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Date	November 2018	Marks available	1	Reference code	18N.2.HL.TZ0.1
Level	Higher level	Paper	Paper 2	Time zone	TZ0 / no time zone
Command term	State	Question number	1	Adapted from	N/A

Question

Mutagens can be removed from the body by converting them to readily excreted metabolites. NNK is converted to a metabolite, NNAL-Gluc, which can be used as a biomarker for the uptake of NNK. Cotinine, a metabolite of nicotine, is an indicator of tobacco smoke uptake. The graph shows the relationship between these two metabolites in the urine of 233 smokers.

State the highest concentration of cotinine in the urine, giving the units.

[1]

Deduce, with a reason, whether the concentrations of cotinine and NNAL-Gluc would be higher in the urine or in the blood plasma of a smoker.

[1]

d.i.

Suggest one advantage of using the urine concentration of cotinine rather than NNAL-Gluc to give a measure of the amount of tobacco smoke inhaled by a person.

[1]

d.ii.

Markscheme

42 nmol ml^–1 ✔

higher in urine due to concentration of waste products «during the process of urine production»
OR
higher in urine because water is reabsorbed «from glomerular filtrate/in the collecting duct»/ because «waste products» are not reabsorbed ✔

d.i.

higher «concentrations» so easier to measure/identify/find
OR
wider spread/greater range «of values/concentrations»
OR
units are larger/nmol rather than pmol ✔

d.ii.

Examiners report

[N/A]

d.i.

[N/A]

d.ii.

Syllabus sections

Additional higher level » Topic 8: Metabolism, cell respiration and photosynthesis » 8.1 Metabolism

Additional higher level » Topic 8: Metabolism, cell respiration and photosynthesis

Additional higher level

Question

Markscheme

Examiners report

Syllabus sections

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