An unsaturated fatty acid differs from a saturated one in that it

  • A. contains one or more carbon to carbon double bonds in its hydrocarbon chain
  • B. contains more hydrogen atoms per carbon
  • C. has no carboxyl group
  • D. cannot be used in respiration

Explanation

Each double bond puts a kink in the chain, so the molecules pack together less closely and the fat has a lower melting point, which is why plant oils are liquid while animal fats are solid at room temperature. Saturated means the chain carries the maximum possible hydrogen, so the unsaturated form has fewer hydrogens, not more. Diets high in saturated fat are linked with atherosclerosis.

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