# Explain how the structure of a triglyceride makes it suitable for energy storage in animals.

> IB DP Biology Higher Level (2023 syllabus) — B1.1 Carbohydrates and lipids · Explain · 4 marks

## Mark scheme (4 marks)

1. Triglycerides are composed of one glycerol molecule bonded to three fatty acid chains via ester bonds, giving a high ratio of C–H bonds relative to molecular mass.
2. The long hydrocarbon chains of the fatty acids are highly reduced (rich in C–H bonds), so oxidation during respiration releases a large amount of energy per gram compared with carbohydrates.
3. Triglycerides are non-polar / hydrophobic and therefore do not associate with water molecules, so they are stored anhydrously, adding no osmotic load to cells.
4. Triglycerides are stored as compact, insoluble droplets in adipocytes, insulating the organism and acting as a metabolic water source when oxidised, making them well-suited for long-term energy reserves.

## Key terms

- [triglyceride](https://www.gradenine.co.uk/glossary/triglyceride)

## Related

- [Revision notes for IB DP Biology Higher Level (2023 syllabus)](https://www.gradenine.co.uk/learn)
- [How to answer "Explain" questions](https://www.gradenine.co.uk/tools/command-word-cheatsheet)
- [Practice this with AI marking (free)](https://www.gradenine.co.uk/start)

---
Source: [GradeNine](https://www.gradenine.co.uk/q/explain-how-the-structure-of-a-3ef7d86f) · Published by Druglandscape Ltd.