The variation of the rate of an enzyme catalysed reaction with substrate concentration is correctly represented by graph

Options

A.
B.
C.
D.

Answer

To solve the question regarding the variation of the rate of an enzyme-catalyzed reaction with substrate concentration, we can follow these steps:

### Step-by-Step Solution:

1. **Understanding Enzyme-Catalyzed Reactions**:
- Enzymes are biological catalysts that increase the rate of chemical reactions without being consumed in the process. The rate of an enzyme-catalyzed reaction typically depends on the concentration of the substrate.

2. **Analyzing the Relationship**:
- Initially, as the substrate concentration increases, the rate of the reaction also increases. This is because more substrate molecules are available for the enzyme to act upon.

3. **Identifying the Saturation Point**:
- However, there comes a point where all the active sites of the enzyme molecules are occupied. This is known as the saturation point. Beyond this point, adding more substrate does not increase the rate of reaction because the enzyme is already working at its maximum capacity.

4. **Graphical Representation**:
- The correct graph representing this relationship will show an initial increase in the rate of reaction with increasing substrate concentration, followed by a plateau where the rate remains constant despite further increases in substrate concentration.

5. **Choosing the Correct Option**:
- Among the given options, the graph that shows an initial rise followed by a plateau (constant rate) is the correct representation of the enzyme-catalyzed reaction with respect to substrate concentration. This corresponds to option 3.

### Conclusion:
The correct answer is option 3, which illustrates the characteristic curve of an enzyme-catalyzed reaction where the rate increases with substrate concentration up to a certain point and then levels off.