Question

Value of RQ in succulents is?

• A. Unity
• B. Infinite
• C. Less than unity
• D. Zero

Answer 1

The correct option is D Zero

Where incomplete oxidation of carbohydrates takes place RQ is zero. In such cases, oxygen absorbed does not oxidize the carbohydrates completely to CO2 and water but produces intermediate products of partial oxidation. This occurs especially in respiration of succulent plants, such as cacti (Opuntia). In such plants respiration of carbohydrates occurs at night when stomata are open which results in the production of organic acids that utilize O2 but do not evolve CO2.

The equation is as follows:

2C${}_6$H${}_{1}2$O${}_2$ + 3O${}_2$ $\to$ 3C${}_4$H${}_6$O${}_5$ (malic acid) + 3H${}_2$O

The RQ = CO${}_2$/O${}_2$ = 0/3 = 0

So the correct option is 'zero'.