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

Glycogen and starch are both polysaccharides used for glucose storage, but they differ in structure and occur in different organisms. A student investigates the rate of glucose release from glycogen and starch by the enzyme amylase. The student incubates $1.0\,\text{g}$ of each polysaccharide with $1.0\,\text{cm}^3$ of amylase solution at $37°\text{C}$ and $\text{pH}\;7.0$. The mass of glucose released is measured every 2 minutes for 10 minutes. Time / min — 0 — 2 — 4 — 6 — 8 — 10 Glucose from glycogen / mg — 0 — 12 — 22 — 30 — 36 — 40 Glucose from starch / mg — 0 — 8 — 15 — 21 — 26 — 30

Triglycerides are a type of lipid composed of glycerol and three fatty acid chains. A researcher compares the energy content of two triglycerides: one from butter (saturated) and one from olive oil (unsaturated). The researcher burns $0.5\,\text{g}$ of each triglyceride separately in a calorimeter containing $100\,\text{g}$ of water and records the temperature increase. Triglyceride — Temperature increase of water Butter (saturated) — $8.2\,°\text{C}$ Olive oil (unsaturated) — $7.6\,°\text{C}$ Specific heat capacity of water: $c = 4.18\,\text{J}\,\text{g}^{-1}\,°\text{C}^{-1}$ Use $Q = mc\Delta T$ where relevant.