Phenetic classification of organisms is based on

Options

A. dendograms based on DNA character- istics
B. sexual characteristics
C. the ancestral lineage of existing organisms
D. observable characteristics of existing organisms

Answer

### Step-by-Step Solution:

1. **Understanding Phenetic Classification**:
- Phenetic classification is a system used to categorize organisms based on observable traits and characteristics.

2. **Observable Characteristics**:
- This classification relies on physical features such as morphology (shape and structure), behavior, and other measurable traits of the organisms.

3. **Lack of Genetic Consideration**:
- Unlike other classification systems, phenetic classification does not take into account the genetic relationships or evolutionary history of the organisms.

4. **Example for Clarity**:
- Consider the example of a whale, dolphin, and rohu (a type of fish). All three are aquatic and have fin-like structures, which might suggest they belong to the same group in a phenetic classification.

5. **Misleading Grouping**:
- However, whales and dolphins are mammals, while the rohu is a fish. This illustrates a key limitation of phenetic classification: it can group organisms that are not closely related evolutionarily based solely on superficial similarities.

6. **Conclusion**:
- Therefore, the phenetic classification of organisms is based on the observable characteristics of existing organisms, but it may not accurately reflect their genetic or evolutionary relationships.

### Final Answer:
Phenetic classification of organisms is based on the observable characteristics of existing organisms.

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