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Date November 2020 Marks available 2 Reference code 20N.3.SL.TZ0.18
Level Standard level Paper Paper 3 Time zone TZ0 / no time zone
Command term Compare and contrast Question number 18 Adapted from N/A

Question

The micrograph shows a section through part of the liver. The diagram illustrates the details of what is found within the marked area.

[micrograph] Micrograph of liver. https://undergraduate.vetmed.wsu.edu/courses/vph-308/histology/lab-1-histologycells-
and-organelles/liver-slide-wsu_2_052 courtesy of Patrick D. Wilson, MS, DVM, Clinical Associate Professor,
Veterinary Integrative Biosciences, College of Veterinary Medicine & Biosciences, Texas A&M University.

[diagram] Reprinted by permission from Springer Nature, Nature Reviews Immunology, “Aberrant homing of mucosal
T cells and extra-intestinal manifestations of inflammatory bowel disease” by Adams and Eksteen ©2006. https://www.nature.com/nri/

Identify the phagocyte labelled X.

[1]
a.i.

Identify the blood vessel labelled Y which brings blood from the intestines.

[1]
a.ii.

Explain the function of hepatocytes in protein metabolism.

[2]
b.

Compare and contrast the structure of sinusoids and capillaries.

[2]
c.

Markscheme

Kupffer (cell);

a.i.

(hepatic) portal vein/venule;

“Portal” alone is insufficient

a.ii.

a. they produce/secrete plasma proteins;

b. (the plasma proteins) are modified/secreted by the Golgi apparatus;

c. protein/globin is broken down into amino acids;

b.

a. both have walls 1 cell thick/same thickness
OR
both have a basement membrane;

b. sinusoids have pores/holes/fenestrations
OR
sinusoids have a wider lumen;

c.

Examiners report

Most candidates could identify the Kupffer cell (with a variety of spellings), and the hepatic portal vein.

a.i.
[N/A]
a.ii.

The function of the hepatocytes in protein metabolism was challenging for most candidates despite this being taken directly from an assessment statement.

b.

Comparison of sinusoids and capillaries produced many vague answers. Many candidates failed to treat the question as a ‘compare and contrast’ question which requires giving similarities and differences. Common errors included referring to blood type carried, cell membrane thickness and the position of the vessels in the body.

c.

Syllabus sections

Option D: Human physiology » Option D: Human physiology (Core topics) » D.3 Functions of the liver
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Option D: Human physiology » Option D: Human physiology (Core topics)
Option D: Human physiology

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