Which of the following is not a secondary metabolite of plant cell ?

Options

A. Rubber
B. Chlorophyll
C. Essential oil
D. Tannins

Answer

To determine which of the following is not a secondary metabolite of plant cells, we need to first understand the definitions of primary and secondary metabolites.

### Step-by-Step Solution:

1. **Define Metabolites**: Metabolites are the intermediates or end products of metabolism in living organisms. They can be classified into two main categories: primary metabolites and secondary metabolites.

2. **Identify Primary Metabolites**: Primary metabolites are substances that have identifiable functions and play known roles in normal physiological processes. Examples include carbohydrates, proteins, lipids, and chlorophyll.

3. **Identify Secondary Metabolites**: Secondary metabolites, on the other hand, are those that do not have identifiable functions and do not play known roles in normal physiological processes. Examples include alkaloids, essential oils, and tannins.

4. **Analyze the Options**:
- **Rubber**: This is a secondary metabolite produced by plants.
- **Chlorophyll**: This is a primary metabolite, as it plays a crucial role in photosynthesis by absorbing light energy.
- **Essential Oils**: These are secondary metabolites, often used for their aromatic properties.
- **Tannins**: These are also secondary metabolites, known for their role in plant defense.

5. **Conclusion**: Since chlorophyll is the only option that is a primary metabolite, it is the correct answer to the question of which is not a secondary metabolite of plant cells.

### Final Answer: **Chlorophyll**

---