aerobic respiration is: $C_6H_{12}O_6 + 6O_2 \rightarrow 6CO_2 + 6H_2O + \text{Energy}$.
Thus, $R.Q. = \frac{\text{Volume of } CO_2 \text{ evolved}}{\text{Volume of } O_2 \text{ consumed}} = \frac{6}{6} = 1$.
Therefore, the $R.Q.$ of sprouting potato tubers is $1$.

(C) The Respiratory Quotient $(RQ)$ is a dimensionless ratio used in calculations of basal metabolic rate when estimated from carbon dioxide production and oxygen consumption.
It is defined as the ratio of the volume of $CO_2$ evolved to the volume of $O_2$ consumed during respiration.
The formula is: $RQ = \frac{\text{Volume of } CO_2 \text{ evolved}}{\text{Volume of } O_2 \text{ consumed}}$.

(A) The respiratory quotient $(RQ)$ is defined as the ratio of the volume of $CO_2$ evolved to the volume of $O_2$ consumed during respiration.
For carbohydrates, the chemical equation for aerobic respiration is: $C_6H_{12}O_6 + 6O_2 \rightarrow 6CO_2 + 6H_2O + \text{Energy}$.
Here, the volume of $CO_2$ evolved is $6$ and the volume of $O_2$ consumed is $6$.
Therefore, $RQ = \frac{6CO_2}{6O_2} = 1$.
Since the value is $1$, it is referred to as unity.

(B) During anaerobic respiration,oxygen $({O_2})$ is not consumed,while carbon dioxide $({CO_2})$ is produced as a byproduct.
The formula for Respiratory Quotient $(R.Q.)$ is: $R.Q. = \frac{\text{Volume of } CO_2 \text{ evolved}}{\text{Volume of } O_2 \text{ consumed}}$.
Since the volume of ${O_2}$ consumed is $0$,the value of $R.Q.$ becomes $\frac{\text{Volume of } CO_2}{0}$,which is mathematically defined as infinity $(\infty)$.

(D) The Respiratory Quotient $(RQ)$ is defined as the ratio of the volume of $CO_2$ evolved to the volume of $O_2$ consumed.
First,calculate the number of moles for each gas:
Moles of $CO_2 = \frac{\text{Given mass}}{\text{Molar mass}} = \frac{264 \ g}{44 \ g/mol} = 6 \ mol$.
Moles of $O_2 = \frac{\text{Given mass}}{\text{Molar mass}} = \frac{192 \ g}{32 \ g/mol} = 6 \ mol$.
Since the volume of a gas is directly proportional to the number of moles at constant temperature and pressure,the ratio of volumes is equal to the ratio of moles.
$RQ = \frac{\text{Volume of } CO_2}{\text{Volume of } O_2} = \frac{6 \ mol}{6 \ mol} = 1$.
Therefore,the value is unity.

(C) The respiratory quotient $(R.Q.)$ is defined as the ratio of the volume of $CO_2$ evolved to the volume of $O_2$ consumed during respiration.
For the given substrate $C_{39}H_{72}O_6$ (a fat/lipid),the balanced chemical equation for aerobic respiration is:
$2\ C_{39}H_{72}O_6 + 108\ O_2 \rightarrow 78\ CO_2 + 72\ H_2O$
Using the formula $R.Q. = \frac{\text{Volume of } CO_2 \text{ evolved}}{\text{Volume of } O_2 \text{ consumed}}$:
$R.Q. = \frac{78}{108} \approx 0.72$
Therefore,the correct option is $C$.

(B) The respiratory quotient $(RQ)$ is defined as the ratio of the volume of $CO_2$ evolved to the volume of $O_2$ consumed during the process of respiration.
The formula is given by:
$RQ = \frac{\text{Volume of } CO_2 \text{ evolved}}{\text{Volume of } O_2 \text{ consumed}}$
This value helps in determining the type of respiratory substrate being oxidized.

(A) The Respiratory Quotient $(R.Q.)$ is defined as the ratio of the volume of carbon dioxide $(CO_2)$ evolved to the volume of oxygen $(O_2)$ consumed during respiration.
Mathematically,it is expressed as: $R.Q. = \frac{\text{Volume of } CO_2 \text{ evolved}}{\text{Volume of } O_2 \text{ consumed}}$.
Therefore,the correct formula is $\frac{CO_2}{O_2}$.

(C) The $R.Q.$ (Respiratory Quotient) is defined as the ratio of the volume of $CO_2$ evolved to the volume of $O_2$ consumed during respiration.
$(c)$ The $R.Q.$ of organic acids is always more than one because they are oxygen-rich compounds.
For example, in the case of oxalic acid:
$2(COOH)_2 + O_2 \to 4CO_2 + 2H_2O$
$R.Q. = \frac{\text{Volume of } CO_2 \text{ evolved}}{\text{Volume of } O_2 \text{ consumed}} = \frac{4}{1} = 4$.
Since $4 > 1$, the $R.Q.$ is more than one.

