How did the classification of microorganisms change from the kingdom system to the domain system in taxonomy?

• A. The domain system eliminated the use of genetic information for classification.
• B. The domain system introduced three domains—Bacteria, Archaea, and Eukarya—based on differences in ribosomal RNA sequences.
• C. The domain system grouped all microorganisms into a single domain called Prokaryota.
• D. The domain system classified organisms solely based on their mode of nutrition.

Answer: (B)

Verified step by step guidance

1. Step 1: Understand the traditional kingdom system, which classified organisms into broad groups such as Monera, Protista, Fungi, Plantae, and Animalia, primarily based on observable characteristics like cell structure and nutrition.
2. Step 2: Recognize that advances in molecular biology, especially the analysis of genetic material like ribosomal RNA (rRNA) sequences, provided new insights into evolutionary relationships among organisms.
3. Step 3: Learn that the domain system was introduced to reflect these genetic differences more accurately, dividing life into three domains: Bacteria, Archaea, and Eukarya, which represent fundamental differences in cell types and genetic makeup.
4. Step 4: Note that this system emphasizes molecular data, particularly rRNA sequence comparisons, rather than just morphological or nutritional traits, allowing for a more precise classification of microorganisms.
5. Step 5: Conclude that the domain system replaced the kingdom system by focusing on genetic relationships, leading to a clearer understanding of microbial diversity and evolutionary history.