Final answer:
The enzyme that acts on lactose to digest it into glucose and galactose is option a) lactase. This enzyme is crucial for lactose digestion in milk, and its deficiency can lead to lactose intolerance in adults.
Step-by-step explanation:
The enzyme that acts on lactose is option a)lactase.
Lactase is responsible for hydrolyzing lactose, a disaccharide found in milk, into its component monosaccharides - glucose and galactose. This process is vital for the proper digestion of milk sugars. In particular, the enzyme ß-galactosidase, encoded by the lacZ gene in bacteria such as E. coli, is known to perform a similar function. Additionally, lactose is a reducing sugar because it has a glucose unit with a free hemiacetal group which can exist in various forms in solution. Lactose is present in significant amounts in milk, and without lactase, many adults can develop lactose intolerance, leading to digestion issues when consuming dairy products.