NANP Board Practice Exam

Which of the following is not a factor affecting the rate of starch digestion?

1. Cell wall or protein encapsulation

2. Composition of starch complexes

3. Food particle size

4. Presence of lactase

The correct answer is: Presence of lactase

The presence of lactase does not influence the rate of starch digestion because lactase is an enzyme specifically responsible for the digestion of lactose, the sugar found in milk and dairy products. It breaks down lactose into glucose and galactose, which are absorbed into the bloodstream. In contrast, the other listed factors directly affect starch digestion. The cell wall or protein encapsulation can hinder the accessibility of starch to enzymes, thus impeding digestion. The composition of starch complexes can influence how easily enzymes can break them down, affecting digestion rates. Additionally, food particle size impacts the surface area available for enzyme action; smaller particles provide more area for enzymes to act upon, enhancing the digestion process. Therefore, while lactase is vital for breaking down lactose, it does not play a role in starch digestion, making it the correct choice for this question.