A secondary metabolite that acts as a toxin is

Options

A. Carotenoids
B. Curcumin
C. Abrin
D. Monoterpenes

Answer

To answer the question "A secondary metabolite that acts as a toxin is:", we need to analyze the options provided: carotenoids, curcumin, abrin, and monoterpenes.

### Step-by-Step Solution:

1. **Understanding Secondary Metabolites**:
- Secondary metabolites are organic compounds that are not directly involved in the normal growth, development, or reproduction of an organism. They often play a role in defense mechanisms against predators, pathogens, or competition.

2. **Evaluating the Options**:
- **Carotenoids**: These are pigments found in plants that provide bright colors (yellow, red, orange) and have antioxidant properties. They are not known to be toxic.
- **Curcumin**: This is a compound found in turmeric (Curcuma longa) and is known for its medicinal properties. It is not toxic.
- **Abrin**: This is a toxic protein derived from the seeds of the rosary pea plant. It is indeed a secondary metabolite and is known for its poisonous effects.
- **Monoterpenes**: These are compounds found in essential oils that contribute to the aroma and flavor of plants. They are generally not toxic.

3. **Identifying the Correct Answer**:
- Among the options, abrin is the only secondary metabolite that acts as a toxin. Therefore, the correct answer is **abrin**.

### Final Answer:
The secondary metabolite that acts as a toxin is **abrin**.

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