How many kingdoms are there in the domain Eukarya? A. 3 B. 2 C. 4 D. 1
The correct answer and explanation is:
Correct Answer: C. 4
The domain Eukarya consists of organisms that have eukaryotic cells, which are cells with a true nucleus and membrane-bound organelles. Within this domain, there are traditionally four recognized kingdoms: Protista, Fungi, Plantae, and Animalia.
- Protista includes mostly unicellular organisms, although some multicellular forms exist. These organisms do not fit neatly into the other three kingdoms. Examples include amoebas and algae. Protists can be autotrophic or heterotrophic and exhibit a wide range of lifestyles.
- Fungi includes multicellular molds and mushrooms, as well as unicellular yeasts. These organisms are heterotrophic, meaning they absorb nutrients from external sources. Fungi have cell walls made of chitin and reproduce through spores.
- Plantae includes multicellular, photosynthetic organisms such as mosses, ferns, and flowering plants. These organisms have cell walls made of cellulose and contain chloroplasts that perform photosynthesis. They are autotrophic and form the base of many food chains.
- Animalia includes multicellular, heterotrophic organisms that lack cell walls and are usually motile at some stage of life. Animals range from simple sponges to complex mammals.
Although some modern classification systems based on molecular data propose revisions, the traditional model recognizes these four kingdoms in the domain Eukarya. Some biologists advocate for breaking up Protista into multiple kingdoms because of its diverse nature, but the four-kingdom classification remains widely taught and understood.
The concept of domains and kingdoms helps organize biological diversity by grouping organisms with shared characteristics. The domain Eukarya distinguishes itself from the other two domains, Archaea and Bacteria, by its more complex cell structure.