DP Biology (first assessment 2025)

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Question 19N.2.HL.TZ0.a

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Date November 2019 Marks available [Maximum mark: 4] Reference code 19N.2.HL.TZ0.a
Level HL Paper 2 Time zone TZ0
Command term Outline Question number a Adapted from N/A
a.
[Maximum mark: 4]
19N.2.HL.TZ0.a

Outline the reasons for the differences in blood concentrations between the renal artery and the renal vein.

[4]

Markscheme

a. urea/waste products lower in vein due to excretion «in urine»/ultrafiltration but not reabsorption ✔

b. oxygen lower in vein due to use in cell respiration/in kidney tissue ✔

c. carbon dioxide higher in vein due to production by cell respiration/excretion by kidney cells ✔

d. glucose lower in vein due to use in cell respiration «by kidney tissue» ✔

e. sodium/chloride/ion concentrations changed due to production of hypertonic/hypotonic urine
OR
sodium/chloride/ion concentrations lower due to removal of excess ✔

f. ion/solute concentrations lower in vein than artery if ADH has been secreted
OR
ion/solute concentrations in vein vary depending on amount of water reabsorbed in the collecting duct ✔

g. drug/toxin concentrations lower in vein due to excretion in urine ✔

Accept any point given as the converse.

Each mark point includes a difference and reason for it.

Syllabus sections