Which of the following secondary metabolites is a polymeric substance ?

Options

A. Ricin
B. Monoterpenes
C. Curcumin
D. Rubber

Answer

To determine which of the following secondary metabolites is a polymeric substance, we need to analyze each option provided: resin, monoterpene, curcumin, and rubber.

### Step-by-Step Solution:

1. **Understand Secondary Metabolites**:
- Secondary metabolites are compounds produced by plants that are not directly involved in the growth, development, or reproduction of the organism. They often play roles in defense, competition, and attraction of pollinators.

2. **Analyze Each Option**:
- **Resin**: This is a sticky substance produced by plants, often used for protection against herbivores and pathogens. It is not a polymeric substance but rather a mixture of various compounds.

- **Monoterpene**: These are small, volatile compounds made up of two isoprene units. They are not polymers; instead, they are simple organic molecules.

- **Curcumin**: This is a secondary metabolite found in turmeric (Curcuma longa). It is a small molecule and not a polymer.

- **Rubber**: This is a polymeric substance, specifically an elastomer, which is made up of long chains of isoprene units (polyisoprene). It exhibits elastic properties, allowing it to stretch and return to its original shape.

3. **Conclusion**:
- Among the options given, rubber is the only secondary metabolite that is a polymeric substance.

### Final Answer:
The secondary metabolite that is a polymeric substance is **rubber**.

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