In five kingdom system the main basis of classification is

Options

A. structure of nucleus
B. mode of nutrition
C. structure of cell wall
D. asexual reproduction

Answer

### Step-by-Step Solution:

1. **Understanding the Five Kingdom System**: The five kingdom system of classification was proposed by Robert Whittaker and includes Monera, Protista, Fungi, Plantae, and Animalia. Each kingdom is classified based on certain characteristics.

2. **Identifying the Options**: The options given in the question are:
- Structure of nucleus
- Mode of nutrition
- Structure of cell wall
- Asexual reproduction

3. **Analyzing Each Option**:
- **Structure of Nucleus**: This refers to whether a nuclear membrane is present or absent, which helps differentiate between prokaryotes (no nucleus) and eukaryotes (with nucleus).
- **Mode of Nutrition**: This indicates how organisms obtain their food, which can be autotrophic (self-feeding) or heterotrophic (feeding on others). This is a significant characteristic used in the classification.
- **Structure of Cell Wall**: This involves the composition of the cell wall, such as cellulose in plants and chitin in fungi, which is also important for classification.
- **Asexual Reproduction**: This refers to the methods of reproduction, such as binary fission or fragmentation.

4. **Determining the Main Basis of Classification**: While all these factors contribute to the classification, the primary basis in the five kingdom system is the **mode of nutrition**. This is because it directly relates to how organisms interact with their environment and obtain energy.

5. **Conclusion**: Therefore, the main basis of classification in the five kingdom system is the **mode of nutrition**.

### Final Answer:
The main basis of classification in the five kingdom system is the **mode of nutrition**.

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