An enzyme brings about

Options

A. decrease in reaction time
B. increase in reaction time
C. increase in activation energy
D. reduction in activation energy

Explanation

### Step-by-Step Solution:

1. **Understanding Enzymes**: Enzymes are biological catalysts that facilitate metabolic reactions in living organisms. They speed up reactions by lowering the activation energy required for the reaction to occur.

2. **Activation Energy**: Activation energy is the minimum amount of energy needed for a chemical reaction to occur. Without enzymes, this energy requirement is often too high for reactions to proceed efficiently in biological systems.

3. **Role of Enzymes**: Enzymes lower the activation energy barrier, making it easier for reactants (substrates) to convert into products. This is crucial for metabolic processes, as it allows reactions to occur at a rate that supports life.

4. **Example of Enzyme Action**: For instance, the enzyme sucrase catalyzes the hydrolysis of sucrose into glucose and fructose. Without sucrase, the reaction would require 32,000 calories per mole of energy, but with sucrase, it only requires 900 calories per mole. This significant reduction in energy requirement illustrates the enzyme's role in facilitating the reaction.

5. **Conclusion**: Therefore, the correct statement regarding the role of an enzyme is that it brings about a reduction in the activation energy required for a reaction to occur.

### Final Answer:
The enzyme brings about a reduction in the activation energy required for a reaction to occur.

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