Answer: An inactive enzyme precursor.
- A An active enzyme ready to catalyze reactions
- B An inactive enzyme precursor
- C A type of coenzyme assisting enzyme function
- D A regulatory protein controlling gene expression
Correct answer: B. An inactive enzyme precursor
Explanation: Zymogens (proenzymes) are inactive enzyme precursors activated by cleavage of a peptide. Example: pepsinogen is converted to pepsin by HCl in the stomach.
As substrate concentration rises, reaction rate increases steeply at first, then plateaus at Vmax once every enzyme molecule is working at full capacity; Km is the substrate concentration giving half-maximal rate, and a LOWER Km means the enzyme reaches that rate with less substrate (higher affinity).
Concept context
Carbohydrates, proteins, lipids, nucleic acids, and enzyme kinetics. Essential foundation for understanding metabolism.