DNA sequence is the basis of grouping organisms in

Options

A. Karyotaxonomy
B. Cytotaxonomy
C. Phenetics
D. Chemotaxonomy

Answer

To answer the question "DNA sequence is the basis of grouping organisms in," we need to analyze the options provided: Karyotaxonomy, Cytotaxonomy, Phenetics, and Chemotaxonomy. Let's go through each option step by step.

### Step-by-Step Solution:

1. **Understanding Karyotaxonomy**:
- Karyotaxonomy is the branch of systematics that focuses on the study of the structure of the cell nucleus and its components, particularly the chromosomes.
- It does not primarily utilize DNA sequences for grouping organisms but rather looks at the physical characteristics of chromosomes.
- **Conclusion**: Karyotaxonomy is not based on DNA sequences.

**Hint**: Karyotaxonomy relates to the structure of chromosomes, not DNA sequences.

2. **Understanding Cytotaxonomy**:
- Cytotaxonomy deals with the classification of organisms based on cytological information, such as chromosome number and structure.
- Similar to Karyotaxonomy, it does not focus on the DNA sequence but rather on observable cytological traits.
- **Conclusion**: Cytotaxonomy is also not based on DNA sequences.

**Hint**: Cytotaxonomy focuses on chromosome characteristics, not DNA sequences.

3. **Understanding Phenetics**:
- Phenetics is a classification system that groups organisms based on overall similarities, which can include morphological traits and other observable characteristics.
- This method does not specifically rely on DNA sequences but rather on physical traits.
- **Conclusion**: Phenetics does not use DNA sequences for grouping.

**Hint**: Phenetics groups organisms based on observable traits, not DNA sequences.

4. **Understanding Chemotaxonomy**:
- Chemotaxonomy involves the classification of organisms based on their chemical constituents, including biochemical compounds and DNA sequences.
- It utilizes the similarities and differences in biochemical constituents, which can include DNA sequences, making it relevant for grouping organisms.
- **Conclusion**: Chemotaxonomy is indeed based on DNA sequences.

**Hint**: Chemotaxonomy includes DNA sequences as part of its classification criteria.

### Final Answer:
The correct answer is **Chemotaxonomy**, as it uses DNA sequences as a basis for grouping organisms.