| Date | November 2017 | Marks available | 2 | Reference code | 17N.3.SL.TZ0.18 |
| Level | Standard level | Paper | Paper 3 | Time zone | TZ0 |
| Command term | Distinguish | Question number | 18 | Adapted from | N/A |
Question
The diagram shows the liver. The arrows show the direction of blood flow into and out of the liver.
[Source: © International Baccalaureate Organization 2017]
Identify the blood vessel labelled B.
Outline the function of the blood vessel labelled B.
Distinguish between the structure of liver sinusoids and capillaries.
Markscheme
«hepatic» portal vein
a. takes blood from intestine/spleen/pancreas/stomach to liver
b. carries digested food/nutrients/glucose
c. prevents glucose entering the general circulation
d. helps maintain osmotic potential of blood
e. allows toxins to be removed
[Max 3 Marks]
a. sinusoids have open pores/fenestrations/discontinuous endothelium and capillary endothelium is continuous/does not contain fenestrations
b. Kupffer cells are located inside sinusoids but not in capillaries
c. sinusoids larger in diameter than capillaries
Accept labelled diagrams
[Max 2 Marks]
| Date | May 2017 | Marks available | 1 | Reference code | 17M.3.SL.TZ2.20 |
| Level | Standard level | Paper | Paper 3 | Time zone | Time zone 2 |
| Command term | Outline | Question number | 20 | Adapted from | N/A |
Question
Rats were injected with antibodies that induced phagocytosis of red blood cells (erythrocytes) leading to their breakdown. The graph shows the percentage of intact and partially digested erythrocytes in cells of the liver as observed under the microscope.
State the name of the cells that perform the breakdown of erythrocytes in the liver.
Describe the breakdown of erythrocytes by liver cells.
Outline the fate of the iron from the erythrocytes.
Markscheme
Kupffer
a. cells phagocytose/engulf the erythrocytes
b. hemoglobin is split into heme group and globins
OR
heme is removed from hemoglobin
c. globins broken down/hydrolyzed to peptides/amino acids
d. heme group separated into iron and bilirubin
a. carried to bone marrow
b. used in the production of hemoglobin/new erythrocytes
| Date | May 2017 | Marks available | 2 | Reference code | 17M.3.SL.TZ1.19 |
| Level | Standard level | Paper | Paper 3 | Time zone | Time zone 1 |
| Command term | Suggest | Question number | 19 | Adapted from | N/A |
Question
The diagram below shows the liver and main vessels associated with it.
Suggest advantages of the blood supply from the pancreas passing directly into the liver.
Markscheme
a. the liver can respond quickly to hormones made by the pancreas
b. the pancreas secretes insulin / glucagon into the blood «traveling directly to the liver»
c. «the hormones released by the pancreas» stimulate the liver to store / release glucose
d. allows rapid regulation of blood glucose levels
| Date | November 2016 | Marks available | 4 | Reference code | 16N.3.SL.TZ0.18 |
| Level | Standard level | Paper | Paper 3 | Time zone | TZ0 |
| Command term | Explain | Question number | 18 | Adapted from | N/A |
Question
The micrograph shows a section through the human liver.
The cell labelled X is only found in the liver and is associated with the wall of a sinusoid.
(i) Identify cell X.
(ii) Outline the function of cell X.
Explain the importance of bilirubin in the onset of jaundice.
Markscheme
(i) Kupffer cell
(ii)
a. they are macrophages/phagocytes
b. break down red blood cells
c. separates heme (group) from (protein) globin chain
There is no ECF here.
a. «jaundice is» a yellowish pigmentation of the skin/whites of eyes
b. caused by high levels of bilirubin in blood/tissues
Simply stating “caused by high levels of bilirubin” is not enough for marking point b. However “tissues” may be implied as part of the answer to marking point a.
c. comes from breakdown of red blood cells
d. results from the breakdown of the heme group of hemoglobin
e. released into blood when excess is produced
f. released into blood when bile ducts blocked
g. normally excreted with bile
h. jaundice is often seen in liver disease such as hepatitis/liver cancer/chronic alcoholism/cirrhosis
OR
newborn/neonatal jaundice «due to immature liver»
| Date | May 2016 | Marks available | 2 | Reference code | 16M.3.SL.TZ0.19 |
| Level | Standard level | Paper | Paper 3 | Time zone | TZ0 |
| Command term | Outline | Question number | 19 | Adapted from | N/A |
Question
The liver’s unique blood supply and system of ducts allow proper functioning of its hepatocytes and Kupffer cells. These cells are found throughout the liver in functional units called liver lobules. The image shows a cross section of the blood and bile paths in a liver lobule.
Label the structures I, II, III and IV.
Outline functions of hepatocytes that involve changing the chemical composition of the plasma.
Markscheme
I: Portal venule (Do not accept portal vein in place of venule)
II: Kupffer cell
III: «Hepatic» sinusoid
IV: Hepatocyte/hepatic cell
Award [1] for any two correctly labelled.
Can store or release glucose
OR
regulate nutrient levels
Can remove toxins from/detoxify blood
Produce plasma proteins
Synthesis of cholesterol/phospholipids/bile salts
(Do not accept functions of Kupffer cells (eg: breaking down red blood cells))