Respiration in Plants Test - 30

The respiratory quotient (R.Q) is the ratio of $$CO_2$$ produced to $$O_2$$ consumed, while food is being metabolized.
RQ = $$CO_2$$ eliminated / $$O_2$$ consumed
R.Q for proteins is less than 1 since, amount of $$CO_2$$ evolved is lesser than amount of $$O_2$$ consumed.
When organic acids are broken down as respiratory substrates under aerobic conditions the R.Q is more than one. Organic acids contain more oxygen than carbohydrates and therefore require less oxygen for their oxidation.
R.Q is equal to zero for CAM plants at night time since, no $$CO_2$$ is evolved and $$O_2$$ is continuously consumed.
Thus, option D is correct.

The three processes are involved in the anaerobic respiratory process, glycolysis, Calvin cycle and electron transport chain. There are no steps where the oxygen molecule is released. The oxygen molecule is used for the breakdown through oxidation of the carbohydrate. There is release if the carbon dioxide molecule in this process.

The Krebs cycle (or citric acid cycle) is a part of cellular respiration. Direct formation of ATP in Krebs cycle occurs during the conversion of ketoglutarate to succinate, which is the intermediate reaction. 
Glucose-1-phosphate to glucose-6-phosphate conversion does not occur in Krebs cycle. Thus, option A is wrong.
Citrate to isocitrate conversion occurs in Krebs cycle but does not leads to formation of ATP. Thus, option B is wrong.
Isocitrate to cis-aconitate conversion does not occur in Krebs cycle but reverse reaction takes place and does not lead to production of ATP. 

The respiratory quotient (R.Q) is the ratio of $$CO_2$$ produced to $$O_2$$ consumed, while food is being metabolized.
RQ = $$CO_2$$ eliminated / $$O_2$$ consumed
R.Q for proteins is less than 1. Because, amount of $$O_2$$ consumed is higher than amount of $$CO_2$$ eliminated. So, protein rich pulses have R.Q less than 1. Thus, option C is correct and other options are incorrect.

Conversion of succinic acid to fumaric acid is the intermediate step in TCA cycle catalyzed by succinate dehydrogenase, which produce 1 $$FADH_2$$ molecule, that is equal to 2 ATP molecules. 

The form in which carbon leaves the citric acid cycle is carbon dioxide. CO$${_2}$$ gets released from the citric acid cycle in the conversion of isocitrate to ketoglutarate and ketoglutarate to succinate. 
Acetaldehyde, ethanol and lactate are not produced during the citric acid cycle. Thus, the correct answer is option D. 

Glycolysis or EMP pathway is the metabolic pathway, that converts glucose into pyruvate. The free energy released in this process is used to form the high-energy compounds ATP and NADPH. Glycolysis occurs in cytosol due to availability of enzymes. This pyruvate then enters into mitochondrial matrix for further process. Thus, option A is correct.
The enzymes of EMP are not located in mitochondria, lysosomes and ribosomes. Thus, other options are incorrect.

Solution:

Correct answer is option B.

Explanation for correct option:

• Kreb cycle is the second phase of aerobic respiration and starts with the condensation of acetyl CoA with OAA forms citrate, the first tricarboxylic acid of Kreb cycle. That's why it is also called as citric acid cycle and tricarboxylic acid cycle.
• Calvin cycle refers to the enzymatic reaction that fixes carbon dioxide into carbohydrates. Series of reactions that produce urea from ammonia are collectively termed the urea cycle. 

Kreb cycle produces 8 molecules of NADH plus 2 molecules of $$FADH_2$$ (via succinate dehydrogenase) in the mitochondrial matrix. During electron transport through the inner mitochondrial membrane, NADH and $$FADH_2$$ pump electrons through a series of electron transport proteins to final acceptor oxygen. This electron transport chain ensures availability of NAD and FAD for next round of Kreb cycle. Nonavailability of these reducing powers results in entry of pyruvate in anaerobic respiration pathway. So, to maintain continuity of Kreb cycle, oxidation of NADH and $$FADH_2$$ by oxygen is prerequisite and the cycle is considered aerobic. Thus, the correct answer is option D.

Pyruvate decarboxylation is a reaction that uses pyruvate to form acetyl-CoA, releasing NADH, a reducing equivalent, and carbon dioxide via decarboxylation. This reaction is very common in most organisms as a link between glycolysis and the citric acid cycle. In organisms that perform aerobic respiration, the reaction is usually catalyzed by the pyruvate dehydrogenase complex. The prosthetic groups involved in this reaction are TPP, co-enzyme A, lipoic acid and NAD. Mn does not act as a prosthetic group to the above reaction.