Outline the role of the liver in the metabolism of fat (⅓ marks), carbohydrate (⅓ marks) and proteins (⅓ marks).
This question relates to basic hepatic physiology and is well described in the recommended texts. The mark allocation and division of time was indicated in the question. Better answers used the categorisation in the question as an answer structure. Many candidates gave a good description of beta oxidation, the formation of Acetyl Co A and ketone synthesis. A description of the synthesis of cholesterol, phospholipids, lipoproteins and fatty acid synthesis from proteins and carbohydrates mainly using glycogen, glucose and lactate also received marks. Candidates seem to have a better understanding of fat and glucose metabolism than protein metabolism. Higher scoring candidates appreciated the anabolic and catabolic processes of each component.
As a sterol, cholesterol probably does belong in the "fat" category, but the way the question reads might seem to suggest that mainly dietary macronutrients were being asked about. From seeing the stem and the breakdown of marks, a casual reader would not immediately understand that phospholipid synthesis or lactate metabolism would be an essential part of the answer. What follows is an attempt to answer the question as it was written (whereas the college comments describe the answer to a somewhat different question).
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Mitra, Vikramjit, and Jane Metcalf. "Metabolic functions of the liver." Anaesthesia & Intensive Care Medicine 10.7 (2009): 334-335.
Campbell, Iain. "Liver: metabolic functions." Anaesthesia & Intensive Care Medicine 7.2 (2006): 51-54.
Alamri, Zaenah Zuhair. "The role of liver in metabolism: an updated review with physiological emphasis." (2018) International Journal of Basic & Clinical Pharmacology, [S.l.], v. 7, n. 11, p. 2271-2276, oct. 2018. ISSN 2279-0780.
Adeva-Andany, María M., et al. "Liver glucose metabolism in humans." Bioscience reports 36.6 (2016).
Rui, Liangyou. "Energy metabolism in the liver." Comprehensive physiology 4.1 (2014): 177.
Huang, Jiansheng, Jayme Borensztajn, and Janardan K. Reddy. "Hepatic lipid metabolism." Molecular pathology of liver diseases. Springer, Boston, MA, 2011. 133-146.