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 classification system was proposed by R.H. Whittaker in 1969. It categorizes living organisms into five distinct kingdoms: Monera, Protista, Fungi, Plantae, and Animalia.

2. **Criteria for Classification**: The classification is based on several criteria, including:
- **Cell Structure**: Whether the organism is prokaryotic (lacking a nucleus) or eukaryotic (having a nucleus).
- **Thallus Organization**: The complexity of the organism’s body structure.
- **Mode of Nutrition**: How the organism obtains its food (autotrophic vs. heterotrophic).
- **Reproduction**: The methods through which organisms reproduce (asexual vs. sexual).
- **Phylogenetic Relationship**: The evolutionary relationships among different organisms.

3. **Identifying the Main Basis**: Among all these criteria, the main basis of classification in the five kingdom system is the **mode of nutrition**. This is because it helps to distinguish between different groups of organisms based on how they obtain energy and nutrients.

4. **Conclusion**: Therefore, the correct answer to the question is that in the five kingdom system, the main basis of classification is the **mode of nutrition**.