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CAIE A-Level Biology A2 12.1.6 Rq Calculations Questions

First obtain the carbon-dioxide and oxygen coefficients from the complete aerobic-respiration equation. Divide carbon dioxide produced by oxygen consumed, show the working and…

Syllabus
2028–2030
Course
Biology 9700
Level
A2

Exam points

  • Complete or balance a respiratory-substrate equation to obtain the carbon-dioxide and oxygen coefficients needed for an RQ calculation.
  • Calculate respiratory quotient as carbon dioxide produced divided by oxygen consumed, show the substitution and give the answer to the requested precision.
  • Compare RQ values calculated from substrate formulae and oxygen requirements to identify the highest and lowest respiratory quotients.

CAIE A-Level Biology A2 12.1.6 Rq Calculations Questions question 1

[Maximum number: 3]

Question (a)

(a)

The respiratory quotient, RQ, is used to show which substrate is being metabolised by cells. It can be determined using the equation below.

RQ= molecules of carbon dioxide released  molecules of oxygen taken in \mathrm{RQ}=\frac{\text { molecules of carbon dioxide released }}{\text { molecules of oxygen taken in }}

Lauric acid is a saturated fatty acid found in coconuts and has a chain of 12 carbon atoms.

[ 3 ]

Question (i)

(i)

Complete the equation below which outlines the aerobic respiration of lauric acid.

C12H24O2+……O2⟶12CO2+12H2O\mathrm{C}_{12} \mathrm{H}_{24} \mathrm{O}_{2}+\ldots \ldots \mathrm{O}_{2} \longrightarrow 12 \mathrm{CO}_{2}+12 \mathrm{H}_{2} \mathrm{O}
[ 1 ]

Question (ii)

(ii)

Calculate the RQ value for lauric acid.

Show your working. Give your answer to 2 decimal places.
answer =

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