The mode of action of an enzyme is:

Options

A. Decreasing potential energy
B. Increasing activation energy
C. Increasing kinetic energy
D. Decreasing activation energy

Answer

To solve the question regarding the mode of action of an enzyme, we can break it down into the following steps:

### Step 1: Understand the Role of Enzymes
Enzymes are biological catalysts that speed up chemical reactions in the body. They do this by lowering the activation energy required for the reaction to occur.

**Hint:** Enzymes are crucial for facilitating biochemical reactions by reducing the energy barrier.

### Step 2: Analyze the Graph
In the provided graph, we have two lines representing reactions: one without an enzyme (blue line) and one with an enzyme (dotted line). The x-axis represents the reaction progress, while the y-axis represents energy.

**Hint:** Pay attention to how the activation energy changes when an enzyme is involved in the reaction.

### Step 3: Compare Activation Energies
From the graph, we observe that:
- The activation energy (Ea) for the reaction without an enzyme is high.
- The activation energy for the reaction with the enzyme is significantly lower.

**Hint:** Look for the difference in energy levels between the two scenarios to understand the enzyme's effect.

### Step 4: Conclude the Mode of Action
Since the enzyme lowers the activation energy required for the reaction, it allows the reaction to proceed more easily and quickly. This means that the correct answer to the question is that the mode of action of an enzyme is to decrease activation energy.

**Hint:** Remember that the primary function of enzymes in biochemical reactions is to make them more efficient by lowering energy requirements.

### Final Answer
The mode of action of an enzyme is to **decrease activation energy**.