Test: Respiratory Substrates & Respiratory Quotient - NEET MCQ

Respiration is an oxidative process in which repiratory substrates are oxidised to liberate energy inside the living cells. The common respiratory substrates are carbohydrates, proteins, fats and organic acids. The most common respiratory substrates are carbohydrates, proteins, fats and organic acids. The most common respiratory substrate is glucose.

Topic in NCERT: Respiratory substrates

Line in NCERT: "the compounds that are oxidised during this process are known as respiratory substrates."

In anaerobic respiration, there is no consumption of oxygen and carbon dioxide is produced in most of the cases. Therefore, respiratory quotient is infinity. Carb the usual substarte.

Topic in NCERT: Respiratory quotient

Line in NCERT: "the ratio of the volume of co2 evolved to the volume of o2 consumed in respiration is called the respiratory quotient (rq) or respiratory ratio."

When facts are used in respiration, the RQ is less than 1, e.g. for the breakdown of tripalmitin,

Topic in NCERT: Respiratory quotient

Line in NCERT: "when carbohydrates are used as substrate and are completely oxidised, the rq will be 1, because equal amounts of co2 and o2 are evolved and consumed, respectively, as shown in the equation below :"

The correct option is 2 i.e., conversion of Succinyl coA to Succinic acid.
During the conversion of succinyl-CoA to succinic acid a molecule of GTP is synthesised. This is a substrate level phosphorylation.
The other 3 steps involve oxidation-reduction reaction where NAD+ is reduced to NADH + H⁺ and one point where FAD⁺ is reduced to FADH2.

Topic in NCERT: Citric acid cycle

Line in NCERT: "during the conversion of succinyl-coa to succinic acid a molecule of gtp is synthesised. this is a substrate level phosphorylation."

The correct answer is: (a) The type of respiratory substrate used

The Respiratory Quotient (RQ) is the ratio of the volume of carbon dioxide (CO₂) produced to the volume of oxygen (O₂) consumed during respiration. Its value depends primarily on the type of respiratory substrate being metabolized:

• Carbohydrates: RQ = 1 (equal amounts of O₂ consumed and CO₂ produced).
• Fats: RQ < 1 (more O₂ consumed than CO₂ produced).
• Proteins: RQ ≈ 0.8 (less O₂ consumed than CO₂ produced).

Other factors, such as location or ventilation, do not directly determine the RQ.

Topic in NCERT: Respiratory quotient

Line in NCERT: "the respiratory quotient depends upon the type of respiratory substrate used during respiration."