Which of the following is not an enzyme?

The correct answer is A. Oxytocin.

Oxytocin is a hormone, not an enzyme. It is produced in the hypothalamus and released by the posterior pituitary gland. Oxytocin is involved in childbirth, breastfeeding, and social bonding.

Trypsin, pepsin, and ptyalin are all enzymes. Trypsin is a digestive enzyme that breaks down proteins. Pepsin is a digestive enzyme that breaks down proteins in the stomach. Ptyalin is a digestive enzyme that breaks down starch in the mouth.

Here is a more detailed explanation of each option:

• Oxytocin is a hormone that is produced in the hypothalamus and released by the posterior pituitary gland. It is involved in childbirth, breastfeeding, and social bonding. Oxytocin is not an enzyme.
• Trypsin is a digestive enzyme that breaks down proteins. It is produced in the pancreas and secreted into the small intestine. Trypsin is an exopeptidase, which means that it cleaves amino acids from the ends of proteins.
• Pepsin is a digestive enzyme that breaks down proteins in the stomach. It is produced by the chief cells of the stomach lining. Pepsin is an endopeptidase, which means that it cleaves amino acids from the middle of proteins.
• Ptyalin is a digestive enzyme that breaks down starch in the mouth. It is produced by the salivary glands. Ptyalin is an alpha-amylase, which means that it cleaves alpha-1,4-glycosidic bonds in starch.