Question

an enzyme is: a a type of molecule found in the stomach to break down starch b a type of protein that is able to catalyze reactions c a type of nucleic acid that helps with dna replication and storage d a type of carbohydrate that is indigestible for the human stomach

Explanation:

• Option A: Starch breakdown mainly occurs in the mouth (via salivary amylase) and small intestine, not the stomach, so A is incorrect.
• Option B: Enzymes are mostly proteins (some are RNA, but the primary type is protein) that act as biological catalysts to speed up reactions, so B is correct.
• Option C: Nucleic acids (DNA, RNA) are for genetic info, not enzyme function (enzymes catalyze, not handle DNA replication/storage in this way), so C is incorrect.
• Option D: Enzymes are not carbohydrates; indigestible carbohydrates like fiber are different, so D is incorrect.

Answer:

B. a type of protein that is able to catalyze reactions