Carbohydrates and Lipids · Paper 2 — Free Biology SL Practice Questions

A student investigates the effect of temperature on the rate of starch digestion by amylase. She adds amylase to a starch solution at $37\,°\text{C}$ and at $60\,°\text{C}$, then measures the concentration of maltose produced every 2 minutes for 10 minutes. Her results are shown below. Time (min) — Maltose at $37\,°\text{C}$ ($\text{g\,L}^{-1}$) — Maltose at $60\,°\text{C}$ ($\text{g\,L}^{-1}$) 0.0 — 0.0 2 — 1.2 — 0.3 4 — 2.4 — 0.6 6 — 3.6 — 0.9 8 — 4.8 — 1.2 10 — 6.0 — 1.5

A biology student sets up an experiment using dialysis tubing to model the digestion of starch. She fills one bag with a $2\%$ starch solution and a second bag with a $2\%$ starch solution mixed with amylase. Both bags are placed in separate beakers of distilled water at $37\,^\circ\text{C}$. After 30 minutes, she tests the water outside each bag for the presence of starch (using iodine solution) and for reducing sugars (using Benedict's reagent). Results: - Bag 1 (starch only): iodine test — water remains yellow-brown; Benedict's test — water remains blue. - Bag 2 (starch + amylase): iodine test — water remains yellow-brown; Benedict's test — water turns orange-red.

A study investigated the effect of acarbose, an amylase inhibitor, on starch digestion in humans. Eight healthy volunteers each consumed a standard meal containing $50\,\text{g}$ of starch. Blood glucose concentration was measured at 30-minute intervals for 180 minutes after the meal. The experiment was repeated one week later with the same volunteers; each volunteer took $100\,\text{mg}$ of acarbose immediately before the meal. Time after meal $(\text{min})$ — Mean blood glucose without acarbose $(\text{mmol}\,\text{L}^{-1})$ — Mean blood glucose with acarbose $(\text{mmol}\,\text{L}^{-1})$ 0 — 4.8 30 — 7.2 — 6.1 60 — 8.5 — 6.8 90 — 7.9 — 6.4 120 — 6.5 — 5.7 150 — 5.6 — 5.2 180 — 5.0 — 4.9