Question

Which kingdom is included in all kingdom system classifications?

• A. Monera
• B. Protista
• C. Fungi
• D. Plantae and Animalia

Hint:

Always included: Plantae and Animalia — the foundation of every classification system, from two-kingdom to six-kingdom models.

Answer 1

The Correct Option is D

Throughout the history of biological classification, the categorization of organisms into kingdoms has evolved. Early systems began with just two kingdoms: Plantae and Animalia. Even as newer systems were proposed—such as the three-kingdom (including Protista), four-kingdom (adding Monera), five-kingdom (adding Fungi), and six-kingdom systems—Plantae and Animalia have always remained a constant part of every classification.
This is because plants and animals are the most distinct and universally recognized groups of multicellular organisms. Their inclusion dates back to Aristotle and Linnaeus and has persisted through all modern biological classification systems due to their fundamental biological differences in nutrition, mobility, and structure.
In contrast:

• Monera was not present in early two-kingdom systems.
• Protista emerged later as a catch-all for unicellular organisms.
• Fungi were initially grouped with plants and only later given a separate kingdom.

Therefore, only Plantae and Animalia have been included consistently in all kingdom classification systems.