Phenetic classification of organisms is based on

Options

A. The ancestral lineage of existing organisms
B. Observable characteristics of existing organisms
C. Dendrograms based on DNA characteristics
D. Sexual characteristics

Answer

**Step-by-Step Solution:**

1. **Understanding Phenetic Classification:**
- Phenetic classification is a method of classifying organisms based on observable traits rather than their evolutionary relationships. The term "phenetic" comes from the Greek word "phenane," which means "to appear."

2. **Identifying the Basis of Classification:**
- This classification system focuses on morphological similarities and differences among organisms. Morphological traits are those that can be observed, such as shape, size, and structure.

3. **Evaluating the Options:**
- **Option A: Ancestral lineage of existing organisms** - This option refers to evolutionary relationships, which are not considered in phenetic classification. Therefore, this option is incorrect.
- **Option B: Observable characteristics of existing organisms** - This option aligns with the definition of phenetic classification, as it is based on traits that can be seen. This is the correct option.
- **Option C: Dendrograms on DNA characteristics** - Dendrograms are used to represent genetic relationships, which are not part of phenetic classification. Thus, this option is incorrect.
- **Option D: Sexual characteristics** - This option focuses on reproductive traits, which are not relevant to phenetic classification. Therefore, this option is also incorrect.

4. **Conclusion:**
- The correct answer is **observable characteristics of existing organisms**, as phenetic classification relies solely on visible traits rather than genetic or evolutionary factors.