The classification of plants and animals on the basis of chromosome number is called

Options

A. Cytotaxonomy
B. Biochemical systematics
C. Taxonomy
D. Numerical taxonomy

Answer

### Step-by-Step Solution:

1. **Understanding the Question**: The question asks for the classification of plants and animals based on their chromosome number.

2. **Identifying the Options**: The options provided are:
- Cytotaxonomy
- Biochemical systematics
- Taxonomy
- Numerical taxonomy

3. **Analyzing Each Option**:
- **Cytotaxonomy**: This is a branch of taxonomy that focuses on the cellular structure and content, including the chromosomal configuration of organisms. It specifically deals with the classification based on chromosome number.
- **Biochemical Systematics**: This field involves the study of biochemical characteristics and does not focus on chromosome numbers.
- **Taxonomy**: This is the general classification of organisms but does not specifically address chromosome numbers.
- **Numerical Taxonomy**: This method uses numerical data to classify organisms based on various characteristics, but it does not specifically classify based on chromosome numbers.

4. **Conclusion**: Since cytotaxonomy is the only option that specifically deals with the classification of plants and animals based on chromosome number, it is the correct answer.

### Final Answer:
The classification of plants and animals on the basis of chromosome number is called **Cytotaxonomy**.