Substances produced by plants as defence against grazers and browsers include

Options

A. Caffeine
B. Quinine
C. Nicotine
D. All of these

Answer

**Step-by-Step Solution:**

1. **Understanding the Question**: The question asks about substances produced by plants as a defense mechanism against grazers and browsers. Grazers and browsers are animals that feed on plants, and plants have evolved various strategies to protect themselves.

2. **Identifying the Substances**: The options provided in the question include caffeine, quinine, nicotine, and potentially others. We need to determine if these substances are indeed produced by plants for defense.

3. **Researching Each Substance**:
- **Caffeine**: This is a chemical compound found in coffee beans, tea leaves, and cacao pods. It acts as a natural pesticide and can deter herbivores due to its toxicity in high doses.
- **Quinine**: Extracted from the bark of the cinchona tree, quinine has been used historically for its medicinal properties and also serves as a deterrent against herbivores.
- **Nicotine**: Found in tobacco plants, nicotine is a potent neurotoxin to many herbivores, providing a strong defense against plant-eating animals.

4. **Conclusion**: All three substances—caffeine, quinine, and nicotine—are produced by plants as a defense mechanism against grazers and browsers. Therefore, the correct answer is that all of these options are correct.

5. **Final Answer**: Substances produced by plants as defense against grazers and browsers include caffeine, quinine, nicotine, and others.

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