Question

In Opuntia R.Q is

• A. One
• B. Less than one
• C. More than one
• D. Zero

Answer 1

The correct option is D Zero

Respiratory Quotient (R.Q.) is the ratio of the volume of carbon dioxide evolved to the volume of oxygen absorbed during respiration by an organism in a given time. It is used to calculate the BMR (Basic metabolic rate) of an organism. The values of R.Q. are either one, zero, more than 1 or less than one. During aerobic respiration, R.Q. is less than 1 when respiratory substrate is protein or fat. During anaerobic respiration, R.Q. is more than 1 when carbohydrate is respiratory substrate. When respiration is aerobic, R.Q. is 1 if respiratory substrate is carbohydrate. When incomplete oxidation of respiratory substrate, carbohydrates takes place, R.Q. is zero. It is generally seen in succulent plants like opuntia. In this, respiration of carbohydrates occurs at night when stomata are open. This results in production of organic acids which utilize oxygen but do not evolve carbon dioxide.

Thus, the correct answer is option D.