Pearson Edexcel IAL Biology 7.6 Respiratory quotient

Practise respiratory quotient by calculating CO2 produced against O2 used and linking RQ values to fat or carbohydrate substrates.

Exam points

calculate RQ from carbon dioxide produced divided by oxygen used in tables or investigations
interpret a falling RQ as a shift towards lipid or fat use during respiration

[Maximum number: 1]

Animals use aerobic and anaerobic respiration to produce ATP.

Aerobic respiration has three stages where reactions occur between enzymes and substrates.

A student calculated the volume of oxygen used by a cockroach as $1.7 \mathrm{~cm}^{3}$ hour ${ }^{-1}$ . The same cockroach produced $1.3 \mathrm{~cm}^{3}$ hour ${ }^{-1}$ of carbon dioxide in the same time.

What is the respiratory quotient (RQ) of this cockroach?

0.7

0.8

1.3

2.2

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7.6—Respiratory quotient question 1