The cellular enzymes act as catalysts. The small size of cells keeps reactants together. The pH of the cytoplasm increases reaction rate. The reactants are present in small quantities in the cell.
I gave my students this multiple choice question: Biochemical reactions that require high temperatures to proceed are able to take place at body temperature within the cells of living organisms. Which factor is mainly responsible for allowing biochemical reactions to proceed at body temperature?

Only one answer is correct among these 4 choices:
- The cellular enzymes act as catalysts.
- The small size of cells keeps reactants together.
- The pH of the cytoplasm increases reaction rate.
- The reactants are present in small quantities in the cell.

Could you tell me which one is correct?

The cellular enzymes act as catalysts.