Which component of a chemical reaction does not change from beginning to end? A co-factor Substrate concentration Enzyme concentration Hot temperature

To determine which component of a chemical reaction does not change from beginning to end, we must analyze each option provided:

1. Cofactor: Cofactors are non-protein substances that assist enzymes in their activity. While they may bind to the enzyme, they do not change in quantity during the reaction; they are used in catalytic processes but do not become permanent parts of the reaction products.

2. Substrate concentration: The concentration of substrates typically decreases as they are converted into products during the chemical reaction.

3. Enzyme concentration: Enzymes are catalysts that remain unchanged in terms of their quantity throughout the reaction. Even though they may interact with substrates, they return to their original state after the reaction.

4. Hot temperature: Temperature can influence the rate of reaction, but it is not a "component" of the reaction in the same sense as substrates or enzymes. It can change throughout the reaction based on conditions.

Conclusion

The correct answer is Enzyme concentration. Enzymes do not change in amount from the beginning to the end of the reaction, although they participate actively in the process.