Question 19M.3.SL.TZ2.17
| Date | May 2019 | Marks available | [Maximum mark: 5] | Reference code | 19M.3.SL.TZ2.17 |
| Level | SL | Paper | 3 | Time zone | TZ2 |
| Command term | Compare and contrast, List, State | Question number | 17 | Adapted from | N/A |
The diagram shows metabolic pathways for lactate in humans.
[Source: © International Baccalaureate Organization 2019]
State the name of the blood vessel through which lactate from muscles reaches the liver
[1]
hepatic artery ✔
The data showed possible metabolic pathways for lactate in humans. In (a) many candidates wrongly answered the hepatic portal vein.
Compare and contrast the possible metabolic pathways for lactate in hepatocytes and in mitochondria-rich tissue.
[2]
a. both produce pyruvate «from lactate»
OR
both produce CO2 and H2O «via acetyl CoA» ✔
b. hepatocytes produce glucose from lactate but mitochondria-rich cells cannot ✔
OWTTE – eg: “only hepatocytes produce glucose” would be acceptable.
Part (b) and (c) were well answered, the main error was confusing the hepatocytes with the Kupffer cells.
List two functions of hepatocytes other than regulating lactate levels in the blood.
1.
2.
[2]
a. detoxification ✔
b. production/secretion of bile ✔
c. conversion of cholesterol to bile salts ✔
d. production of plasma proteins ✔
e. nutrient storage ✔
f. glucose regulation «in blood» ✔
g. other function «eg deamination/transamination, conversion of ammonia to urea» ✔
Only two functions are required.
If more than two functions are given, mark only the first two listed.
Part (b) and (c) were well answered, the main error was confusing the hepatocytes with the Kupffer cells.