Final answer:
Folate, a B vitamin, is not digested but directly absorbed from the small intestine into the bloodstream. Its absorption can be inhibited by factors such as alcohol and certain medications. Unlike folate, proteins are digested beginning in the stomach with pepsin and further processed in the small intestine.
Step-by-step explanation:
Folate, a type of B vitamin, is not subject to digestion in the gastrointestinal tract. Therefore, the correct answer to your question would be (c) Folate is not subject to digestion in the gastrointestinal tract. Instead, it is directly absorbed into the bloodstream primarily from the small intestine. It's also worth noting that certain factors can inhibit the absorption of folate, such as alcohol, certain medications, and malabsorptive disorders.
For comparison, the digestion of proteins begins in the stomach, facilitated by an enzyme called pepsin in a highly acidic environment. Pepsin is secreted by the chief cells in the stomach in an inactive form called pepsinogen, which is activated in the presence of gastric hydrochloric acid secreted by parietal cells. This acidic environment also kills many microorganisms in the food and, combined with the action of pepsin, results in the catabolism of protein in the food. Chemical digestion is further facilitated by the churning action of the stomach, and the result of this partial digestion is a substance called chyme.
Only a small amount of chyme is released into the small intestine at a time, which is where further protein digestion takes place. The movement of chyme from the stomach into the small intestine is regulated by hormones, stomach distension and the pyloric sphincter. Proteolytic enzymes are absent in salivary secretions, hence no digestion of proteins in the mouth. The digestion and subsequent absorption of proteins are an essential part of overall human nutrition, along with the absorption of vitamins like folate and other nutrients.
Learn more about Digestion of Folate and Proteins