The criteria for classification are changing over time. Why?

Answer

### Step-by-Step Text Solution:

1. **Understanding Classification**: Classification of organisms involves grouping them based on shared characteristics. Initially, organisms were classified based on their utility or practical uses to humans.

2. **Historical Context**: In earlier times, organisms were categorized based on their applications. For instance, types of timber were classified according to their use in construction, while spices were classified based on their flavor and culinary uses.

3. **Advancements in Science**: As scientific knowledge progressed, particularly with advancements in microscopy and cellular biology, our understanding of organisms deepened. This led to new criteria for classification.

4. **Cellular Characteristics**: The discovery of cellular structures, such as the presence or absence of a nucleus, became a significant factor in classification. Organisms were divided into two main groups:
- **Prokaryotes**: Organisms with no well-defined nucleus.
- **Eukaryotes**: Organisms with a well-defined nucleus.

5. **Modes of Nutrition**: Further advancements revealed different modes of nutrition among organisms (e.g., autotrophic vs. heterotrophic). This understanding contributed to refining classification criteria.

6. **Ongoing Changes**: The criteria for classification continue to evolve as new discoveries are made in genetics, molecular biology, and ecology. Improved understanding of evolutionary relationships and genetic similarities has led to more accurate classifications.

7. **Conclusion**: The criteria for classification are changing over time due to advancements in scientific knowledge, improved understanding of biological characteristics, and the discovery of new information about organisms.