Biological catalysts are protein molecules which 1. speed up a chemical reaction 2. remain unchanged after reaction 3. function optimally at 37 °C 4. do not have an enzymatic activity Select the correct answer using the code given below.

Biological catalysts, primarily known as enzymes, are protein molecules that significantly speed up chemical reactions by lowering activation energy. As catalysts, they are not consumed or permanently altered during the reaction, allowing them to be reused repeatedly [1]. Statement 3 is correct in the context of human biology, as most human enzymes function optimally at a body temperature of 37 °C. Deviations from this temperature can lead to denaturation, where the enzyme loses its structural integrity and function [1]. Statement 4 is incorrect because the defining characteristic of these molecules is their enzymatic (catalytic) activity [1]. While some RNA molecules (ribozymes) also act as catalysts, the question specifically identifies these biological catalysts as protein molecules, which aligns with the classical definition of enzymes [1].

Sources

1. [1] https://pmc.ncbi.nlm.nih.gov/articles/PMC4692135/