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Question 20N.3.HL.TZ0.b

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Date November 2020 Marks available [Maximum mark: 2] Reference code 20N.3.HL.TZ0.b
Level HL Paper 3 Time zone TZ0
Command term State Question number b Adapted from N/A
b.
[Maximum mark: 2]
20N.3.HL.TZ0.b

The graph shows the Bohr shift.

[Source: From The New England Journal of Medicine, Connie C.W. Hsia, Respiratory Function of
Hemoglobin, Volume 338(4):239–47. Copyright © 1998, Massachusetts Medical Society. Reprinted with permission
from Massachusetts Medical Society.]

State two modes of transport of carbon dioxide in blood. 

1.

2. 

[2]

Markscheme

a. dissolved/carried in plasma;

b. forms carbonic acid/H2CO3 (in plasma)
OR
as hydrogencarbonate (HCO3-) ions (in plasma);

c. binds to hemoglobin in red blood cells;

Examiners report

The majority of candidates did well also for this question, although some answers lacked accuracy.

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