IB Biology option d3 liver

1. OPTION D
D.3 FUNCTIONS OF THE LIVER

7. • Regulation of blood glucose level.
• Regulation of lipids.
• Low density lipoproteins are formed by liver
cells.
• Surplus cholesterol is converted into bile salts.

8. • Glucose is stored as glycogen.
• Iron, retinol (Vitamin A) and calciferol (Vitamin
D) are stored in the liver.

9. • The typical lifespan of a RBC is 120 days.
• Old RBC are taken by macrophages.
• They are removed from the blood circulation
and are broken down in the spleen and the
liver.

29. Answers
• 1. a) as the rate of bile salt secretion goes up, the rate of
flow of bile increases;
• b) bile salts draw water into the narrow canaliculi (by
osmosis) and this increase the flow rate;
• 2. after the consumption of a meal containing fat;
• 3. secretin causes an increase in the rate of bile flow; at all
rates of bile salt release/increase caused is uniform; 4 when
concentration of bile salt is zero, there is still flow of bile,
indicating something else was drawing water into the tubes;

31. Answers
1. (i) as percent triglycerides increases, density goes
down;
(ii) as percent protein increases, density increases;
(iii) as percent cholesterol increases, density
increases;
2. the % cholesterol is very similar in both;
3. because LDL contain higher levels of cholesterol
which can contribute to plaque formation;