What was the basis of Whittaker's five kingdom system of classification of microorganisms

Options

A. External morphology
B. Energy yielding system
C. Cell anatomy
D. Both B and C

Answer

### Step-by-Step Solution:

1. **Understanding Whittaker's Classification**: Whittaker proposed a five-kingdom system of classification that includes Monera, Protista, Fungi, Plantae, and Animalia. This classification was developed to categorize living organisms based on certain criteria.

2. **Criteria for Classification**: The basis of Whittaker's five kingdom system primarily revolves around two main criteria:
- **Cell Structure Complexity**: This refers to whether the organism is unicellular or multicellular, and whether it has a cell wall or not.
- **Modes of Nutrition**: This includes how organisms obtain their food, which can be categorized into:
- **Autotrophic**: Organisms that produce their own food (e.g., plants).
- **Heterotrophic**: Organisms that obtain food from other sources. This can further be divided into:
- **Absorptive**: Organisms that absorb nutrients (e.g., fungi).
- **Ingestive**: Organisms that ingest food (e.g., animals).

3. **Analyzing the Options**:
- **Option A (External Morphology)**: This is incorrect as Whittaker did not focus on external morphological characteristics for his classification.
- **Option B (Energy Yielding System)**: This is correct as it relates to the nutritional modes of organisms.
- **Option C (Cell Anatomy)**: This is also correct as it pertains to the complexity of the cell structure.
- **Option D (Both B and C)**: Since both B and C are correct, this option is the most accurate.

4. **Conclusion**: The basis of Whittaker's five kingdom system of classification of microorganisms is primarily based on cell structure complexity and modes of nutrition, leading us to conclude that the correct answer is option D (Both B and C).