Which of the following types of molecules do cells primarily use for long-term energy storage?

• A. Amino acids
• B. Phospholipids
• C. Triglycerides
• D. Monosaccharides

Answer: (C)

Verified step by step guidance

1. Understand the role of each molecule type in cellular functions: Amino acids are primarily used for building proteins, phospholipids are key components of cell membranes, monosaccharides are used for short-term energy storage, and triglycerides are used for long-term energy storage.
2. Recall that long-term energy storage molecules must be efficient at storing large amounts of energy in a compact form. Triglycerides, composed of glycerol and three fatty acid chains, are ideal for this purpose due to their high energy density.
3. Recognize that monosaccharides, such as glucose, are used for immediate energy needs and are stored as glycogen for short-term energy, but they are not suitable for long-term storage due to their lower energy density compared to triglycerides.
4. Phospholipids, while important for forming cellular membranes, are not primarily used for energy storage. Their structure is optimized for creating bilayers rather than storing energy.
5. Conclude that triglycerides are the correct answer because they are specifically designed for long-term energy storage in cells, stored in adipose tissue and broken down during periods of energy demand.