Question 20N.3.SL.TZ0.18
| Date | November 2020 | Marks available | [Maximum mark: 6] | Reference code | 20N.3.SL.TZ0.18 |
| Level | SL | Paper | 3 | Time zone | TZ0 |
| Command term | Compare and contrast, Explain, Identify | Question number | 18 | Adapted from | N/A |
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]
Kupffer (cell);
Most candidates could identify the Kupffer cell (with a variety of spellings), and the hepatic portal vein.
Identify the blood vessel labelled Y which brings blood from the intestines.
[1]
(hepatic) portal vein/venule;
“Portal” alone is insufficient
Explain the function of hepatocytes in protein metabolism.
[2]
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;
The function of the hepatocytes in protein metabolism was challenging for most candidates despite this being taken directly from an assessment statement.
Compare and contrast the structure of sinusoids and capillaries.
[2]
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;
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.