A group of researchers uses a bomb calorimeter to investigate the energy density of five different seed extracts (labeled P to T) with varying lipid contents.
Prior to placing the seed extracts inside the bomb calorimeter, each sample is thoroughly dehydrated to remove all water. Explain why this step improves the accuracy of the energy density determination.
Table 1 shows the lipid content of each seed extract in grams per 100 grams of dry mass. Table 2 shows the measured energy content in kilojoules per gram (kJ/g\text{kJ/g}kJ/g) across three experimental trials.
Table 1: Lipid content
| Seed Extract | Lipid content (g per 100g) |
|---|---|
| P | 8.5 |
| Q | 22.4 |
| R | 41.8 |
| S | 59.1 |
| T | 81.3 |
Table 2: Energy content (kJ/g\text{kJ/g}kJ/g)
| Seed Extract | Trial 1 | Trial 2 | Trial 3 | Calculated Mean |
|---|---|---|---|---|
| P | 3.8 | 4.2 | 4.0 | 4.0 |
| Q | 9.2 | 9.8 | 9.5 | 9.5 |
| R | 16.4 | 32.8 | 16.6 | 16.5 |
| S | 23.5 | 24.1 | 23.8 | 23.8 |
| T | 31.9 | 32.5 | 32.2 | 32.2 |
Identify the anomalous reading in Table 2, stating the seed extract and trial number. Explain how this anomaly should be treated when calculating the mean energy content.
Use the data to explain whether the results support the conclusion that seed extracts with higher lipid content have a greater energy content.
Name two other classes of large biological macromolecules in food, besides lipids, that contain energy.
