Question

Which of the following has 32 amino acids and a water-soluble peptide hormone?
A. Gastrin
B. Calcitonin
C. Glucagon
D. Insulin

Answer 1

Hint: Calcitonin is a hormone that is produced by the parafollicular cells (commonly known as C-cells) of the thyroid gland.

Complete answer: Gastrin: Gastrin is a peptide hormone that stimulates the secretion of gastric acid (HCl) by the parietal cells of the stomach and aids in gastric motility. It is released by G cells in the pyloric antrum of the stomach, duodenum, and the pancreas. Gastrin binds to cholecystokinin B receptors to stimulate the release of histamines.
Gastrin induces the insertion of $K^+$/$H^+$ ATPase pumps into the apical membrane of parietal cells (which in turn increases $H^+$ release into the stomach cavity).

Calcitonin: Calcitonin is involved in helping to regulate levels of calcium and phosphate in the blood, opposing the action of parathyroid hormone. It acts to reduce calcium levels in the blood. Calcitonin is a 32 amino acid peptide hormone secreted by parafollicular cells of the thyroid gland in humans and in many other animals. Calcitonin is water-soluble.

Glucagon: Glucagon is a peptide hormone, produced by alpha cells of the pancreas.
Glucagon is a hormone that raises the concentration of glucose and fatty acids in the bloodstream and is considered to be the main catabolic hormone of the body.

Insulin: Insulin is a peptide hormone produced by beta cells of the pancreatic islets.
It is considered to be the main anabolic hormone of the body.
It regulates the metabolism of carbohydrates, fats, and protein by promoting the absorption of glucose from the blood into the liver, fat, and skeletal muscle cells.
Insulin causes the liver to convert excess glucose into glycogen (this process is called glycogenesis). It forces blood to take up glucose from the blood through the GLUT4 transporter, thus decreasing blood sugar.

So, the answer is B. Calcitonin

Note: Studies depict that the deficiency of calcitonin may cause increased bone degradation and osteopenia.