Question

Study carefully the following statements and select the incorrect ones.
(i) When fats are used in respiration, the RQ is more than unity because fats contain more and require relatively less amount of oxidation.
(ii) The most important energy carrier is ATP. This energy-rich compound is mobile and can pass from one cell to another.
(iii) Before pyruvic acid enters Krebs' cycle, one of the two carbon atoms of pyruvic acid is reduced to carbon dioxide in the reaction called reductive carboxylation.
(iv) A special electron carrier system located in the mitochondrial membrane is called a shuttle system. It transfers electrons from the hydrogen of cytoplasmic NADH to the mitochondrial electron carriers across the mitochondrial membrane.
(v) Zymase is a complex mixture of many enzymes which requires several coenzymes for its action. The enzyme complex-zymase catalyzes a series of reactions taking place during fermentation leading to the production of ethyl alcohol.
A. (i) and (ii)
B. (iii) and (iv)
C. (i), (ii) and (iii)
D. (iii),(iv) and (v)

Answer 1

Respiratory quotient for fat oxidation is usually less than one. ATP is the energy currency and can provide energy wherever required.

Complete answer: RQ is usually less than one when fats are used as respiratory substrates. Fats are hydrolyzed into glycerol and fatty acids during respiration. Complete glycerol oxidation leads to an RQ of 0.86. For complete oxidation, the fatty acids, being poorer in oxygen, need more oxygen. The most relevant energy carrier is ATP (Adenosine triphosphate).
ATP or adenosine triphosphate transfers chemical energy anywhere within the cell wherever the energy-requiring mechanism goes on. But ATP molecules do not move from one cell to another.
Glycolysis-generated pyruvic acid enters the mitochondrial matrix and one of the three pyruvic acid’s carbon atoms undergoes oxidative decarboxylation before entering the citric acid cycle (Kreb’s cycle).

So, the correct answer is “Option C”.

Note: The respiratory quotient (RQ) is a dimensionless number used in BMR calculations.
RQ can be determined from the ratio of produced carbon dioxide to consumed oxygen. Using a respirometer, RQ can be measured.