Final answer:
The false statement about the duodenum is that it is longer than either the ileum or jejunum, as it is actually the shortest part of the small intestine.
Step-by-step explanation:
The statement about the duodenum that is false is that it is longer than either the ileum or jejunum. The duodenum is indeed the first and shortest part of the small intestine, where most chemical digestion takes place.
The duodenum does receive partially digested food mixed with acid, known as chyme, from the stomach. It is also where secretions from the liver and pancreas, including bile and digestive enzymes, act upon this mixture to facilitate digestion. The duodenum is less movable than the ileum or jejunum due to its position and the way it is anchored in the abdominal cavity. Therefore, the other three statements provided are true, and only the last one is false.