(B) The Respiratory Quotient $(RQ)$ is defined as the ratio of the volume of $CO_2$ evolved to the volume of $O_2$ consumed during respiration.
For carbohydrates, the $RQ$ is equal to $1$.
For proteins and fats, the $RQ$ is less than $1$ (usually around $0.7$ to $0.9$).
For organic acids, the $RQ$ is greater than $1$.
Therefore, the correct answer is $Protein$.

(C) The $R.Q.$ (Respiratory Quotient) is defined as the ratio of the volume of $CO_2$ evolved to the volume of $O_2$ consumed during respiration.
For fats,the $R.Q.$ is always less than $1$.
Specifically,for tripalmitin (a common fat),the $R.Q.$ is approximately $0.7$.
Among the given options,$0.703$ is the most accurate value representing the respiratory quotient for human fat.

(B) The diabetic patient shows a low respiratory quotient $(R.Q.)$.
This occurs because,in diabetes,the body is unable to utilize carbohydrates effectively due to a lack of insulin.
Consequently,the body relies more on the oxidation of fats for energy production.
The $R.Q.$ for carbohydrates is $1.0$,while the $R.Q.$ for fats is approximately $0.7$.
Therefore,an increased reliance on fat metabolism leads to a lower overall $R.Q.$ value.

(B) The respiratory quotient $(R.Q.)$ is defined as the ratio of the volume of $CO_2$ evolved to the volume of $O_2$ consumed during respiration.
For carbohydrates,the $R.Q.$ is $1.0$.
For fats,the $R.Q.$ is approximately $0.7$ because the amount of $CO_2$ released is less than the amount of $O_2$ absorbed.
For organic acids,the $R.Q.$ is greater than $1.0$.
Therefore,the correct option is $B$.

(A) The Respiratory Quotient $(RQ)$ is defined as the ratio of the volume of $CO_2$ evolved to the volume of $O_2$ consumed during respiration.
For carbohydrates, the complete oxidation reaction is: $C_6H_{12}O_6 + 6O_2 \rightarrow 6CO_2 + 6H_2O + \text{Energy}$.
Here, the volume of $CO_2$ evolved is $6$ and the volume of $O_2$ consumed is $6$.
Therefore, $RQ = \frac{6}{6} = 1$.
Thus, the $RQ$ for carbohydrates is $1$.

(B) The Respiratory Quotient $(R.Q.)$ is defined as the ratio of the volume of $CO_2$ evolved to the volume of $O_2$ consumed during respiration.
Mathematically,it is expressed as: $R.Q. = \frac{\text{Volume of } CO_2 \text{ evolved}}{\text{Volume of } O_2 \text{ consumed}}$.

(A) The $R.Q.$ (Respiratory Quotient) is defined as the ratio of the volume of $CO_2$ evolved to the volume of $O_2$ consumed during respiration.
When a cell is starving,it has exhausted its carbohydrate reserves and begins to respire using proteins or other organic acids as respiratory substrates.
However,in a state of extreme starvation,the cell may stop consuming $O_2$ while still releasing $CO_2$ through anaerobic processes or decarboxylation,or the metabolic processes become highly irregular.
In many biological contexts,the $R.Q.$ of a starving cell is considered to be zero because the cell stops taking in oxygen while metabolic activities continue to produce $CO_2$ or because the respiratory substrate is completely depleted.

(D) The Respiratory Quotient $(RQ)$ is defined as the ratio of the volume of $CO_2$ evolved to the volume of $O_2$ consumed during respiration.
For carbohydrates like glucose,starch,and sucrose (sugarcane),the $RQ$ is equal to $1$ because the volume of $CO_2$ evolved equals the volume of $O_2$ consumed.
For fats and proteins,which are complex organic substances,the $RQ$ is always less than $1$ because they require more oxygen for oxidation than the amount of $CO_2$ produced.
Groundnut seeds are rich in fats (oils),therefore,during their respiration,the $RQ$ is less than $1$ (approximately $0.7$).

(C) The respiratory quotient $(RQ)$ is defined as the ratio of the volume of $CO_2$ evolved to the volume of $O_2$ consumed during respiration.
To measure this ratio,a device called a Respirometer is used.
$A$ Potometer is used to measure the rate of transpiration.
$B$ Auxanometer is used to measure the growth of plants.
$D$ Warburg's apparatus is a specialized instrument used for measuring gas exchange in small samples,but the standard instrument for general respiratory quotient measurement is the Respirometer.

(D) The Respiratory Quotient $(R.Q.)$ is defined as the ratio of the volume of $CO_2$ evolved to the volume of $O_2$ consumed during respiration.
For carbohydrates like glucose and fructose,the $R.Q.$ is equal to $1$.
For fats,the $R.Q.$ is less than $1$ (usually about $0.7$).
For organic acids,the $R.Q.$ is greater than $1$ because they are oxygen-rich compounds and require less external oxygen for their oxidation.
Therefore,the correct option is $D$.

