中国大学MOOC: Phospholipids with short or unsaturated fatty acyl chains

Why do aldehydes undergo nucleophilic addition reactions while esters undergo nucleophilic acyl substitution reactions? A: The carbonyl carbon of an ester is more electrophilic than that of an aldehyde. B: Aldehydes are more sterically hindered than esters. C: Once the nucleophile adds to an aldehyde, the tetrahedral intermediate is too sterically hindered to eliminate one of the attached groups. D: Once the nucleophile adds to an aldehyde, neither H− nor R− can be eliminated since they are strongly basic.

Some athletes believe that dietary carnitine supplements will enhance their ability to perform aerobic exercise. Which statement BEST describes the “scientific” basis of this belief? A: Carnitine is required in the transport of medium and long-chain fatty acids into the mitochondrial matrix, and so increasing the amount of carnitine will increase the rate of transport. B: Carnitine activates carnitine-acyl transferase-1 (CAT-I) thereby increasing the rate of transport of fatty acids into the mitochondrial matrix. C: Carnitine levels in the cytoplasm are reduced when large amounts of fatty acyl carnitine are transported into the mitochondrial matrix. D: Carnitine enhances the activation of fatty acids to fatty acyl-CoA, thereby increasing the rate of their transport into the mitochondrial matrix.