Explain how the liver stores and regulates levels of nutrients in the body, including details of the circulation of blood through the liver in your answer. You may use a diagram to illustrate your answer.

(circulation of blood through liver tissues – accept properly annotated diagram)
hepatic artery brings oxygenated blood;
hepatic portal vein brings nutrients (from small intestine);
merge to form sinusoids where liver cells/hepatocytes store and regulate nutrients;
blood leaves through hepatic vein;

(storage and regulation of nutrients)

one named stored nutrient; (e.g. carbohydrates/glycogen / iron / vitamin A/retinol / vitamin D/calciferol)
(award [1 max] for naming nutrients)

hepatocytes regulate blood sugar level by storing glucose as glycogen / releasing glucose from breakdown of glycogen (facilitated by arrival from portal vein);
under influence of insulin/glucagon (respectively) (carried by hepatic artery);
blood lipids/cholesterol synthesized/broken down if required / secreted through bile;
iron stored from breakdown of hemoglobin/released when Po₂ is low;

The majority of candidates scored high marks for this question and many covered a sufficient number of elements to gain all the marks despite too vague or incorrect statements in some of their answers. Candidates overall had a good understanding of the blood vessel connections to the liver. The only confusion was sometimes mixing up glycogen with glucagon. Several went well beyond the mark scheme (and sometimes the syllabus) with descriptions of hemoglobin breakdown, bile production and treatment of amino acids.