(A) The Respiratory Quotient $(RQ)$ is defined as the ratio of the volume of $CO_2$ evolved to the volume of $O_2$ consumed during respiration.
For fatty seeds (seeds rich in fats/lipids),the process of respiration requires more oxygen for the oxidation of fatty acids compared to the amount of carbon dioxide produced.
Since fats are highly reduced,they require more $O_2$ for complete oxidation.
Therefore,the $RQ$ value for fats is typically around $0.7$,which is less than $1$ $(RQ < 1)$.

(B) The $R.Q.$ (Respiratory Quotient) is defined as the ratio of the volume of $CO_2$ evolved to the volume of $O_2$ consumed during respiration.
Groundnut and castor seeds are oilseeds,meaning they contain a high amount of fatty acids (lipids) as their storage material.
When fats are used as respiratory substrates,they require more oxygen for complete oxidation compared to carbohydrates because they are more reduced.
Since the volume of $O_2$ consumed is greater than the volume of $CO_2$ evolved,the $R.Q.$ value for fats is always less than $1$ (typically around $0.7$).
Therefore,the correct option is $B$.

(A) The Respiratory Quotient $(R.Q.)$ is defined as the ratio of the volume of $CO_2$ evolved to the volume of $O_2$ consumed during respiration.
$R.Q. = \frac{\text{Volume of } CO_2 \text{ evolved}}{\text{Volume of } O_2 \text{ consumed}}$
Since the chemical composition of the respiratory substrate (such as carbohydrates,fats,or proteins) determines the amount of $O_2$ required for oxidation and the amount of $CO_2$ released,the nature of the respiratory substrate is the primary factor that induces a change in the $R.Q.$ value.

(D) The Respiratory Quotient $(RQ)$ is defined as the ratio of the volume of $CO_2$ evolved to the volume of $O_2$ consumed during respiration.
$RQ = \frac{\text{Volume of } CO_2 \text{ evolved}}{\text{Volume of } O_2 \text{ consumed}}$
For carbohydrates like glucose or sucrose,the $RQ$ is $1.0$.
For fats,the $RQ$ is less than $1.0$ (approximately $0.7$).
For organic acids (e.g.,malic acid or oxalic acid),the $RQ$ is greater than $1.0$ because they are oxygen-rich compounds,meaning they require less external $O_2$ for oxidation and release more $CO_2$ during the process.

(B) The Respiratory Quotient $(RQ)$ is defined as the ratio of the volume of $CO_2$ evolved to the volume of $O_2$ consumed during respiration.
For carbohydrates,the $RQ$ is $1$.
For fats (fatty acids),the $RQ$ is usually less than $1$ (approximately $0.7$).
For organic acids,the $RQ$ is greater than $1$.
Since sugars are carbohydrates,their $RQ$ is $1$.
Therefore,fats have an $RQ$ of less than $1$.

(D) The Respiratory Quotient $(RQ)$ is defined as the ratio of the volume of $CO_2$ evolved to the volume of $O_2$ consumed during respiration.
In actively photosynthesizing tissues,the $CO_2$ produced during respiration is immediately utilized for photosynthesis within the same tissue.
Consequently,the net amount of $CO_2$ released into the external environment is negligible or zero.
Therefore,the $RQ$ value for actively photosynthesizing tissue is considered to be $0$.

(D) The $R.Q.$ (Respiratory Quotient) is the ratio of the volume of $CO_2$ evolved to the volume of $O_2$ consumed.
In succulent plants (e.g.,$Opuntia$),organic acids (like malic acid) are formed during the night,which involves the incomplete oxidation of carbohydrates.
In this process,$CO_2$ is not evolved,but $O_2$ is consumed,resulting in an $R.Q.$ value of less than $1$ (approaching zero).
Therefore,the correct answer is $D$.

(B) The Respiratory Quotient $(RQ)$ is defined as the ratio of the volume of $CO_2$ evolved to the volume of $O_2$ consumed during respiration.
$RQ = \frac{\text{Volume of } CO_2 \text{ evolved}}{\text{Volume of } O_2 \text{ consumed}}$
For carbohydrates like glucose, the $RQ$ is $1.0$.
For fatty acids, the $RQ$ is less than $1.0$ (usually about $0.7$).
For organic acids (e.g., malic acid, oxalic acid), the $RQ$ is greater than $1.0$ because they are oxygen-rich and require less external $O_2$ for complete oxidation.
Therefore, when the volume of $CO_2$ evolved is more than the volume of $O_2$ consumed, the respiratory substrate is an organic acid.

(B) Ganong's respirometer is a specialized laboratory apparatus designed to measure the respiratory quotient $(RQ)$ of plant tissues.
$RQ$ is defined as the ratio of the volume of $CO_2$ evolved to the volume of $O_2$ consumed during respiration.
By measuring the changes in gas volumes within the apparatus,one can determine the $RQ$ value,which helps in identifying the type of respiratory substrate being oxidized.