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Question 18N.3.hl.TZ0.11b

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Date November 2018 Marks available [Maximum mark: 2] Reference code 18N.3.hl.TZ0.11b
Level hl Paper 3 Time zone TZ0
Command term Explain Question number b Adapted from N/A
b.
[Maximum mark: 2]
18N.3.hl.TZ0.11b

The transport of oxygen around the body is essential for life.

(b)

Explain why carbon monoxide is very toxic and how it may be possible to treat carbon monoxide poisoning.

[2]

Markscheme

Toxicity:

carboxyhemoglobin/Hb–CO does not readily dissociate

OR

CO + Hb ⇌ Hb–CO AND forward reaction favoured

OR

affinity of carbon monoxide/CO for hemoglobin is «200 times/much» higher than that of oxygen/O2

OR

competitive inhibitor of oxygen/O2 binding ✔

 

Treatment:

moving patient to fresh air

OR

«in severe cases» inhaling pure oxygen/O2

OR

high pressure oxygen/O2 chamber ✔

 

Accept “move away from carbon monoxide/CO source” OR “remove carbon monoxide/CO source”.

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