Question

Respiratory quotient is

• A. More than one for organic acids.
• B. Less than one for proteins.
• C. Equal to zero for CAM plants at night.
• D. All of the above.

Answer 1

The correct option is D All of the above.

The respiratory quotient (R.Q) is the ratio of $C{O}_2$ produced to $O_2$ consumed, while food is being metabolized.
RQ = $C{O}_2$ eliminated / $O_2$ consumed
R.Q for proteins is less than 1 since, amount of $C{O}_2$ 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 $C{O}_2$ is evolved and $O_2$ is continuously consumed.
Thus, option D is correct.