Lard is a solid fat at room temperature. What does this indicate about the structure of the triglycerides found in lard?

• A. They contain mostly unsaturated fatty acid chains.
• B. They have a high proportion of cis double bonds.
• C. They contain mostly saturated fatty acid chains.
• D. They are composed primarily of short-chain fatty acids.

Answer: (C)

Verified step by step guidance

1. Understand that the physical state of fats at room temperature is influenced by the types of fatty acid chains in their triglycerides.
2. Recall that saturated fatty acid chains have no double bonds, allowing them to pack closely together, which increases the melting point and makes the fat solid at room temperature.
3. Recognize that unsaturated fatty acids contain one or more double bonds, especially cis double bonds, which introduce kinks and prevent tight packing, resulting in a lower melting point and a liquid state at room temperature.
4. Note that short-chain fatty acids tend to have lower melting points, so fats rich in short-chain fatty acids are more likely to be liquid rather than solid at room temperature.
5. Conclude that since lard is solid at room temperature, its triglycerides must predominantly contain saturated fatty acid chains, allowing tight packing and a higher melting point.