Nearly all infants benefit from milk, but most adults cannot properly digest milk. If an elderly person can still digest milk, his body is producing enough of which enzyme ?

The correct answer is (D) Lactase. Milk contains a disaccharide sugar called lactose. To digest it, the body must produce the enzyme lactase, which breaks lactose down into simpler sugars (glucose and galactose) that can be absorbed into the bloodstream.

• Lactase: While almost all infants produce high levels of lactase to digest breast milk, many adults experience a decline in its production, leading to lactose intolerance. An adult who can digest milk easily is still producing sufficient lactase.
• Cellulase: This enzyme breaks down cellulose found in plant cell walls; humans do not produce it.
• Amylase: This enzyme, found in saliva and the pancreas, is responsible for breaking down starches (complex carbohydrates) into sugars.
• Pectase: Also known as pectinase, it breaks down pectin found in plant cell walls and is not involved in milk digestion.