Sun21November0437PM 16

A 24-year-old man participates in a trial investigating the effects of dietary substrates on metabolism. He is fed on granulated sugar and drinks water for two days.

Which of the following values best approximates to his expected respiratory quotient at the end of the trial?

(Please select 1 option)

0.9

0.67

0.7

1.0 Correct

1.1

Explanation

The respiratory quotient (RQ) is the ratio of CO2 produced by the body to the volume of O2 consumed per unit time:

RQ = CO2 produced / O2 consumed.

Typically 200 mL/minute CO2 produced and 250 mL/minute O2 consumed.

A mixed diet will typically produce and RQ of about 0.8.

The RQ will vary with the energy substrates in the diet.

Granulated sugar is a pure refined carbohydrate and is 99.999% carbohydrate with no significant lipid, proteins, minerals or vitamin content.

Glucose and other hexose sugars:

RQ = 1

Fats:

RQ = 0.7. Lipids require more oxygen than carbohydrates for complete oxidation.

Proteins:

RQ is approximately 0.9.

Ethyl alcohol:

RQ = 0.67

An RQ can exceed 1.0 when carbohydrate is converted into fat. In these circumstances there is likely to be fat deposition and gain of weight.

Answer Statistics

1

14%

2

10%

3

12%

4

62%

5

4%

Times answered: 252