The two-kingdom classification of the living world was considered inadequate because :-

Options

A. It does not provide clear cut demarcation between prokaryotes and eukaryotes.
B. It includes fungi under plant kingdom though they are saprotrophic and store glycogen
C. In this classification position of euglenoid is not fixed.
D. All of the above

Answer

**Step-by-Step Solution:**

1. **Understanding the Two-Kingdom Classification**: The two-kingdom classification system divides all living organisms into two main categories: plants and animals. This system was proposed by Carl Linnaeus and was widely accepted for many years.

2. **Inadequacy of the Two-Kingdom System**: The two-kingdom classification was considered inadequate for several reasons:
- **Lack of Distinction Between Prokaryotes and Eukaryotes**: This classification did not differentiate between prokaryotic organisms (like bacteria) and eukaryotic organisms (like plants and animals). Prokaryotes lack a defined nucleus, while eukaryotes have a well-defined nucleus.

3. **Misclassification of Fungi**: Fungi were classified under the plant kingdom due to their stationary nature and the presence of a cell wall. However, fungi are fundamentally different from plants as they are heterotrophic (they obtain food by absorption) and have a different cell wall composition (chitin instead of cellulose).

4. **Position of Euglena**: The classification did not clearly define the position of euglena, a microorganism that exhibits both plant-like (photosynthesis) and animal-like (motility) characteristics. This ambiguity made it difficult to classify euglena accurately.

5. **Emergence of the Five-Kingdom Classification**: Due to these inadequacies, scientists like Robert Whittaker proposed a five-kingdom classification system that better categorized organisms based on their cellular organization, mode of nutrition, and other characteristics. This system includes Monera (prokaryotes), Protista, Fungi, Plantae, and Animalia.

6. **Conclusion**: The two-kingdom classification system was inadequate because it failed to provide a clear distinction between different types of organisms, leading to misclassification and confusion regarding the relationships among various life forms.

**Final Answer**: The two-kingdom classification of the living world was considered inadequate because it did not provide clear-cut demarcation between prokaryotes and eukaryotes, misclassified fungi under plants, and had an ambiguous position for euglena.

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