The vitamin that acts as a hormone in the body and is synthesized in the skin upon exposure to ultraviolet (UV) sunlight is: MCQ with Answer and Explanation

Explanation:
The appendix is considered vestigial (reduced and non-essential), but recent studies suggest it may have a minor immune function or serve as a reservoir for gut bacteria. So R is not entirely true (it may have a function). Thus, A is true but R is false (no function is an oversimplification).

Explanation:
Abscission is the natural shedding of plant parts. It is primarily promoted by ethylene and abscisic acid (ABA), which stimulate the formation of an abscission zone at the base of the petiole or pedicel. This zone consists of weak-walled cells that break down, causing the part to fall. Auxin, conversely, delays abscission. Exam tip: Ethylene is the 'ripening and shedding' hormone.

Explanation:
Somatostatin is a powerful, universal inhibitory peptide hormone. In the gastrointestinal tract and pancreas, it is secreted by the Delta (D) cells of the pancreatic islets and the D cells of the gastric and intestinal mucosa. Its primary role in the GI tract is to act as a paracrine inhibitor, suppressing the release of almost all other gastrointestinal hormones, including gastrin, secretin, cholecystokinin (CCK), vasoactive intestinal peptide (VIP), and gastric inhibitory peptide (GIP). It also inhibits gastric acid secretion, pancreatic enzyme secretion, and intestinal motility, acting as a 'brake' on the digestive system.